KR100667184B1 - Source driver of liquid crystal display - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a source driving device of a liquid crystal display device. According to the present invention, a source driving device of a liquid crystal display device having a liquid crystal display panel includes a plurality of odd outputs connected to the display panel and alternately arranged with each other. A plurality of positive amplifiers arranged in a number corresponding to the terminals and even output terminals and the odd output terminals, and connected to the odd output terminals through odd lines, and arranged in a number corresponding to the even output terminals. A plurality of negative amplifiers connected to the even output terminals, a plurality of capacitors respectively connected to the odd lines and the even lines through a first switch, and a second switch connecting the capacitors to each other; The odd output terminal and the even output terminal output a constant voltage regardless of an input voltage. The source driving device of a liquid crystal display device is provided, characterized in that operative to. According to the present invention, the output voltage of the plurality of output lines of the source driver is constantly fixed regardless of the input voltage when the source driver is driven by the control of the switch, thereby maintaining power storage efficiency.

Description

Source driver of liquid crystal display {Source driver of liquid crystal display}

1 is a block diagram of a general liquid crystal display device.

2 is a channel structure diagram of a conventional charge sharing TFT LCD source driver.

3 is a channel structure diagram of a charge sharing TFT LCD source driver according to the present invention.

4 is a signal waveform diagram of the source driver of FIG. 3.

[Description of Symbols for Main Parts of Drawing]

21. Inverters sw1 to sw4. switch

33.MUX 36. High Capacity Capacitors

31.Positive Amplifiers 32.Negative Amplifiers

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a source driving device of a liquid crystal display device, and more particularly, to a source driving device of a liquid crystal display device in which power consumption is reduced by always fixing a common output voltage of a plurality of output channels independently of an input when sharing charges. .

Liquid crystal displays (LCDs) consume less power and consume less area than CRTs. Among them, an active matrix liquid crystal display (liquid crystal display device) using TFT (Thin-Film-Transistor) has high precision, is capable of large screens, and is used for various purposes such as a personal computer display or a television screen.

In an active matrix display, TFTs are arranged in a matrix form on this display panel. These TFTs are normally controlled by a driver IC disposed in the frame portion of the display panel. The driver IC includes a source driver and a gate driver. The operation of these driver ICs is controlled by signals output from the controller. The controller generates various signals including the clock signal to perform appropriate control.

In the above-mentioned active matrix system, in recent liquid crystal display devices, control of dot inversion driving is executed for the purpose of preventing long-term image persistence of liquid crystals.

In the present specification, an element including a TFT, a liquid crystal capacitor, or a light emitting element, and the element for displaying one dot on the display panel is called a pixel (pixel), and constitutes one pixel, and each color such as red, green, and blue Each element for displaying is referred to as a subpixel.

1 is a block diagram of a general liquid crystal display device.

In the general liquid crystal display device 1, a subpixel having a TFT and a liquid crystal capacitor is disposed, a display panel 6 for displaying an image, and all are arranged in the display panel 6, and scanning lines for driving the subpixel ( 2) and signal line 3, gate driver 4 for supplying voltage to scan line 2, source driver 5 for supplying voltage to signal line 3, gate driver 4 and source A controller 7 is provided for controlling the operation of the driver 5. The source driver 5 also has charge recovery means 22 for connecting the output portions adjacent to each other for a predetermined period of time. The signal line 2 and the scan line 3 cross each other, and the subpixels are arranged in a matrix on the display panel.

2 is a channel structure diagram using a charge sharing method of a conventional TFT LCD source driver.

Referring to Fig. 2, the source driving circuit includes an odd output terminal 24 for outputting video signal voltages of odd data lines (hereinafter referred to as odd lines) and even data lines (hereinafter referred to simply as even lines). Even output terminals 25, switches 22 and 23 for controlling the connection of the odd output terminal 24 and the even output terminal 25, and control signals for controlling these switches 22 and 23 are inputted. The inverter 21 is connected to the control terminal CR and the control terminal CR, and is connected to a switch 22 for switching the connection between the odd input terminal 24 and the even input terminal 25 with the data line. .

Inverted control signals are inputted from the control terminal CR to the switch 22 and the switch 23 through the inverter 21.

A predetermined period of time is executed between output terminals of adjacent source drivers. When electrically connected between adjacent output terminals, the electric potential of both output terminals changes in the direction which averages. The operation of electrically connecting the two or more output terminals is defined as charge sharing.

However, in the conventional source driver, the common output voltage Vcom of the multiple outputs varies according to the input voltage value.

Accordingly, there is a problem in that power consumption increases because the power storage efficiency cannot be constantly maintained at a value of 50%.

Meanwhile, the TFT LCD source driver has been developed so far with low power consumption, high quality, and low cost, but it can be implemented with technology and low cost that can provide stable and high quality images while reducing power consumption. Development of a TFT LCD driver is desired.

The present invention has been made to solve the above problems, TFT LCD driving device that maintains a constant constant output voltage (Vcom) value of the VDD / 2 voltage value at the time of charge sharing, and makes the power storage efficiency 50% The purpose is to provide.

In order to achieve the above object, according to the present invention, in the source driving apparatus of the liquid crystal display device having a liquid crystal display panel, a plurality of odd output terminals and even output terminals connected to the display panel and arranged alternately, A plurality of positive amplifiers arranged in a number corresponding to the odd output terminals and connected to the odd output terminals through odd lines, and arranged in a number corresponding to the even output terminals and connected to the even output terminals through even lines; A plurality of negative amplifiers, a plurality of capacitors connected to each of the odd lines and the even lines through a first switch, and a second switch connecting the capacitors to each other, wherein the odd output terminals and the The even output terminal operates to output a constant voltage regardless of the input voltage. The source driving device of a liquid crystal display device is provided.

Here, when the first switch is high, the second switch is preferably low.

Further, a third switch for turning on / off the connection between the positive amplifier and the odd output terminal and turning on / off the connection between the negative amplifier and the even output terminal, and outputs the positive amplifier, the negative amplifier, and the front end. It is further preferred to further comprise a fourth switch for turning on / off the connection between the terminals.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

3 is a block diagram of a source driver according to the present invention.

Referring to FIG. 3, a source driver according to the present invention may include a plurality of positive rail-to-rail amplifiers (hereinafter, referred to as positive amplifiers) 31 to which voltages are input from an input terminal V1, and voltages from an input terminal V2. A plurality of negative rail-to-rail amplifiers (hereinafter referred to as negative amplifiers) 32 to be input, a plurality of switches sw3 and a plurality of switches sw4 connected to the respective positive amplifiers 31 and the negative amplifiers 32, Odd-numbered output terminals 34 connected to the positive amplifier 31 and the negative amplifier 32 through a plurality of MUX 33, switches sw3, and MUX 33 connected to the respective switches sw3 and sw4, and The even output terminal 35, the switch sw1 for switching the on / off control of the MUX 33, the capacitor 36 and the switch sw1 connected between the ground line and the switch sw1 operate inverted, and the capacitor ( Consisting of a switch sw2 connected therebetween, and driven on the LCD display panel 6 Apply voltage.

The plurality of positive amplifiers are arranged by the number corresponding to the odd output terminals, and the plurality of negative amplifiers are arranged by the number corresponding to the even output terminals.

In other words, odd lines and even lines were connected to each other using only odd lines, and even lines were connected in the same manner. The two high capacitance capacitors 36 were connected to the two lines connected in this way, and the two high capacitance capacitors were connected to the switch sw2. Control signals from the controller 7 are input to these switches sw1 to sw4.

A positive voltage is applied to the positive amplifier 31 and a negative voltage is applied to the negative amplifier 32 for line inversion.

The positive amplifier 31 receives a voltage source of VDD-0.2V as an input, and the negative amplifier 32 receives a voltage source of GND + 0.2V as an input, and each comprises a buffer for generating an analog voltage.

Hereinafter, the output voltage waveform in the low power source driving method according to the present invention will be described in detail with reference to FIG. 4.

The signal generated from the controller 7 is divided into a charge sharing section and a driving section.

1)는 제어기(7)로부터 들어오는 로드 신호와 같은 신호로 온/오프 동작을 하면서 내부 기생 캐패시터(도시 생략)와 외부의 고용량 캐패시터(36)의 전하를 공유시키는 동작을 한다. Switch (sw1:

1) performs an on / off operation with a signal such as a load signal coming from the controller 7, and shares an electric charge of the internal parasitic capacitor (not shown) with the external high capacity capacitor 36.

1)는 로드 신호의 반전신호에 의해 동작하면서 전하공유 구 간동안 저장한 전하를 구동 구간동안 외부의 고용량 캐패시터의 전하를 공유시키는 동작을 한다. Switch (sw2,

In operation 1), the charge stored in the charge sharing section is shared by the charge of the external high capacity capacitor during the driving section while operating by the inverted signal of the load signal.

2)는 포지티브 증폭기(31)에서 발생한 아날로그 출력으로 표시패널(6)을 구동시키고, 스위치(sw4,

3)는 네가티브 증폭기(32)에서 발생한 아날로그 출력으로 표시패널(6)을 구동시킨다.Switch (sw3,

2) drives the display panel 6 with an analog output generated from the positive amplifier 31, and switches sw4,

3) drives the display panel 6 with the analog output generated by the negative amplifier 32.

1의 스위치 컨트롤 신호가 동작하고,

1의 스위치 컨트롤 신호는 로드 신호의 반전된 신호를 발생하게 된다.First, the load signal entering the gate driver 4 from the controller 7 is divided into a charge sharing section and a driving section. In line with this load signal

1 switch control signal is activated,

A switch control signal of 1 will generate an inverted signal of the load signal.

1의 신호가 하이(H)일때

1의 신호는 로우(L)가 되면서 표시패널(6)에 연결된 소스 라인(3)은 표시패널(6)의 캐패시턴스(도시 생략)와 연결이 되고 외부의 고용량 커패시터(36)는 홀수 라인과 짝수 라인에 서로 연결되고 두 개의 커패시터(36)간의 연결은 오픈된다.

When signal of 1 is high (H)

The signal of 1 becomes low (L) and the source line 3 connected to the display panel 6 is connected to the capacitance (not shown) of the display panel 6, and the external high capacitance capacitor 36 is even and odd lines. The lines are connected to each other and the connection between the two capacitors 36 is open.

At this time, the charges of the parasitic capacitance load in the display panel 6 are divided and charged in the capacitors 36 connected to the odd lines and the even lines, respectively.

1)는 로우가 되고, 스위치(

1)가 H로 되는 순간 포지티브 증폭기(31)와 패널의 홀수 라인을 연결해 주는 스위치(sw3)는 도 4에 나타낸 바 와 같이 하이로 된다. And switch (

1) goes low, and the switch (

As soon as 1) becomes H, the switch sw3 connecting the positive amplifier 31 and the odd line of the panel becomes high as shown in FIG.

1)는 오픈이 되고, 외부의 고용량 커패시터를 연결해 주는 스위치(

1)와 홀수 라인 및 짝수 라인과 표시패널(6)을 연결해주는 스위치(

2)가 단락되게 된다. In this case, the switch connects only odd and even lines to an external capacitor.

1) is open, a switch that connects an external high-capacitor

1) and odd line and even line and the switch to connect the display panel (6)

2) is short-circuited.

As a result, while the positive buffer amplifier 31 and the negative buffer amplifier 32 drive the panel, the charges charged in the external high capacity capacitors 36 are shared to have a voltage value of VDD / 2.

At this time, the positive buffer amplifier 31 generates P (positive video signal) as shown in the output waveform of FIG. 4, and the negative buffer amplifier 32 generates N (negative video signal).

1)가 H이고, 스위치(

1,

2)가 로우이며, 그리고 스위치(

3)가 로우를 그대로 유지한 상태가 된다.Then, the operation signal of the switches is a switch (

1) is H, switch (

One,

2) is low, and the switch (

3) is in a state of keeping a low.

1)만이 단락되어 패널과 외부의 고용량 커패시터를 연결시켜줌으로서 외부의 고용량 커패시터에 충전된 전하들이 표시 패널(6)의 내부에 캐패시턴스 로드의 전하와 공유하면서 출력파형의 전압을 Vcom 전압 즉, VDD/2값으로 만들어주게 된다. In this case, the display panel 6 connected to the source line, that is, the odd line and the even line is opened, and the switch (

1) Only the short-circuit connects the panel and the external high-capacitance capacitor so that the charges charged in the external high-capacitance capacitor share the charge of the capacitance load inside the display panel 6 and share the voltage of the output waveform with the Vcom voltage, that is, VDD / It will make it 2 values.

That is, since the charge of the high capacity capacitor 36 and the charge of the capacitance load inside the display panel 6 are shared, the Vcom voltage of the output waveform is always VDD / V regardless of the input voltage values entering the buffer amplifiers 31 and 32. 2 Keep it at the voltage value.

So the power storage efficiency is always 50% independent of the input voltage value.

1)가 로우이고, 스위치(

1,

3)가 하이이며, 그리고 스위치(

2)가 L로 되는 구간동안 표시패널(6)과 오픈된 고용량 커패시터들(36)은 다시 전하공유를 하게 된다.Finally, switch (

1) is low and the switch (

One,

3) is high, and the switch (

During the period in which 2) becomes L, the display panel 6 and the open high capacitance capacitors 36 share charges again.

At the same time, the positive buffer amplifier 31 generates N (negative video signal) as opposed to the previous step, and the negative buffer amplifier 32 drives the panel while generating P (positive video signal).

Therefore, the common output voltage Vcom of the multiple outputs is constantly fixed to the voltage value of VDD / 2 through switch control when driving the source driver.

According to the present invention, the output voltage of the plurality of output lines of the source driver is constantly fixed regardless of the input voltage when the source driver is driven by the control of the switch, thereby maintaining power storage efficiency.

Thus, the power consumption of the LCD source driver, which occupies a considerable portion when driving the TFT LCD, is reduced.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.

Claims (4)

In the source driving device of the liquid crystal display device provided with a liquid crystal display panel, A plurality of odd output terminals and even output terminals connected to the display panel and alternately arranged; A plurality of positive amplifiers arranged by a number corresponding to the odd output terminals and connected to the odd output terminals through odd lines; A plurality of negative amplifiers arranged by a number corresponding to the even output terminals and connected to the even output terminals through an even line; A plurality of capacitors connected to the odd lines and the even lines through a first switch, and a second switch connecting the capacitors to each other; A third switch for turning on / off a connection between the positive amplifier and the odd output terminal and turning on / off a connection between the negative amplifier and the even output terminal; A fourth switch for turning on / off a connection between the positive amplifier and the negative amplifier and the output terminal of the previous stage; When the first switch is high, the second switch is controlled low to operate the odd output terminal and the even output terminal to output a constant common voltage regardless of the input voltage. Source driving device of liquid crystal display device. delete delete The method of claim 1, When the first switch is high, the capacitors are connected to each other on the odd and even lines, the connection between the two capacitors is open, the capacitor is charged, When the first switch is low, the positive amplifier and the odd output terminal are connected, the negative amplifier and the even output terminal are connected, and the capacitor is opened between the odd line and the even line, While the positive amplifier and the negative amplifier drive the display panel, the charges charged in the capacitors are shared to output a constant common voltage to the odd output terminal and the even output terminal. Device.

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