KR20090059627A - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display for being displayed into low power consumption is provided to display the text of an electronic book or electronic paper by arranging a capacitor in a memory of a pixel area of a liquid crystal display. A liquid crystal display comprises a gate line(4), a pair of data lines, a first and second memory switching element, a first and second memory and a liquid crystal layer. The gate line and a pair of data lines are crossed and arranged. First and second memory switching elements are arranged in the liquid crystal pixel. First and second memories are connected to the first and second memory switching element. Supplied voltages are selected by the first selection switching element and the second selection switching element according to the voltage charged in the first memory and the second memory. The liquid crystal layer is driven by the voltage supplied through the first selection switching element and the second selection switching element.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device that can display with low power consumption.

Electrophoretic Display devices require no external light source, have excellent reflectivity, have excellent flexibility, portability, and other light weight characteristics such as electrophoresis. It is a kind of flat display using the phenomenon that particles move toward the anode or cathode.

The electrophoretic display device is a reflective display which drives an electrophoretic suspended particle by applying a transparent conductive film to a thin, bendable base film such as paper or plastic, and is a next generation electric paper. As a device that is expected to be in the spotlight. In addition, the electronic paper is very clear, has a wide viewing angle, and there is a memory function that does not completely disappear even in the absence of power.

These great advantages make electronic papers in a wide range of applications, including paper-like faces and e-books with moving illustrations, self-renewable newspapers, reusable paper displays for mobile phones, disposable TV screens and electronic wallpaper. There is a huge potential market.

The technical approach for the electronic paper implementation includes a liquid crystal method, an organic EL, a reflective film reflective display, an electrophoresis, a twist ball, an electrochromic method, and a mechanical reflective light. In particular, due to the development of a liquid crystal display device (Liquid Crystal Display Device), a method for implementing electronic paper using a liquid crystal has been recently developed.

However, there are many problems to implement an electronic paper or an electronic book by applying a driving method of a TFT (Thin Film Transistor) liquid crystal display.

For example, the liquid crystal display maintains a still image for a long time due to a fast refresh time and a voltage holding ratio in the pixel to improve the DC stress of the liquid crystal. High power consumption is inevitable when applied to electronic paper or electronic books.

An object of the present invention is to provide a liquid crystal display device capable of displaying an electronic paper or text of an electronic book with low power consumption by disposing a capacitor serving as a memory in a pixel area of the liquid crystal display device.

According to an aspect of the present invention, there is provided a liquid crystal display device including: a gate line and a pair of data lines arranged to cross each other to define a liquid crystal pixel; First and second memory switching elements disposed in the liquid crystal pixel; First and second memories connected to the first and second memory switching devices, respectively; First and second selection switching elements for selecting voltages supplied according to voltages charged in the first and second memories; And a liquid crystal layer driven by a voltage supplied through the first selective switching element and the second selective switching element.

As described in detail above, the present invention has the effect of disposing a capacitor that acts as a memory in the pixel area of the liquid crystal display device to display electronic paper or text of an electronic book with low power consumption.

In addition, according to the present invention, all the switching elements formed in the pixel region can be manufactured using N-type transistors, and thus an effect of manufacturing a pixel array capable of displaying electronic paper or electronic books without additional processes to the existing liquid crystal display manufacturing process can be obtained. have.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. First, it should be noted that the same components or parts in the drawings represent the same reference numerals as much as possible. In describing the embodiments, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the gist of the embodiments.

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

1 is a view showing the structure of a liquid crystal display according to the present invention, Figures 2a and 2b is a waveform diagram for explaining a driving method of the liquid crystal display according to the present invention.

1, 2A and 2B, the liquid crystal display according to the present invention includes a gate driver 4 and a data driver 3 electrically connected to the liquid crystal display panel 1; A data controller 5 for controlling the operation of these drivers 4, 3; And a power supply unit 6 for supplying a control signal to the sub pixel region (liquid crystal pixel region) of the liquid crystal display panel 1.

In the liquid crystal display panel 1, the gate lines GL1 to GLn and the data lines DL1 + and DL1 -... cross each other to divide sub-pixel regions. Liquid crystal pixels are formed in each of the plurality of sub pixel regions. In addition, between the gate lines GL1 to GLn, a reference voltage line for supplying a reference voltage Vref for driving elements disposed in the liquid crystal pixel, liquid crystal retention, and dc stress reduction are In order for the refresh pulse line supplying the refresh pulse voltage and the Vcom voltage line supplying the common voltage Vcom to cross the data lines DL1 +, DL1 -... Is placed. In addition, in the liquid crystal display of the present invention, a pair of data lines are arranged to supply a positive gray voltage and a negative gray voltage to one liquid crystal pixel.

When data information to be displayed is supplied to the data controller 5, the data controller 5 determines the position at which the data information is to be displayed and the voltage to be applied. Data input to the liquid crystal pixels of the liquid crystal display panel 1 is divided into "high" or "low" (logical signals 1 or 0), and 5V for "high", 0V or "for low". High "is 10V, and" Low "is 5V. However, this may vary depending on the voltage magnitude to drive the liquid crystal of the liquid crystal display panel 1, not the fixed voltage.

As shown in FIG. 2A, when the "high" data gray voltage data + and the "low" data gray voltage data- are supplied to the liquid crystal pixel, and the gate driving voltage Gn is input to the designated address, the liquid crystal pixel As the first memory switching device T1 and the second memory switching device T2 of the turn-on state are turned on, respectively, the "high" data gray voltage is charged in the first memory C1 and the "low" in the second memory C2. "Data gradation voltage is charged.

As a result, in the liquid crystal pixel region, the first selection switching device T3 is turned on by the first memory C1 charged with the “high” data gray voltage, and the second memory C2 charged with the “low” data gray voltage. ), The second selection switching device T4 is turned off. In this case, a positive / negative polarity (V + / V−) voltage for driving the liquid crystal is applied to the liquid crystal pixel through a reference voltage line connected to the first selective switching element T3. The common voltage line is connected to the source electrode of the second selective switching element T4, but the second selective switching element T4 is turned off to the "low" voltage charged in the second memory C2 so that the common voltage is the liquid crystal. It is not applied to the pixel. Therefore, the liquid crystal pixel is controlled by the positive and negative reference voltages Vref to display the text.

However, in the liquid crystal display panel 1, it is difficult to keep the liquid crystal for a long time, and a refresh voltage is periodically applied to the liquid crystal pixel region. When the refresh voltage is periodically applied to the liquid crystal pixel in accordance with the period in which the reference voltage is supplied, the first connection switching element T5 and the second connection switching element T6 disposed in the liquid crystal pixel are turned on.

In this case, the first connection switching device T5 is turned on and the reference voltage applied through the first selection switching device T3 is supplied to the liquid crystal capacitor Clc. Since the second selection switching device T4 is turned off, no other voltage is applied even when the second connection switching device T6 is turned on.

In addition, when the "low" data gradation voltage is charged in the first memory C1 and the "high" data gradation voltage is charged in the second memory C2, the first selection switching device T3 is turned off. And the second selection switching device T4 is turned on.

As a result, the common voltage Vcom is applied to the liquid crystal pixel through the common voltage line electrically connected to the second selection switching element T4, thereby displaying the black state.

 As shown in FIG. 2B, when the refresh voltage is periodically supplied to the liquid crystal display panel 1 being displayed, the positive pixel voltage Vp and the negative pixel voltage are applied to the liquid crystal pixel area based on the common voltage Vcom. (Vp) was repeatedly supplied to solve the problem caused by the liquid crystal DC stress.

That is, the liquid crystal pixel region is constantly displayed by the supplied reference voltage, but the liquid crystal used in the liquid crystal display panel 1 does not operate smoothly when dc is continuously applied for a certain period of time. To solve this problem, the refresh voltage was periodically supplied to alternate the positive and negative voltage polarities, thereby solving problems such as deterioration of the liquid crystal due to DC stress.

In addition, in the present invention, all the switching elements in the liquid crystal pixel region can be formed by the N-type TFT, and thus there is an advantage in that the array substrate can be formed by applying the manufacturing process of the existing liquid crystal display device as it is.

3 is a block diagram illustrating a data processing process of a liquid crystal display according to the present invention.

Referring to FIG. 3, when data information to be displayed from an external system such as a graphics card is supplied to the data input unit 11 provided in the data controller 5, the data input unit 11 may use the liquid crystal display panel based on the supplied data information. Set the position to be displayed on the screen, and set the data refresh time. In this case, data values supplied to the liquid crystal pixel area of the liquid crystal display panel are set.

The data information set by the data setting unit 12 is stored in the memory 13, and the stored data information is disposed on the liquid crystal display panel through the data setting unit 12 and the gate driver 4. Supplied to.

The data driver 3 and the gate driver 4 display the desired text by supplying the data gray voltage and the driving voltage to the liquid crystal pixel using the supplied setting data information.

4 is a diagram illustrating a structure of a liquid crystal display according to another exemplary embodiment of the present invention.

Referring to FIG. 4, unlike FIG. 1, the refresh voltage line is deleted so that the refresh voltage is not separately applied to the liquid crystal display panel 1. The same reference numerals as in FIG. 1 refer to the same components, and thus detailed description thereof will be omitted.

The liquid crystal pixel region of the liquid crystal display panel 1 is defined by a pair of data lines DL1 + and DL1- and a gate line GL1, and includes a first memory switching element T1 and a second memory switching element T2. The gate electrode of is connected to the gate line in common.

In addition, the source electrodes of the first selective switching element T3 and the second selective switching element T4 are connected to a reference voltage line and a common voltage line, respectively. The drain electrodes of the first selective switching element T3 and the second selective switching element T4 are commonly connected to the liquid crystal capacitor Clc.

Therefore, when the signal waveform shown in FIG. 2A is supplied, the first memory C1 is charged with the "high" data gradation voltage, and if the second memory C2 is charged with the "low" data gradation voltage, the first The selection switching device T3 is turned on and the second selection switching device T4 is turned off. Therefore, the reference voltage having positive / negative polarity is supplied to the liquid crystal capacitor through the first selective switching element T3. Since the reference voltage itself swings the positive electrode and the negative electrode alternately, the voltage supplied to the liquid crystal capacitor Clc is alternately changed between the positive electrode and the negative electrode so that the liquid crystal deterioration is not caused by the DC stress.

In addition, when the "low" data gradation voltage is charged in the first memory C1 and the "high" data gradation voltage is charged in the second memory C2, the first selection switching device T3 is turned off, and The two-selection switching element T4 is turned on.

Therefore, the common voltage connected to the source electrode of the second selective switching element T4 is supplied to the liquid crystal capacitor Clc to become the black state of the liquid crystal display panel 1.

FIG. 5 is a diagram for describing a gray scale expression method by dividing an area of a sub pixel according to another exemplary embodiment.

Referring to FIG. 5, when the liquid crystal pixels of the liquid crystal display panel are driven only in black and white according to FIGS. 1 and 4, various gray level representations are difficult.

Therefore, in the present invention, the red, green, and blue subpixels are defined as nine unit blocks, and then the first red subpixel R sub pixel_1, the second red subpixel R sub pixel_2, and the third red subpixel R are defined. The area of the sub pixel_3 is different from each other Similarly, the first green sub pixel G sub pixel_1, the second green sub pixel G sub pixel_1, and the third green sub pixel G sub pixel_1 and the first blue sub sub are similarly formed. The areas of the pixel B sub pixel_1, the second blue sub pixel B sub pixel_1, and the third blue sub pixel B sub pixel_1 are designed differently.

As shown in the figure, the area of the third red, green, and blue sub-pixels is formed to be the largest, and the area of the first red, green, and blue sub-pixels is formed to be smaller than that of the first red sub-pixel. 2 The area of the red, green and blue sub-pixels is formed to be the smallest. As described above, in the case of area division, the liquid crystal is driven only by black and white in each sub pixel area, but various gray levels can be expressed by arranging sub pixels having different areas in one unit block.

The area division sub-pixels shown in FIG. 5 are merely exemplary, and the area may be variously adjusted, and the number of sub-pixels included in the unit block may be variously adjusted to 9, 12, 15, and the like. have.

1 is a view showing the structure of a liquid crystal display according to the present invention.

2A and 2B are waveform diagrams for describing a method of driving a liquid crystal display according to the present invention.

3 is a block diagram illustrating a data processing process of a liquid crystal display according to the present invention.

4 is a diagram illustrating a structure of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 5 is a diagram for describing a gray scale expression method by dividing an area of a sub pixel according to another exemplary embodiment.

* Description of the symbols for the main parts of the drawings *

1: liquid crystal display panel 3: data driver

4: gate driver 5: data controller

6: power supply

Claims (5)

A gate line and a pair of data lines intersected with each other to define a liquid crystal pixel; First and second memory switching elements disposed in the liquid crystal pixel; First and second memories connected to the first and second memory switching devices, respectively; First and second selection switching elements for selecting voltages supplied according to voltages charged in the first and second memories; And And a liquid crystal layer driven by a voltage supplied through the first selective switching element and the second selective switching element. The liquid crystal display of claim 1, further comprising a first connection switching element and a second connection switching element for adjusting a supply of a refresh voltage for maintaining a voltage applied to the liquid crystal layer. The method of claim 1, wherein the first selective switching device is electrically connected to a line to which a reference voltage for driving the liquid crystal is supplied, and the second selective switching device is electrically connected to a line to which a common voltage is supplied to not drive the liquid crystal. Liquid crystal display, characterized in that connected to. The liquid crystal display device according to claim 1, wherein the switching elements are of the same type transistor. The liquid crystal display device according to claim 1, wherein the switching elements are N-type transistors.

Images