This application claims the priority benefit of Taiwan Patent Application Serial Number 100136232 filed Oct. 6, 2011, the full disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a homeotropic alignment liquid crystal display with bias electrodes.
2. Description of the Related Art
The Liquid Crystal Display (LCD) has been broadly used in various applications in the daily life with the improvement and popularity of the digital network technology. Nowadays, the image quality of the LCD is nip and tuck with that of the Cathode Ray Tube (CRT) display. However, there are still some problems for the LCD needed to be improved and solved, such as the small viewing angle, the low contrast ratio, the long responding time, and the non-uniform displaying. Many techniques are developed for obtaining a wider viewing angle of the LCD. Among so many wide viewing angle techniques, the Multi-domain Vertical Alignment (MVA) techniques is one utilizing the properties of the non-identical directions in arrangements and rotations of the liquid crystal molecules to increase the viewing angle and shorten the responding time of the LCD.
The known vertical alignment technique is to align the liquid crystal molecules to be perpendicular to alignment films. Referring to
However, the fringe field of the pixel electrode 120 may cause disclination lines to occur in the liquid crystal molecules that are located at a side of the pixel. The disclination phenomena not only increase the responding time of the LCD but also cause the LCD to flicker.
Accordingly, there exists a need to provide a solution to solve the aforesaid problems.
The present disclosure provides a homeotropic alignment liquid crystal display with bias electrodes that may reduce the occurrence of disclination lines.
In one embodiment, the liquid crystal display of the present disclosure includes an upper substrate, a lower substrate, two data lines, two gate lines, a pixel electrode, a common electrode, a counter electrode, a homeotropic alignment liquid crystal layer, a first alignment film, a second alignment film, and a bias electrode. The data lines and gate lines are positioned on the lower substrate. The pixel electrode and common electrode are positioned on the lower substrate. The counter electrode is positioned on the upper substrate and faces the pixel electrode. The liquid crystal layer includes a plurality of liquid crystal molecules and is sandwiched between the upper and lower substrates. The first alignment film is positioned on the pixel electrode and is configured to align the liquid crystal molecules in a first alignment direction. The second alignment film is positioned on the counter electrode and is configured to align the liquid crystal molecules in a second alignment direction. When the liquid crystal molecules are free of being subjected to a voltage, the liquid crystal molecules are aligned perpendicular to the upper and lower substrates. When the liquid crystal molecules are subjected to a voltage, the liquid crystal molecules are aligned parallel to the upper and lower substrates and are twisted along the first alignment direction and the second alignment direction. The bias electrode is positioned on the lower substrate and at an edge of the pixel electrode, wherein the first alignment direction is toward the bias electrode. The bias electrode is configured to apply a bias voltage to the liquid crystal layer, wherein the bias voltage has a polarity the same as that of a voltage of the pixel electrode.
According to the present disclosure, wherein the bias voltage is greater than a voltage of the pixel electrode.
According to the present disclosure, wherein the bias electrode overlaps with a portion of the pixel electrode.
According to the present disclosure, wherein the bias electrode is positioned parallel to the data lines.
According to the present disclosure, wherein an angle formed between the first alignment direction and the second alignment direction is equal to or smaller than 90 degrees.
According to the present disclosure, wherein the liquid crystal display further includes an inverter configured to invert a polarity of and increase an amplitude of a voltage of the common electrode so as to generate the bias voltage on the bias electrode.
The foregoing, as well as additional objects, features and advantages of the disclosure will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.
a is an image of pixels in the liquid crystal display of the present disclosure when the bias electrodes are not activated.
b is an image of pixels in the liquid crystal display of the present disclosure when the bias electrodes are activated.
a is an image of pixels in the liquid crystal display of the present disclosure when the bias electrodes are not activated.
b is an image of pixels in the liquid crystal display of the present disclosure when the bias electrodes are activated.
Referring to
Referring to
According to the liquid crystal display 300 of the present disclosure, the liquid crystal molecules 335 assume a homeotropic alignment in the absence of an applied field. As shown in
In operation, the bias electrode 314 is used to apply a bias voltage Vbias to the liquid crystal layer 330. The bias voltage Vbias has a polarity the same as that of the voltage Vpixel of the pixel electrode 312 with reference to the voltage Vcom of the common electrode 318. In addition, the bias voltage Vbias is greater than the voltage Vpixel.
Referring to
According to the present disclosure, an inverter is further provided in the liquid crystal display 300 to invert a polarity and increase an amplitude of the voltage Vcom so as to generate the bias voltage Vbias on the bias electrode 314.
Referring to
As is seen from
Although the preferred embodiments of the disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims.
Number | Date | Country | Kind |
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100136232 | Oct 2011 | TW | national |