Liquid crystal displays include passive matrix liquid crystal display (PM-LCD) and active matrix liquid crystal display (AM-LCD). STN and TN liquid crystal display belong to passive matrix LCD. In 90s, active matrix liquid crystal display technology developed rapidly, especially thin film transistor liquid crystal display (TFT-LCD). As a replacement product of STN, it has many advantages, such as fast response and no scintillation. It is widely used in portable computer and workstations, TV, video camera and handheld video game machines. The difference between AM-LCD and PM-LCD lies in the fact that each pixel with switch devices can overcome cross interference and achieve high contrast and high resolution display. At present, AM-LCD adopts amorphous silicon (a-Si) TFT switching devices and storage capacitor schemes, which can get high gray level and achieve true color display. However, the development of P-Si (polysilicon) TFT (thin film transistor) display has been driven by the demand for high-density cameras and projection applications for high resolution and small image elements. The mobility of P-Si is 8 to 9 times higher than the mobility of a-Si. The size of P-Si TFT is small, not only suitable for high density and high resolution display, but also can be integrated into the substrate. In short, LCD is suitable for small, light and low power small and medium sized displays, which are widely used in notebook computers, mobile phones and other electronic devices. The 30 inch and 40 inch LCD have been developed and some have been put into use. LCD after scale production, the cost is decreasing. At present, the 15 inch LCD monitor has been on the market for 500 US dollars. Its future development direction is to replace the PC cathode display and its application in LCD TV.
Plasma display is a light-emitting display technology realized by the principle of gas (such as air) discharge. The plasma display has the advantage of cathode ray tube, but it is made on thin structure. At present, the mainstream product size is 4042 inches. The 5060 inch product is being developed.
Vacuum fluorescent display is widely used as a monitor for audio / video products and household appliances. It is a three pole electron tube vacuum display device, which encapsulates the cathode, the grid and the anode in the vacuum tube. It is accelerated by the positive voltage added by the grid and anode, and is stimulated by the excitation of the phosphor coated on the anode. The gate is used as a honeycomb structure.
Electroluminescent displays are made of solid state thin film technology. An insulating layer is placed between 2 conductive plates, and a thin electroluminescent layer is deposited. The device uses wide spread spectrum zinc coated plates or strontium coated plates as electroluminescent parts. The electroluminescent layer is 100 microns thick and can display as clear as an organic light emitting diode (OLED) display. Its typical driving voltage is AC voltage of 10KHz and 200V, which requires more expensive driver IC. A high resolution micro display with active array driving scheme has been developed.
The LED display consists of a large number of light-emitting diodes, which can be monochromatic or multi colored. The efficient blue LED has been on the market, making it possible to produce panchromatic large screen LED display. The LED display has the characteristics of high brightness, high efficiency and long life. It is suitable for large screen display for external use. However, using this technology can not produce a medium display for monitors or PDA. However, the LED monolithic integrated circuit can be used as a monochromatic virtual display.
This is a miniature display made of MEMS technology. In this display, the micro mechanical structure is manufactured by using standard semiconductor technology to process semiconductors and other materials. In digital micro mirror device, its structure is a micro mirror supported by hinge. The hinge is excited by the charge on the polar plate attached to one of the storage units below. The size of each micromirror is about the diameter of human hair. The device is mainly used for portable commercial projectors and home theater projectors.
The basic principle of the field emission display is the same as that of the cathode ray tube, that is, the electrons are attracted by the plates and collide with the phosphors coated on the anode. Its cathode is composed of a large number of tiny electron sources arranged in array, that is, array of one pixel and one cathode. Like a plasma display, field emission displays require high voltage to work, with a voltage range of 200V to 6000V. But so far, because of the high production cost of its manufacturing equipment, it has not become the mainstream flat panel display.
8. organic light emitting diode display
In organic light emitting diode display (OLED), current flows through 1 or more layers of plastic, which produces the phenomenon of luminescence like inorganic light-emitting diodes. This means that OLED devices require solid film stacking on the substrate. However, organic materials are very sensitive to water vapor and oxygen, so sealing is essential. OLED is an active light emitting device and exhibits excellent optical characteristics and low power consumption. They have great potential for mass production on a flexible substrate in a roll to roll process, so the manufacturing cost is very low. The technology has a wide range of applications, from simple monochromatic large area to full color video display.
The E-ink display is a display controlled by an electric field on a bistable material. It consists of a large number of micro - sealed transparent spheres, each of which is about 100 microns in diameter and contains a black liquid dyeing material and thousands of white titanium dioxide particles. When an electric field is added to the bistable material, the titanium dioxide particles migrate to one of the electrodes according to their charge state. This causes the pixels to glow or not to glow. Because the material is bistable, it can hold information for several months. Because the electric field controls its working state, it can change its display content with very little energy.