The structure and working principle of liquid crystal display

Liquid crystal display, or LCD (Liquid Crystal Display), is a flat and ultra-thin display device, which consists of a certain number of color or black and white pixels, placed in front of a light source or reflector. Liquid crystal displays have very low power consumption, so they are highly favored by engineers and are suitable for electronic devices that use batteries. Its main principle is to stimulate the liquid crystal molecules to produce dots, lines, and surfaces with the back light tube to form a picture. In daily life, LCD displays can be seen everywhere, large screens for advertising on buildings, TV dramas at home, or smart phones and smart watches we use are all related to LCD display. As a major exporter of LCD displays, China has many excellent LCD display manufacturers. Sinda Display Technology Co., Ltd is obviously among them. Our company has many years of experience in LCD display production and we also have our own factories. , We are committed to high-quality product production and research and development.

(1) Physical characteristics of liquid crystal

The physical characteristics of liquid crystal are: when it is energized, it is turned on and the arrangement becomes orderly, making it easy for light to pass; when it is not energized, the arrangement is chaotic, preventing light from passing. Let the liquid crystal block or allow light to penetrate like a gate. Technically speaking, the LCD panel contains two very delicate soda-free glass materials, called Substrates, with a layer of liquid crystal in between. When the light beam passes through this layer of liquid crystal, the liquid crystal itself will stand in rows or twist in an irregular shape, thus blocking or allowing the light beam to pass smoothly. Most liquid crystals are organic compounds, composed of long rod-shaped molecules. In the natural state, the long axes of these rod-shaped molecules are roughly parallel. When the liquid crystal is poured into a well-processed slotted plane, the liquid crystal molecules will be arranged along the grooves, so if the grooves are very parallel, the molecules are also completely parallel.

(2) The principle of monochrome liquid crystal display

LCD technology is to pour liquid crystal between two planes lined with fine grooves. The grooves on these two planes are perpendicular to each other (intersect at 90 degrees). In other words, if the molecules on one plane are arranged north-south, the molecules on the other plane are arranged east-west, and the molecules between the two planes are forced into a 90-degree twisted state. Since the light travels along the direction of the molecular arrangement, the light is also twisted 90 degrees when passing through the liquid crystal. But when a voltage is applied to the liquid crystal, the molecules will be re-arranged vertically, so that the light can be directed out without any twisting.

LCD relies on polarization filters (plates) and light itself. Natural light diverges randomly in all directions. The polarization filter is actually a series of increasingly thinner parallel lines. These lines form a net, blocking all light that is not parallel to these lines. The line of the polarization filter is exactly perpendicular to the first one, so it can completely block the polarized light. Only when the lines of the two filters are completely parallel, or the light itself has been twisted to match the second polarized filter, the light can penetrate.

LCD is composed of two polarizing filters that are perpendicular to each other, so under normal circumstances, all light that attempts to penetrate should be blocked. However, because the two filters are filled with twisted liquid crystals, after the light passes through the first filter, it will be twisted 90 degrees by the liquid crystal molecules, and finally pass through the second filter. On the other hand, if a voltage is applied to the liquid crystal, the molecules will rearrange and be completely parallel, so that the light is no longer twisted, so it happens to be blocked by the second filter. In short, power is applied to block the light, and no power is applied to cause the light to be emitted.However, the arrangement of the liquid crystals in the LCD can be changed so that light is emitted when power is applied, but is blocked when power is not applied. But because the computer screen is almost always on, only the "power-on and block the light" solution can achieve the most power-saving purpose.

(3) Working principle of color LCD display

For the more complex color monitors that laptops or desktop LCD monitors need to adopt, it is also necessary to have a color filter layer that specializes in color display. Generally, in a color LCD panel, each pixel is composed of three liquid crystal cells, and each cell has a red, green, or blue filter in front of it. In this way, the light passing through different cells can display different colors on the screen. LCD overcomes the shortcomings of CRT's bulkiness, power consumption, and flicker, but it also brings problems such as high cost, low viewing angle, and unsatisfactory color display. CRT display can choose a series of resolutions, and can be adjusted according to the requirements of the screen, but the LCD screen only contains a fixed number of liquid crystal cells, can only use one resolution display on the full screen (each cell is a pixel).

(4) Application and new technology of liquid crystal display

Driven by TFT type Active element：In order to create a better picture structure, the new technology uses a unique TFT-type Active element for driving. Everyone knows that the most important part of an extremely complex LCD screen is the liquid crystal, it is the backlight screen that is directly related to the brightness of the liquid crystal display and the color filter that is responsible for producing colors. Active elements are added to each liquid crystal pixel for point-to-point control, which makes the display screen very different from the full-scale CRT display. This control mode is better than the previous control method in terms of display accuracy. It is much higher, so the image quality is poor, color bleeding and jitter are very serious on the CRT display screen, but the picture quality is quite pleasing when viewed on the LCD display with the new technology.

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