Lamp Evolution - LED

LED (Light Emitting Diode), a light emitting diode, is a solid state semiconductor device that can directly convert electricity into light. The heart of the LED is a semiconductor wafer. One end of the wafer is attached to a support, one end is negative, and the other end is connected to the positive electrode of the power supply, so that the entire wafer is encapsulated with epoxy resin. The semiconductor wafer consists of two parts, one is a P-type semiconductor, in which holes are dominant, and the other end is an N-type semiconductor, which is mainly electrons. But when these two kinds of semiconductors are connected, they form a "PN junction" between them. When the current is applied to the wafer through the wire, the electrons are pushed to the P area. In the P area, the electrons recombine with the holes, and then they emit energy in the form of photons. This is the principle of LED light emission. The wavelength of light determines the color of light, which is determined by the formation of PN junction material.

LED (Light-Emitting-Diode in Chinese) is a semiconductor that converts electrical energy into visible light. It changes the principle of the tungsten filament of an incandescent lamp and the light emission of three primary colors of an energy-saving lamp, and uses electric field emission. According to analysis, the characteristics of LED are very obvious, long life, high luminous efficiency, no radiation and low power consumption. The spectrum of the LED is almost entirely concentrated in the visible light band, and its luminous efficiency can exceed 150 lm/W (2010). Comparing the LED with ordinary incandescent lamps, spiral energy-saving lamps and T5 trichromatic fluorescent lamps, the results show that the ordinary incandescent lamp has a luminous efficiency of 12 lm/W, a life of less than 2000 hours, and a spiral energy-saving lamp with an efficiency of 60 lm/W and a lifetime of less than In 8000 hours, the T5 fluorescent lamp is 96 lm/W, and the lifetime is about 10,000 hours. The white LED with a diameter of 5 mm can have a luminous efficiency of more than 150 lm/W, and the lifetime can be more than 100,000 hours. Some people also predict that the future limit of LED life will be infinite.

High power refers to large luminous power, generally refers to 0.5W, 1W 3W 5W or higher. Light intensity and lumens are smaller than small power, but the same heat dissipation is also great, and now high power is a single application, plus a large heat sink. Low power is generally about 0.06W. LED flashlights are now generally used with low power, light scattered, depending on the LED's light angle, there are large angles and small angles of the points, small angles are scattered, large angle only scattered. Flashlights on the market are generally made with straw hats. good results. Now that some manufacturers do not re-quality, take the defective LED flashlight, will soon have dead lights.

LED brightness is a certain relationship with the LED's luminous angle, the smaller the angle of the LED, the higher the brightness, no super bright or super bright, it is deceive children, if it is a good quality LED, whichever The brightness of everyone produced by LED manufacturers is similar, but the production process is not the same, the service life is slightly different, because everyone is using those few foreign LED chips. If it is 5MM LED 180 degree angle of the white light brightness is only a few hundred MCD, if it is 15 degrees of brightness will go to the brightness of more than 10,000 20,000 MCD, the brightness difference of several dozen times, if it is used for lighting Use, in the outdoors is best to use high-power LED, the brightness is higher, a single power is 1W, 3W, 5W, there is a combination of multiple high power into a high-power LED, power goes to several hundred All have.

LED development

The development of LED display can be divided into the following stages: The first stage is from 1990 to 1995, mainly monochrome and 16-color graphic screen. It is used to display texts and simple pictures. It is mainly used in public places such as stations, financial securities, banks, and post offices as public information display tools.

The second stage was from 1995 to 1999, with 64-level, 256-level grayscale dual-color video screens. Applications such as video control technology, image processing technology, and optical fiber communication technology have brought the LED display to a new level. LED display screen control LSI chips are also developed and used by domestic companies at this time.

The third stage began in 1999. A large number of red, green, and blue LED tubes flooded into China. At the same time, domestic companies conducted in-depth research and development. Full-color displays using red, green, and blue primary LEDs were widely used. Massive access to sports venues, convention centers, plazas and other public places will bring the domestic large screen into the full-color era.

With the rapid development of LED raw material market, surface mount devices have been available since 2001. They are mainly used in indoor full-color screens, and with their high brightness, vivid colors, and low temperature characteristics, the dot pitches that can be adjusted freely are demanded by different price points. It was accepted that in just over two years, the sales volume of the product has exceeded 300 million yuan, and the surface mount full-color LED display application market has entered the new century. In order to adapt to the “slimming” plan of the 2008 Olympic Games, Ryad developed a surface-mount dual-color display screen, which is widely used in training halls and competition timing scoring systems. In the full color screen of Olympic venues, for the purpose of tightening investment, most of the full-color screens are detachable. During the Olympics, they can be used as live broadcasting tools. After the end of the competition, they can be used for leasing, as public utilities such as performances and national policy announcements. The method can recover the cost as soon as possible.

In terms of the market, China's accession to the WTO, Beijing's successful bid for the Olympics, etc., have become new opportunities for the development of the LED display industry. The domestic LED display market continues to grow. Currently, in the domestic market, the domestic LED display market share is nearly 95%. International LED display market capacity is expected to increase at a rate of 30% per year.

The main manufacturers of LED display screens are concentrated in Japan, North America and other places, and the export share of China's LED manufacturers is insignificant. According to incomplete statistics, there are currently at least 150 manufacturers in the world producing full-color screens, of which about 30 are full-scale companies.

At present, after the Chinese government actively promotes the LED industrialization, the domestic LED display production technology is basically synchronized with the world. The domestic well-known brands are: Apex Kolor, Yuanliang International Lighting, Hengyu Optoelectronics, and Big Eyes Optoelectronics. (TopVision), yaham, skymax-display, Lightking, Unilumin, Retop, aled, liantronics ), cfled, MejLed, dicolor, lenson, lhgd, TOP, Shilan, Yachiguang (Art) ), Jin Lixiang, Absen, Aswei, ledsun, Leidard, SBC, Sansi, Optoelectronics, etc.

LED application

In view of the LED's own advantages, it is mainly used in the following major areas:

(1) Application of display screen and communication number display light source The LED lamp has the characteristics of shock resistance, fast light response, long life, and long service life. It is widely used in various indoor and outdoor displays and is divided into full-color and three-color. And monochrome display, a total of more than 100 units across the country in the development and production. Traffic lights mainly use ultra-high-brightness red, green and yellow LEDs. Since LED lights are both energy-efficient and highly reliable, traffic lights are gradually being upgraded nationwide, and the speed of promotion is high. The market demand is large. It is a good market opportunity.

(2) Applications in the automotive industry Automotive lights include dashboards, audio indicators, backlights for switches, reading lights, and external brake lights, tail lights, side lights, and headlights. Incandescent lamps used in automobiles are not resistant to shock, are easily damaged, and have a short life span. They need to be replaced frequently. In 1987, China began to install high-level brake lights on cars. Due to the fast response of the LED, it is possible to promptly warn the driver of the brakes and reduce rear-end collisions. In developed countries, the use of LED central rear high-level brake lights has become a standard part of the car.

The LED automotive taillight modules introduced by semiconductor lighting can be freely combined into various automotive taillights. In addition, ultra-high-brightness light sources can be used as light sources in automobile dashboards and various other lighting sections, so LED displays are gradually adopted. China's auto industry is in a period of great development and is an excellent opportunity to promote ultra-high brightness LEDs. In recent years, an annual output value of 1 billion yuan will be formed, and an output value of 3 billion yuan will be formed in 5 years.

(3) LED Backlight The backlight with high efficiency side emission is the most attractive. LED, as an LCD backlight source, has long life, high luminous efficiency, no interference and high cost performance. It has been widely used in electronic watches, mobile phones, and BP. With the increasing miniaturization of portable electronic products, LED backlights have advantages in machines, electronic calculators, and credit card machines. Therefore, backlight source manufacturing technologies will develop toward thinner, lower power consumption and uniformity. LED is the key device of the mobile phone, an ordinary mobile phone or PHS needs to use 10 LED devices, and a color screen and mobile phone with camera function need to use about 20 LED devices. At this stage, the amount of mobile phone backlights is very large, and 3.5 billion LED chips will be used in one year. At present, China's mobile phone production is very large, and most of the LED backlight source is still imported. For domestic LED products, this is an excellent market opportunity.

(4) Early LED lighting products have low luminous efficiency, and the light intensity can only reach several to several tens of mcd. It is suitable for indoor applications, such as home appliances, instrumentation, communication equipment, computers and toys. The current goal is to replace incandescent and fluorescent lamps with LED light sources, and this alternative trend has begun to develop from local applications. In order to save energy, Japan is planning to replace incandescent light-emitting diode projects (called "lighting Japan"), with a budget of 5 billion yen for the first five years. If LED replaces half of the incandescent and fluorescent lamps, the annual savings will be equivalent. The energy of 6 billion liters of crude oil, equivalent to the power of five 1.35×106kW nuclear power plants, can reduce the production of carbon dioxide and other greenhouse gases and improve the living environment of people. China also invested 5 billion yuan in 2004 to develop an energy-saving and environmentally friendly semiconductor lighting program.

(5) other applications such as a kind of flash shoes that are popular among children, the built-in LED will flash when walking, only 500 million light-emitting diodes will be used in Wenzhou every year; the use of light-emitting diodes as the power indicator of the electric toothbrush, according to domestic Manufacturers in production introduction, the company has a small amount of health toothbrush listed, is expected to require 300 million light bulbs per year in mass production; LED Christmas lights are popular, due to novelty, rich colors, not broken and low-voltage safety Sex, the recent strong sales in Hong Kong and other Southeast Asian regions, has been widely welcomed and is threatening and replacing the existing bubble Christmas market.

(6) LED products for home interior lighting are more popular, LED downlights, LED ceiling lights, LED fluorescent lamps, LED fiber optic lights have quietly entered the family!