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Friday 19 June 2015

Liquid crystal display LCD

LCD


Liquid Crystal Display, abbreviations: LCD flat thin display device, by a number of color or monochrome pixel composition, placed in front of the light source or reflector side. Low-power liquid crystal display, so much favored by engineers, for battery of electronic equipment.

Each pixel of the liquid crystal display consists of the following parts: two layers of liquid crystal molecules suspended in a transparent electrode (indium tin oxide) between a columns outside on both sides with two mutually perpendicular polarization directions of the polarizing filters. If there is no liquid crystal between the electrodes, wherein the light through a polarizing filter whose polarization direction of the sheet, and the second polarizer perfectly vertical, and therefore is completely blocked. However, if the polarization direction of light through a polarizing filter sheet is rotating LCD, then it can be filtered through another polarizing sheet. Liquid crystal rotates the polarization direction of the light can be controlled by an electrostatic field, in order to achieve light control.

Liquid crystal molecules are easily affected by the induced charge arising from the applied electric field. A small amount of electric charge is applied to the transparent electrode of each pixel or sub-pixel to produce an electrostatic field, the liquid crystal molecules are induced by the electrostatic field induced charge and static torque, leaving the liquid crystal molecules are originally aligned to produce a rotating change, so also changed by rotating the amplitude of light. Changing the certain angle, it is possible through the polarization filters.

Before the charge applied to the transparent electrodes, the liquid crystal molecules are arranged to determine the alignment of the electrode surface, chemical surface electrode may be used as seed crystals. In the most common TN liquid crystal, the liquid crystal vertically aligned upper and lower electrodes. Liquid crystal molecules are spirally arranged, through a polarization filters rotated polarization direction of the light after passing through the LC panel, thereby through another polarizer. In this process, a small portion of the light blocked by the polarizer from the outside appears to be gray. After the charge is applied to the transparent electrodes, the liquid crystal molecules almost completely along the field direction are arranged in parallel, and therefore the direction of polarization of light through a polarizing filter sheet is not rotating, and therefore the light is completely blocked.