Because its yellow light is too dark, it is not suitable for practical application; What is more difficult is that silicon carbide and electroluminescence are not well adapted.
The research was abandoned. Bernhard Gooden and Robert Wichard used zinc sulfide and zinc sulfide in Germany in the late 1920s.
Yellow phosphorus extracted from copper will glow. Once again, it stopped because of dim light. 1936, George Destiau published a report on the luminescence of zinc sulfide powder. With the application and wide understanding of current, it finally appeared.
The term "electroluminescence" was introduced. In 1950s, British scientists used semiconductors in electroluminescent experiments.
Gallium arsenide invented the first modern LED, which appeared in the 1960s. It is said that in early experiments, LED needs
In liquid nitrogen, further operation and breakthrough are needed to work efficiently at room temperature. The first commercial LED could only emit invisible infrared light, but it was quickly applied in the fields of induction and photoelectricity. In the late 1960s, in gallium arsenide,
The first visible red LED was invented by using phosphide on the substrate. The change of gallium phosphide makes LED more efficient and emit red light.
Brighter and even produce orange light. By the mid-1970s, gallium phosphide was used as a light source, and then it emitted ashes.
White light and green light. LED adopts double-layer gallium phosphide chip (one red and one green), which can emit yellow light. Just then,
Russian scientists use emery to make yellow LEDs. Although not as efficient as European LEDs. But in the late 1970s,
It can emit pure green light. 1The use of gallium arsenide and aluminum phosphide in the early and middle 1980s made the first generation of high-brightness light-emitting diodes.
Born, first red, then yellow, and finally green. By the early 1990s, indium, aluminum, gallium and phosphorus were used in production.
There are orange, orange, yellow and green LEDs. The first historic blue LED also appeared in the early 1990s.
The second utilization of diamond sand-the obstacle of early semiconductor light source. According to today's technical standards, it is almost the same as the yellow in Russia.
The light is as dim as an LED. In the mid-1990 s, ultra-bright GaN LED appeared and was later manufactured to produce high intensity.
Green and blue InGaN LEDs. Ultra-bright blue chip is the core of white LED, which is coated with fluorescence.
Phosphorus, and then fluorescent phosphorus is converted into white light by the blue light source of the absorption core. Is to use this technology to make any.
What color of light is visible. Today, you can see the novel colors produced in the LED market, such as light green and pink. have
Readers of scientific thoughts may realize that the development of LED has gone through a long and tortuous historical process. in fact
The recently developed LED can not only emit pure ultraviolet light, but also emit real "black" ultraviolet light. Then lead the development.
I wonder how stupid history has become. Maybe one day we can develop an LED that can emit X-rays. However, the development of LED not only
It's just its color and its brightness. Like computers, it follows the development of Moore's Law. Every 18 months, its brightness is
Will double. Early LEDs can only be used in indicator lights, early calculator display screens and digital watches. From now on,
Appears in the ultra-bright field. Will continue for some time to come. For example, by 2005, all traffic letters in the United States
No. The indicator light will be replaced by LED; The American automobile industry will also stop using incandescent lamps and adopt LED lamps within ten years, including car headlights. Most large outdoor display screens also use thousands of LEDs to produce high-quality video effects.
Soon, LED will light up our homes, offices and even streets. Efficient and energy-saving LEDs mean that solar rechargeable batteries can
Charge it with sunlight. So that the light source can be brought to the third world and other places without electricity. Once dim
Light-emitting diodes now truly herald the arrival of a new era of LED.
Development prospect of LED industry:
With the further increase of global LED market demand, China LED industry will face great opportunities in the future. However, at present, LED core technologies and patents are basically monopolized by foreign countries, and domestic enterprises are "painfully" moving forward in "happiness"-
In 2008, at the opening ceremony of the Beijing Olympic Games, the magical "scroll" color screen came from China Jinlixiang Technology Co., Ltd.
In 2009, the 60th anniversary of the National Day military parade, the huge color screen on Tiananmen Square came from China Liard Electronic Technology Co., Ltd.;
In 20 10, at the opening ceremony of Shanghai World Expo, 10000 square meter large-screen semiconductor light-emitting diode (hereinafter referred to as led) came from China Ruituo Display Technology Co., Ltd. ...
Behind these seemingly endless enterprises, there are huge hidden dangers in the development of LED industry in China. The reporter found that at present, more than half of the technologies and patents in the global LED field are occupied by a few large companies in developed countries such as the United States, Japan and Germany. Most of these patents are core technology patents, and it is difficult for domestic enterprises, especially small and medium-sized enterprises, to find a breakthrough. In addition, these foreign companies have carefully laid out their patent networks around the world, especially in China, just like a sword of Damocles hanging over their heads. If the LED industry in China wants to achieve long-term development, it must break through the layers of these patents.
condition
Rapid development, but the enterprise scale is small and the industrial chain is incomplete.
As the most attractive new generation light source in the world, LED is known as the most promising green lighting source in 2 1 century with its advantages of high brightness, low heat, long life, non-toxicity and recyclability. The LED industry in China began in 1970s. After nearly 40 years of development, it has formed seven national semiconductor lighting engineering industrialization bases in Shanghai, Dalian, Nanchang, Xiamen, Shenzhen, Yangzhou and Shijiazhuang, and its products are widely used in landscape lighting and general lighting. China has become the world's largest producer and second largest exporter of lighting appliances.
However, a statistical data of LED industry research institute-China LEDinside shows that by the end of 2009, there were more than 3,000 LED enterprises in China, of which only 140 had an annual output value of over 100 million. However, among these 140 enterprises, none of them has annual sales of products exceeding 1 100 million yuan, and only a few of them exceed 500 million yuan, mostly between 1 100 million yuan and 200 million yuan. It can be seen that although there are many LED enterprises in China, the scale is generally small.
The reporter randomly selected a domestic LED company for interview. Guangdong Dongguan Qinshang Optoelectronics Co., Ltd. (hereinafter referred to as Qinshang Optoelectronics) was established in 1993. Is an early enterprise engaged in the production of LED products in China, and jointly established the LED Lighting Technology Research Institute with Tsinghua University. Many domestic projects, such as lighting for the National Grand Theatre, road lighting for Beijing Green Olympics, lighting for Shanghai F 1 circuit, lighting for Tsinghua University Olympic venues, etc., come from this enterprise. However, it is such a "pathfinder" for the development of domestic LED industry. In the face of the patent "containment" of Japan and the United States, it had to detour to avoid it.
"The R&D of Qinshang Optoelectronics is mainly concentrated in the downstream application field, and the R&D investment in the upper and middle reaches is relatively small. This is mainly because large foreign companies and some enterprises in Taiwan Province Province monopolize most of the LED core technologies, and domestic enterprises can only turn their attention to the downstream application market with low technology content. " Wan Wei, Intellectual Property Commissioner of Qinshang Optoelectronics, was outspoken about the current situation of domestic LED enterprises when interviewed by China Intellectual Property News.
According to the reporter's understanding, at present, the world has initially formed an industrial structure with Asia, North America and Europe as the center, Niya Chemical and Toyota Synthesis in Japan, Kerry, General Electric and Osram in Germany as the patent core. American and Japanese companies have monopoly advantages in epitaxial wafer and chip technology and equipment, while European companies have outstanding advantages in the field of applied technology, while China's LED is still at a low level. About 80% of the products are concentrated in the application markets such as landscape lighting and traffic lights, and less high-end products such as automobile lighting and large screens are involved.
Abdominal mass
Lack of core patents, Industry-University-Research's cooperation is loose.
"The five major international manufacturers from Japan, the United States and Europe represent the highest level of LED today and have a significant impact on industrial development. This influence is not only reflected in products and income, but more importantly, the monopoly of technology. More than 50% of the core patents are in the hands of these five major manufacturers. " An industry analyst introduced to our reporter.
With the rapid development of domestic LED market, more and more foreign enterprises are looking to China. Especially in recent years, the number of patent applications in LED field accepted by China has increased significantly year by year. According to a risk analysis report of semiconductor lighting patent provided by China National Intellectual Property Administration Development Research Center, by the end of 2008, 22 countries and regions around the world had applied for patents in China, and countries with obvious technological advantages applied for patents in China. The top five countries are Japan, South Korea, the United States, Germany and the Netherlands. Among them, Japan is far ahead with 1306 patent applications, accounting for 24% of the total number of applications, and the other four countries account for 7%, 5%, 4% and 3% of the total number of applications respectively.
In terms of effective patents, the ratio of domestic patent applications to foreign patent applications in China is about 4 to 5. However, in these domestic patent applications, Taiwan Province Province occupies a large share, and its effective invention patents account for 53%. In other words, if Taiwan Province Province is excluded, the gap between Chinese mainland and foreign countries in the number and gold content of patents will be even greater.
In addition, from the perspective of industrial chain distribution, foreign companies mainly have more patent layouts in the fields of chips and packaging, and half of LED core inventions have filed patent applications in China. Niya Chemical, Osram, Ramide, Kerry, General Electric and other companies have mastered most of the core patented technologies. Among them, Riya Chemical has the most core patents, involving all industrial chains except packaging.
Compared with the above foreign companies, China's LED patent application is obviously at a disadvantage. According to the survey of the LED Industry Research Institute of Hi-Tech, by the end of 2008, the number of LED-related patent applications in China was 2607 1 10,000, of which the middle and lower reaches of the industry were close to 50%. Although China has certain advantages in electrode, microstructure, reflective layer and substrate peeling/bonding, most of them belong to peripheral patents, with invention patents accounting for only 60%. There are few international patent applications and foreign patents submitted through Patent Cooperation Treaty (PCT).
It is understood that China's LED industry is not competitive in core technology, and the loose combination of Industry-University-Research is also the main factor restricting its development. A large part of LED patents in China are concentrated in scientific research institutes. For example, in the field of extension, the top three patents are Institute of Semiconductors, Institute of Physics of Chinese Academy of Sciences and Beijing University of Technology. In the field of chips, the top three are Semiconductor Institute of Chinese Academy of Sciences, Beijing University of Technology and Peking University. Compared with scientific research institutions, domestic enterprises apply for more utility model patents.
Lack of core patents and loose cooperation in Industry-University-Research have become a sword of Damocles hanging over Chinese enterprises, which is followed by the risk of patent infringement faced by enterprises at any time.
"In February 2008, an old American woman filed an application with the US International Trade Commission on the grounds of patent infringement, requesting 337 investigations on 34 companies including Hitachi, Samsung and Toshiba, including six China companies including Guangzhou Lihong Optoelectronics Co., Ltd. and Shenzhen Zhou Lei Electronics Co., Ltd. This case sounded the alarm for the led industry in China." An industry expert told reporters that with the further expansion of the LED market, China enterprises will face higher and higher patent risks.
Countermeasures
Strengthen independent research and development and attach importance to the important role of patents.
The concentrated display of LED lighting in Beijing Olympic Games, Shanghai World Expo and other major events has given people a brand-new understanding and effectively promoted the development of LED industry in China. But for domestic enterprises, strengthening independent research and development, expanding scale and improving product quality and technical level are the primary tasks at this stage.
Wang Huajun, director of the patent development and licensing department of the Intellectual Property Center of TCL Group Co., Ltd., told the reporter: "Faced with the' eyeing' of foreign companies, domestic enterprises should practice their' internal strength', increase the intensity of independent innovation, focus on developing new technologies that can be widely accepted and recognized by the market, and start licensing and cooperation with foreign companies on this basis."
In addition, "on the basis of digesting and absorbing foreign advanced technology, strengthening imitation and innovation, improving the technical effect of competitors' core patents and applying for patent improvement are effective ways to avoid the risk of patent infringement. Mao Jinsheng, director of China National Intellectual Property Administration Development Research Center, pointed out.
In this regard, Xie, a lawyer of Beijing Cube Law Firm, also expressed the same view. He believes that enterprises should learn to use advanced technology legally, track patents that are about to expire, sign patent licensing contracts, anti-monopoly licenses, cross-licensing, and authorize production, and open up markets in countries where patents are not covered.
As domestic enterprises are facing more and more intellectual property disputes, especially foreign-related patent lawsuits, Wang Huajun suggested: "When enterprises receive patent infringement lawsuits from multinational companies, it is the best policy to choose to actively respond, and learn to skillfully use different patent systems and legal proceedings in different countries." He further explained that taking the United States as an example, using the evidence exchange procedure in American civil litigation, domestic enterprises can ask the plaintiff to provide all technical information related to the patent involved, including technical secrets.
In addition, strengthening the cooperation between enterprises and research institutions in Industry-University-Research is also an effective way to promote the rapid development of China's LED industry. Mao Jinsheng said that some domestic research institutions have certain R&D capabilities, while some enterprises have strong processing and manufacturing capabilities. Enterprises, enterprises and scientific research institutions should strengthen their sense of cooperation, promote the transfer of innovation achievements of scientific research institutions to enterprises, and strive to cultivate a number of innovative "leading" enterprises with independent intellectual property rights.
During the interview, the reporter learned that although there are some problems in the development of China's LED industry, it is undeniable that this situation has gradually improved. Moreover, China's advantages in some fields, such as substrate, epitaxy, packaging and chip, cannot be ignored. Some research institutes have world-leading patented technologies and have the ability and strength to compete with multinational companies.
Faye Ting, director of the itei Industrial Safety Research Center, told reporters that the concept of LED enterprises in China is gradually changing. More and more small and medium-sized enterprises begin to make strategic arrangements, gradually attach importance to the early accumulation of intellectual property rights, learn to arm themselves with science and technology, and use patents to open up domestic and foreign markets, turning "traps" into good market prospects. "With a good experimental field and breakthrough direction, enterprises should sum up more experiences and lessons in order to fly higher and farther."
Background link
What is an LED?
LED(LightEmittingDiode), which means light emitting diode in Chinese, is a solid semiconductor device that can convert electric energy into visible light, and can directly convert electricity into light. It has the characteristics of small volume, low power consumption, long life, high brightness, low heat generation, environmental protection and durability. Mainly used in various indoor and outdoor display screens, dashboards, brake lights, taillights, electronic watches, mobile phones and so on.
What parts does the LED industry chain include?
The LED industrial chain mainly includes four parts: LED epitaxial wafer, LED chip manufacturing, LED device packaging and product application, as well as related supporting industries.
Generally speaking, epitaxy belongs to the upstream of the LED industry chain, chips belong to the midstream, and packaging and application belong to the downstream. The upstream is a capital and technology-intensive field, and the entry threshold of the middle and lower reaches is relatively low.
What is an LED epitaxial wafer?
The basic principle of LED epitaxial wafer growth is: on the substrate heated to a proper temperature, mainly sapphire, sic and Si, gaseous substances InGaAlP are transported to the surface of the substrate in a controllable way to grow a specific single crystal film. At present, the growth technology of LED epitaxial wafer mainly adopts organometallic chemical vapor deposition.
The substrate material of LED epitaxial wafer is the cornerstone of the technical development of semiconductor lighting industry. Different substrate materials need different LED epitaxial wafer growth technology, chip processing technology and device packaging technology, and the substrate material determines the development route of semiconductor lighting technology.
At present, there are only two kinds of substrates that can be used for commercialization, namely sapphire and silicon carbide. Other substrates, such as GaN, Si and ZnO, are still in the research and development stage, and there is still a long way to go before industrialization.
What is an LED chip?
LED chip, also known as LED luminous chip, is a solid-state semiconductor device. Its main function is to convert electric energy into light energy. The main material of the chip is monocrystalline silicon.
The semiconductor wafer consists of two parts, one is a P-type semiconductor, in which holes are dominant, and the other is an N-type semiconductor, mainly electrons. But when these two semiconductors are connected together, a pn junction is formed between them. When the current acts on the chip through the wire, the electrons will be pushed to the P region, where they will recombine with holes and then release energy in the form of photons, which is the principle of LED light emission. The wavelength of light, that is, the color of light, is determined by the material forming the pn junction.
What is LED package?
LED packaging refers to the packaging of light-emitting chips, which is quite different from integrated circuit packaging. It requires not only to protect the wick, but also to be able to transmit light. Therefore, LED packaging has special requirements for packaging materials.
LED packaging technology is mostly developed on the basis of discrete device packaging technology, but it has great particularity. Generally speaking, the die of a discrete device is sealed in a package, and the main function of the package is to protect the die and complete the electrical interconnection. LED packaging is the function of outputting electrical signals, protecting the normal operation of the die and outputting visible light, which has both electrical and optical parameters, so it is impossible to simply package LEDs with discrete devices.
LED package includes pin package, surface mount package, power package and other forms.
What are the LED application products?
Information display. Information display, digital display of electronic instruments, equipment, household appliances, etc. Information display, advertisements, scoreboards, etc. of various displays and LED display screens.
Traffic lights. Signal lights for urban traffic, highways, railways, airports, navigation and inland navigation.
Car lights. Interior and exterior lights, turn signals, brake lights, fog lights, headlights, instrument displays and automobile lighting.
LED backlight. Small backlight: less than 10 inch, mainly used for mobile phones, MP3, MP4, PDA, digital cameras, video cameras and fitness equipment; Medium backlight: 10 inch to 20 inch, mainly used for notebook computers, computer monitors and various monitors; Large-size backlight: larger than 20 inches, mainly used for color TV display screen.