LCD technology application

April 13, 2022

Whether it is a notebook computer or an industrial LCD screen, the LCD display used is a layered structure composed of different parts. The rearmost layer is a backlight layer made of phosphors that emits light. The light emitted by the backlight layer enters the liquid crystal layer containing thousands of crystal droplets after passing through the first polarizing filter layer. The crystal droplets in the liquid crystal layer are all contained in tiny cell structures, one or more of which make up a pixel on the screen. When the electrodes in the LCD generate an electric field, the liquid crystal molecules will be twisted, so that the light passing through it will be refracted regularly, and then filtered by the second filter layer and displayed on the screen.

Industrial LCD screens are displays used in industrial control processes or equipment. The main difference between it and civilian or commercial monitors is that the shell design generally adopts an all-steel design, and the panel is divided into different materials such as ordinary iron plate, stainless iron, stainless steel, aluminum panel, etc. Liquid crystal display, in the case of high environmental requirements, consider using a wide temperature (-40 to 85 degrees) liquid crystal display, so the industrial LCD screen is more expensive in the market.

For simple monochrome LCD displays, such as those used in PDAs, the above configuration is sufficient. But for the more complex color displays used in notebook computers, a color filter layer dedicated to color display is also required. Typically, in a color LCD panel, each pixel consists of three liquid crystal cells, each of which is preceded by a red, green, or blue filter. In this way, light passing through different cells can display different colors on the screen. Almost all LCDs used in notebook or desktop systems use thin-film transistors (TFTs) to activate the cells in the liquid crystal layer. TFT LCD technology can display clearer, brighter images. LCDs in the 1960s and 1970s are non-active light-emitting devices, with low speed, poor efficiency and low contrast. Although they can display clear text, they often produce shadows when displaying images quickly, which affects the display effect of video. , is only used in PDAs, pagers or mobile phones that require a black and white display.

Influenced by the actual number of cells in the LCD liquid crystal layer, LCD displays generally only provide a fixed display resolution. If the user needs to increase the resolution of 800X600 to 1024X768, the analog resolution can only be achieved with the help of specific software.

Like traditional CRT monitors, LCDs used in desktop systems are also designed to receive waveform analog signals rather than digital pulse signals directly generated by a PC. This is mainly because most standard graphics cards in desktop systems still convert the video information from the original digital signal to an analog signal before sending it to the monitor for display. Although the LCD of the desktop system is designed to receive analog signals, the LCD itself can only process digital information. Therefore, after receiving the analog signal from the graphics card, the LCD needs to restore the analog signal to a digital signal for processing. In order to solve the display deficiencies caused by the above problems, the latest desktop LCD adopts a special graphics card with a digital connector to transmit digital signals directly to the LCD display.

With the continuous maturity and development of LCD technology, the size of the display screen is gradually increasing. Traditional notebook computers use 8-inch (diagonal) fixed-size LCD displays, and desktop system LCDs based on TFT technology can support 14- to 18-inch display panels. Because the manufacturer determines the size of the LCD according to the size of the actual visible area, rather than the size of the picture tube like a CRT, in general, the size of a 15-inch LCD is equivalent to the size of a traditional 17-inch color display.