KR100570760B1 - Light emitting display apparatus and display panel thereof - Google Patents

Abstract

The present invention relates to a light emitting display device and a display panel thereof. The light emitting display device according to the present invention includes a plurality of data lines for transmitting an analog data signal, a plurality of scan lines for crossing the data lines and transmitting a selection signal, and a plurality of images for displaying an image corresponding to the data signal in response to the selection signal. A pixel circuit, a data driver for applying a data signal corresponding to an input digital image signal to a plurality of data lines, and first and second power supply terminals for supplying a reference voltage to the data driver, wherein the data driver includes: A power supply line connected to the first and second power supply terminals, and a plurality of DA converters connected between the power supply line and the data line and converting an image signal into a data signal and applying the data signal to the data line.

Organic EL, Data Driver, DAC, Power Supply Line, Voltage Drop

Description

LIGHT EMITTING DISPLAY APPARATUS AND DISPLAY PANEL THEREOF}

1 shows a conventional organic EL display device.

2 illustrates a light emitting display device according to a first embodiment of the present invention.

3 illustrates the DA converter illustrated in FIG. 2 in more detail.

4 is a circuit diagram illustrating a sub DA converter according to an embodiment of the present invention.

FIG. 5 is a circuit diagram illustrating the sub-DA converter of FIG. 4 in more detail.

6 illustrates a light emitting display device according to a second embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to an organic electroluminescent (EL) display device and a display panel thereof.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by voltage driving or current driving N X M organic light emitting cells. The organic light emitting cell has a structure of an anode (ITO), an organic thin film, and a cathode layer (metal). The organic thin film has a multilayer structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) to improve the light emission efficiency by improving the balance between electrons and holes. It also includes a separate electron injecting layer (EIL) and a hole injecting layer (HIL).

The organic light emitting cell may be driven by a simple matrix method and an active matrix method using a thin film transistor (TFT) or a MOSFET. In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active driving method connects the thin film transistor and the capacitor to each indium tin oxide (ITO) pixel electrode to maintain the voltage by the capacitor capacitance. It is a driving method. In this case, the active driving method is divided into a voltage programming method and a current programming method according to the type of signal applied to maintain the voltage on the capacitor.

1 shows a conventional organic EL display device.

As shown in FIG. 1, the organic EL display device is composed of a display panel 10, a scan driver 20, and a data driver 30.

The display panel 10 includes a plurality of pixel circuits formed in a matrix shape, and each pixel circuit is connected to the data lines D1 -Dm formed in the column direction and the scan lines S1 -Sn formed in the row direction.

The scan driver 20 sequentially applies a selection signal to the plurality of scan lines S1 -Sn, and the data driver 30 applies a data signal to the plurality of data lines D1 -Dm.

The data driver 30 includes a plurality of DA converters DACs connected between the reference voltage supply line 50 and each of the data lines D1 -Dm, and the plurality of DA converters DACs are transferred from the reference voltage supply line 50. The digital image signal is converted into an analog data signal based on the voltage Vref.

However, when the data driver 30 is actually implemented, the reference voltage Vref transmitted from the power supply terminal 40 is changed to the reference voltage supply line 50 due to the internal resistances R1-R5 present in the reference voltage supply line 50. ), There was a problem of voltage drop.

Therefore, the reference voltage Vref applied to the DA converter is different depending on the connection position of the DA converter, so that a desired data signal is not applied to the data lines D1 -Dm.

An object of the present invention is to provide a light emitting display device and a display panel thereof by providing a predetermined reference power to a plurality of DA converters included in the data driver so that a desired data signal can be applied to a data line.

In accordance with one aspect of the present invention, a light emitting display device includes: a plurality of data lines for transmitting an analog data signal; A plurality of scan lines formed to intersect the data lines and transferring a selection signal; A plurality of pixel circuits configured to display an image corresponding to the data signal in response to the selection signal; A data driver for applying the data signal corresponding to the input digital image signal to the plurality of data lines; And first and second power supply terminals for supplying a reference voltage to the data driver, wherein the data driver includes a power supply line connected to the first and second power supply terminals, and the power supply line and the data line. And a plurality of DA converters connected to each other and converting the image signal into the data signal and applying the same to the data line.

In the light emitting display device according to an aspect of the present invention, the first and second power supply terminals supply the reference voltage at both ends of the data driver.

In the light emitting display device according to an aspect of the present invention, the DA converter includes a resistor string including at least one resistor connected to the power supply line and a second power source, and any one of terminals of the resistor included in the resistor string. A first switching element connected to one terminal and controlled on / off by the image signal, and connected to the other terminal of the terminal of the resistor included in the resistor string, and inverted by the inverted signal of the image signal. And a second switching element whose on / off is controlled, wherein the first and second switching elements are formed of transistors of the same channel type.

In the light emitting display device according to an aspect of the present invention, the first and second switching elements include a plurality of internal switching elements connected in series.

In the light emitting display device according to one aspect of the present invention, the data driver includes a shift register for sequentially shifting and outputting a start signal in synchronization with a clock signal and a signal output from the shift register. And a latch for latching and outputting the image signal in synchronization with the control unit, and a level shifter for changing the level of the signal output from the latch and inputting the signal to the DA converter.

According to an aspect of the present invention, there is provided a display panel including: a display area including a plurality of pixel circuits having a matrix shape and data lines for transmitting data signals to the pixel circuits; And a data driver for applying the data signal to the data line, wherein the data driver converts an image signal connected to the power supply line and an image signal connected to the power supply line to the data signal as an analog signal. And a plurality of DA converters applied to the data line.

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

In the following description, when a part is connected to another part, it includes not only the case where it is directly connected but also the case where it is electrically connected with another element between them. In the drawings, parts irrelevant to the present invention are omitted for clarity, and like reference numerals designate like parts throughout the specification.

2 illustrates a light emitting display device according to a first embodiment of the present invention.

As shown in FIG. 2, the light emitting display device according to the first embodiment of the present invention includes a display panel 100, a scan driver 200, and a data driver 300.

The display panel 100 includes a plurality of data lines D1 -Dm formed in a column direction, a plurality of scan lines S1 -Sn formed in a row direction, and a plurality of pixel circuits 11. The data lines D1-Dm transfer the data signal to the pixel circuit 11, and the scan lines S1-Sn transfer the selection signal to the pixel circuit 11. The pixel circuit 11 is formed in a pixel area defined by two neighboring data lines D1-Dm and two neighboring scan lines S1-Sn.

The scan driver 200 sequentially applies a selection signal to the scan lines S1 -Sn, and the data driver 300 applies a data voltage corresponding to the image signal to the data lines D1 -Dm.

Meanwhile, hereinafter, a digital signal input to the data driver 300 from the outside in order to display an image is called an image signal, and an analog signal corresponding to the digital image signal is called a data signal.

According to an embodiment of the present invention, the data driver 300 includes a shift register 310, a latch 320, a level shifter 330, and a DA converter (DAC) 340. The shift register 310 sequentially shifts and outputs the start signal VSP in synchronization with the clock signal VCLK.

The latch 320 latches and outputs an image signal input in synchronization with the signal output from the shift register 310, and the level shifter 330 changes and outputs the level of the signal output from the latch 320. In FIG. 2, the image signal is formed of 6 bits of digital data, and the latch 320 latches and outputs a 6 bit image signal in response to a signal output from the shift register 310.

The DA converter 340 generates an analog data signal corresponding to the digital signal output from the level shifter 330 and applies it to the data lines D1 -Dm. In addition, according to an embodiment of the present invention, power supply terminals 410 and 420 for transmitting a reference voltage Vref are connected to both ends of the DA converter 340.

The scan driver 200 and / or the data driver 300 may be electrically connected to the display panel 100 or may be attached to a tape carrier package (TCP) that is electrically attached to the display panel 100. It may be mounted in the form of a chip. Alternatively, the display panel 100 may be mounted in a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 100 in the form of a chip. Alternatively, the scan driver 200 and / or the data driver 300 may be directly mounted on the glass substrate of the display panel 100 or may be formed of the same layers as the scan line, the data line, and the thin film transistor on the glass substrate. It may be replaced with a circuit or directly mounted.

3 illustrates the internal configuration of the DA converter 340 of FIG. 2 in more detail.

As shown in FIG. 3, the DA converter 340 includes a plurality of sub DA converters 341-34m, and the sub DA converters 341-34m include the reference voltage supply line 430 and the data lines D1-Dm. ) Are connected.

Both ends of the reference voltage supply line 430 are connected to the power supply terminals 410 and 420, and transfer the reference voltage Vref applied from the power supply terminals 410 and 420 to each of the sub DA converters 341-34m. .

As described above, by applying the reference voltage Vref at both ends of the DA converter 340, the voltage drop of the reference voltage Vref due to the parasitic component present in the power supply line 430 can be suppressed.

FIG. 4 is a circuit diagram showing an internal configuration of the sub DA converter 341 shown in FIG. 4 illustrates a DA converter for inputting 2-bit digital data for convenience of description.

According to an embodiment of the present invention, the DA converter includes resistors R1-R4 and switching elements S10-S13 and S20-S23.

The resistors R1-R4 are connected in series between the power supply Vref and the power supply VSS to form a resistor string, and two switching elements are connected in series between the connection terminal and the output terminal between the resistors R1-R4.

Specifically, the switching elements S10 and S20 are connected in series between the power supply VSS side terminal of the resistor R1 and the output terminal, and the switching elements S11 and S21 are connected between the connection terminals of the resistors R1 and R2 and the output terminal. Are connected in series. In addition, the switching elements S12 and S22 are connected in series between the connection terminals of the resistors R2 and R3 and the output terminals, and the switching elements S13 and S23 are connected in series between the connection terminals of the resistors R3 and R4 and the output terminals. Is connected.

)가 인가되고, 스위칭 소자(S20-S23)에는 입력 신호(A₁)와 그 반전 신호(

)가 인가된다.The switching elements S10-S13 have an input signal A ₀ and an inverted signal thereof.

) Is applied to the switching elements S20-S23 and the input signal A ₁ and its inverted signal (

) Is applied.

As a result, the switching elements S10-S23 are turned on or off according to each bit value of the digital signal to be converted, thereby outputting an analog signal corresponding to the digital signal.

FIG. 5 is a circuit diagram illustrating the DA converter of FIG. 4 in more detail.

As shown in FIG. 5, all of the switching elements S10-S23 are formed of substantially the same type of transistors M10-M13 and M20-M23, and the gates of the transistors M10-M13 and M20-M23 The input signals A ₀ , A ₁ or the output signals of the inverters IN1, IN2 are applied.

)을 트랜지스터(M11, M13)의 게이트에 인가한다. 또한, 입력 신호(A₁)가 인가되는 신호선에 인버터(IN2)를 연결하여 입력 신호(A₁)를 반전시키고, 그 반전된 값(

)을 트랜지스터(M21, M23)가 게이트에 인가한다.Specifically, the inverter IN1 is connected to the signal line to which the input signal A ₀ is applied to invert the input signal A ₀ , and the inverted value (

) Is applied to the gates of the transistors M11 and M13. In addition, the inverter IN2 is connected to the signal line to which the input signal A ₁ is applied to invert the input signal A ₁ , and the inverted value (

) Is applied to the gates of transistors M21 and M23.

,

)를 스위칭 트랜지스터(M11, M13)와 스위칭 트랜지스터(M21, M23)의 게이트에 각각 인가함으로써, 모든 스위칭 소자를 서로 동일한 타입의 트랜지스터로 형성할 수 있다.In this way, the input signals A ₀ and A ₁ are applied to the gates of the switching transistors M10 and M12 and the switching transistors M20 and M22, respectively, and the inverted signals output from the inverters IN1 and IN2 (

,

) Are applied to the gates of the switching transistors M11 and M13 and the switching transistors M21 and M23, respectively, so that all the switching elements can be formed of transistors of the same type.

4 and 5 illustrate a DA converter for converting a 2-bit image signal into an analog data signal, but converting N-bit digital data such as 3 bits and 4 bits into an analog signal using the concept of the present invention. DA converters can be formed.

Specifically, in the case of converting an N-bit image signal to an analog signal, by connecting 2 ^N resistors in series and connecting N switching elements connected in series between the terminals and the output terminals of each resistor, the N bit DA converter Can be formed.

In some embodiments, the switching element may be connected to the terminal of the power supply VDD of the resistor R2 ^N without connecting the switching device to the terminal of the power supply VSS side of the resistor R1. The device can be connected.

4 and 5 alternately apply an input signal and an inverted signal to switching elements in the same column, but according to an embodiment, a plurality of switching elements formed in the same column are divided into two or more groups and included in the same group. The same signal can be applied to the switching element.

In this way, the inverter converts the input signal and applies the input signal or the inverted signal to the switching column, whereby the DA converter can be formed using only transistors of substantially the same type. As a result, the process of the DA converter is simplified, and the characteristics of the transistor are uniform, thereby improving the performance of the DA converter.

6 illustrates a light emitting display device according to a second embodiment of the present invention.

As shown in FIG. 6, the light emitting display device according to the second embodiment of the present invention differs from the light emitting display device according to the first embodiment of the present invention in that it includes two data drivers 300 and 500. Have

As shown in FIG. 6, when the data lines D1 -Dm are driven by using the two data drivers 300 and 500, the data lines D1 -Dm are divided into two groups, and the two groups are respectively data. The driving units 300 and 500 are driven.

In addition, the reference voltage Vref input from the power supply terminal 410 is input to one side of the data driver 300 and 500, and the reference voltage Vref input from the power supply terminal 420 is input to the data driver 300,. To the other side of 500).

Thus, when the dual data driver is used, the voltage drop of the reference voltage generated in the data driver can be suppressed, and the desired data signal is applied to the data line.

2 and 6 illustrate a case where the data signal applied to the data line is an analog current, but the concept of the present invention can be applied to a voltage write type light emitting display device as it is.

In the above, the light emitting display device and the display panel according to the exemplary embodiment of the present invention have been described. The above-described embodiment is an embodiment to which the concept of the present invention is applied, and the scope of the present invention is not limited to the above embodiment, and various modifications may be made by using the concept of the present invention as it is.

According to the present invention, by providing a constant reference power to a plurality of DA converters included in the data driver, it is possible to provide a light emitting display device and a display panel in which a desired data signal is applied to a data line.

Claims (7)

A plurality of data lines for transmitting analog data signals; A plurality of scan lines formed to intersect the data lines and transferring a selection signal; A plurality of pixel circuits configured to display an image corresponding to the data signal in response to the selection signal; A data driver for applying the data signal corresponding to the input digital image signal to the plurality of data lines; And First and second power supply terminals for supplying a reference voltage to the data driver Including; The data driver includes a power supply line connected to the first and second power supply terminals, and a plurality of DA converters connected between the power supply line and the data line to convert the image signal into the data signal and apply the data signal to the data line. A light emitting display device comprising a. The method of claim 1, The first and second power supply terminals supply the reference voltage at both ends of the data driver. The method of claim 1, The DA converter, A resistor string comprising at least one resistor connected to the power supply line and a second power source, A first switching element connected to any one of the terminals of the resistor included in the resistor row and controlled on / off by the image signal; and A second switching element connected to the other terminal of the terminals of the resistor included in the resistor row, the second switching element being turned on / off by an inversion signal of the image signal, The first and second switching devices are formed of transistors of the same channel type. The method of claim 3, The first and second switching elements include a plurality of internal switching elements connected in series. The method of claim 1, The data driver, A shift register for sequentially shifting and outputting a start signal in synchronization with a clock signal; A latch for inputting the image signal and latching and outputting the image signal in synchronization with a signal output from the shift register; And a level shifter for changing a level of a signal output from the latch and inputting the signal to the DA converter. A display area including a plurality of pixel circuits formed in a matrix shape and data lines for transmitting data signals to the pixel circuits; And A data driver for applying the data signal to the data line Including; The data driver includes a power supply line receiving power from both ends, and a plurality of DA converters converting an image signal connected to and input from the power supply line to the data signal as an analog signal. The method of claim 6, The DA converter may include: a resistor string including at least one resistor connected to the power supply line and a second power source; A first switching element connected to any one of the terminals of the resistor included in the resistor row and controlled on / off by the image signal; and A second switching element connected to the other terminal of the terminals of the resistor included in the resistor string, the second switching element being controlled on / off by an inversion signal of the image signal, And the first and second switching elements are formed of transistors of the same channel type.

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