What is a Flat Panel Display (FPD)

Flat Panel Display (FPD)

Flat Panel Display (FPD)

FPD (Flat Panel Display), as the name suggests, is a TV with a flat screen. It is a type of TV compared to the bulky traditional cathode ray tube TVs. It mainly includes several major technical types of TV products, including liquid crystal display LCD (Liquid Crystal Display), plasma display PDP (Plasma Display Panel), organic light luminescent display OLED (Organic Light Emitting Display), and surface-conduction electron-emitter display SED (Surface-conduction Electron-emitter Display).

Development Trend of Flat Panel Displays (FPD)

Compared with traditional CRT (cathode ray tube), flat panel display has the advantages of thinness, lightness, low power consumption, low radiation, no flicker, and good for human health. At present, it has surpassed CRT in global sales. It is expected that by 2010, the sales value ratio of the two will reach 5:1. In the 21st century, flat panel display will become the mainstream product in display. According to the famous Stanford Resources company, the global flat panel display market will increase from 23 billion US dollars in 2001 to 58.7 billion US dollars in 2006, and the average annual growth rate will reach 20% in the next four years.

Flat panel display technologies have their own advantages

Flat panel displays are divided into active light-emitting displays and passive light-emitting displays. The former refers to display devices that provide visible radiation by emitting light from the display medium itself, including plasma display panels (PDP), vacuum fluorescent displays (VFD), field emission displays (FED), electroluminescent displays (LED) and organic light-emitting diode displays (OLED). The latter refers to devices that do not emit light themselves, but use the display medium to be modulated by electrical signals, and its optical properties change, to modulate the light emitted by ambient light and external power sources (backlight sources, projection light sources), and display on the display screen or screen. It includes liquid crystal displays (LCD), micro-electromechanical system displays (DMD) and electronic ink (EL) displays.

1. Liquid Crystal Display (LCD)

Liquid crystal displays include passive matrix liquid crystal displays (PM-LCD) and active matrix liquid crystal displays (AM-LCD). Both STN and TN liquid crystal displays belong to passive matrix liquid crystal displays. In the 1990s, active matrix liquid crystal display technology has achieved rapid development, especially thin film transistor liquid crystal displays (TFT-LCD). As a successor to STN, it has the advantages of fast response speed and no flicker, and is widely used in products such as portable computers and workstations, televisions, camcorders and handheld video game consoles. The difference between AM-LCD and PM-LCD is that the former has a switching device added to each pixel, which can overcome cross-interference and obtain high contrast and high resolution display. The current AM-LCD uses amorphous silicon (a-Si) TFT switching device and storage capacitor solution to obtain high grayscale and achieve true color display. However, the demand for high resolution and small pixels in high-density cameras and projection applications has promoted the development of P-Si (polycrystalline silicon) TFT (thin film transistor) displays. The mobility of P-Si is 8 to 9 times higher than that of a-Si. P-Si TFT is small in size and is not only suitable for high-density and high-resolution displays, but also peripheral circuits can be integrated onto the substrate.

In short, LCD is suitable for small and medium-sized displays that are thin, light, and consume little power. They are widely used in electronic devices such as laptops and mobile phones. 30-inch and 40-inch LCDs have been successfully developed, and some have been put into use. LCDs are being mass-produced, and their costs are constantly decreasing. Currently, a 15-inch LCD monitor priced at $500 is available on the market. Its future development direction is to replace the cathode display of PCs and be used in LCD TVs.

2. Plasma display panel (PDP)

Plasma display is a light-emitting display technology that uses the principle of gas (such as nitrogen) discharge. Plasma display has the advantages of cathode ray tubes, but is manufactured on a very thin structure. Currently, the mainstream product size is 40-42 inches. 50-60-inch products are under development.

3. Vacuum Fluorescent Display (VFD)

Vacuum fluorescent display is a kind of display widely used in audio/video products and household appliances. It is a triode electron tube type vacuum display device that encapsulates the cathode, grid and anode in a vacuum tube shell. The electrons emitted by the cathode are accelerated by the positive voltage applied by the grid and anode, and stimulate the phosphor coated on the anode to emit light. Its grid adopts a honeycomb structure.

4. Electroluminescent Display (ELD)

Electroluminescent displays are made using solid-state thin film technology. An insulating layer is placed between two conductive plates, and a thin electroluminescent layer is deposited. The device uses a zinc-coated plate or a strontium-coated plate with a wide emission spectrum as the electroluminescent component. Its electroluminescent layer is 100 microns thick and can achieve a display effect as clear as an organic light-emitting diode (OLED) display. Its typical driving voltage is 10KHz, 200V AC voltage, so it requires a more expensive driver integrated circuit. High-resolution micro displays using active array drive schemes have been successfully developed.

5. Light Emitting Diode Display (LED)

LED displays are made up of a large number of light-emitting diodes and can be monochrome or multi-color. High-efficiency blue LEDs are now available, making it possible to produce full-color large-screen LED displays. LED displays have the characteristics of high brightness, high efficiency and long life, making them suitable for large-screen displays for outdoor use. However, this technology cannot be used to produce medium-sized displays for monitors or PDAs (palmtop computers). However, LED monolithic integrated circuits can be used as monochrome virtual displays.

6. Micro-electromechanical system display (DMD)

This is a micro display made using MEMS technology. In this display, the tiny mechanical structure is made by processing semiconductors and other materials using standard semiconductor processes. In the DMD, the structure is a micro mirror supported by a hinge. The hinge is activated by the charge on the plate connected to a storage cell below. Each micro mirror is about the diameter of a human hair. The device is mainly used in portable business projectors and home theater projectors.

7. Field Emission Display (FED)

The basic principle of field emission display is the same as that of cathode ray tube, that is, the plate attracts electrons and makes them collide with the phosphor coated on the anode to emit light. Its cathode is composed of a large number of fine electron sources arranged in an array, that is, arranged in an array form of one cathode per pixel. Like plasma display, field emission display requires high voltage to work, and its voltage range is 200V to 6000V. However, so far, due to the high production cost of its manufacturing equipment, it has not become a mainstream flat panel display.

8. Organic Light Emitting Diode Display

In an organic light-emitting diode display (OLED), an electric current is passed through one or more layers of plastic, which produces the same phenomenon as that of an inorganic light-emitting diode. This means that what is required for an OLED device is a solid-state film stack on a substrate. However, organic materials are very sensitive to water vapor and oxygen, so sealing is essential. OLEDs are active light-emitting devices and show excellent light characteristics and low power consumption. They have great potential for mass production in a roll-to-roll process on a flexible substrate, so their manufacturing cost is very low. The technology has a wide range of applications, from simple single-color large-area lighting to full-color video graphics displays.

9. Electronic ink display (E-ink)

E-ink display is a display controlled by applying an electric field to a bistable material. It is composed of a large number of micro-sealed transparent spheres, each of which is about 100 microns in diameter and contains black liquid dye material and thousands of white titanium dioxide particles. When an electric field is applied to the bistable material, the titanium dioxide particles will migrate to one of the electrodes according to their charge state. This causes the pixel to emit light or not. Since this material is bistable, it can store information for up to several months. Since its working state is controlled by an electric field, the displayed content can be changed with very little energy.

Each technology of LCD, PDP and OLED
for manufacturing flat panel displays has its own advantages and disadvantages (see Table 1). However, LCD will still dominate the future flat panel display market. In the next few years, the market share of LCD, which currently accounts for 90% of the flat panel display market, will gradually decrease. However, as a general-purpose display, it is the only one. In addition, the development prospects of LCD and OLED are also very promising. These three will dominate the future flat panel display market.