What is the structure of the LCD screen?

- Aug 14, 2018-



Without voltage, the light will travel along the gap of the liquid crystal molecules and turn 90 degrees, so the light can pass. However, after the voltage is applied, the light advances straight along the gap of the liquid crystal molecules, so the light is blocked by the filter. Liquid crystal is a substance with flow characteristics, so it is only necessary to add a very small force to move liquid crystal molecules. Taking the most common nematic liquid crystal as an example, liquid crystal molecules can easily turn liquid crystal molecules by electric field action, due to The optical axis of the liquid crystal is quite consistent with its molecular axis, so that an optical effect can be produced thereby, and when the electric field applied to the liquid crystal is removed, the liquid crystal will be very quickly retracted by its own elasticity and viscosity. The state before the electric field is added.


Each pixel of the liquid crystal display panel is composed of a liquid crystal molecular layer suspended between two transparent electrodes (indium tin oxide) and two polarizing filters having polarization directions perpendicular to each other on the outer sides. If there is no liquid crystal between the electrodes, the light passes through one of the polarizing filters and its polarization direction will be completely perpendicular to the second polarizing plate, and thus is completely blocked. However, if the direction of polarization of the light passing through a polarizing filter is rotated by the liquid crystal, it can pass through another polarizing filter.

Some liquid crystal displays turn black under the action of alternating current, and the alternating current destroys the spiral effect of the liquid crystal. After the current is turned off, the liquid crystal display will become bright or transparent. Such liquid crystal displays are commonly found on notebook computers and low-priced liquid crystal displays. Another type of liquid crystal display that is commonly used in high-definition LCD screens or large LCD TVs is that the liquid crystal display is opaque when the power is turned off.


In order to save power, the liquid crystal display adopts a multiplexing method. In the multiplexing mode, the electrodes at one end are grouped together, each group of electrodes is connected to one power source, and the electrodes at the other end are also connected in groups, and each group is connected to the power source. At the other end, the packet design ensures that each pixel is controlled by an independent power source, and the electronics or software that drives the electronics controls the display of the pixels by controlling the power on/off sequence.


The indicators for verifying the LCD include the following important aspects: display size, response time (synchronization rate), array type (active and passive), viewing angle, supported colors, brightness and contrast, resolution and aspect ratio, And input interfaces (such as visual interfaces and video display arrays).