Where LED lighting technology comes from

LED lighting technology is the first breakthrough in Japan in 1993 and in 1996 to achieve white LED, after several years of development, the global semiconductor lighting industry has formed a three-legged industrial distribution and competition pattern dominated by the United States, Asia and Europe. The United States Cree, Lumileds, Japan Nichia, Toyodagosei, Germany OSRAM and other monopoly high-end product market.

LED (lightingemittingdiode) lighting is light-emitting diode lighting, which is a semiconductor solid-state light-emitting device. It uses solid-state semiconductor chips as light-emitting materials, and in semiconductors, excess energy is emitted through the recombination of carriers to cause photon emission, which directly emits red, yellow, blue, green, cyan, orange, violet, and white light. LED lighting products are lighting appliances made by using LED as a light source.

Brother, your question is really a bit big.

I have no choice but to elaborate briefly, and then be specific when there are specific issues.

The entire LED industry chain includes four major fields: upstream, midstream, downstream and application, and lighting belongs to the category of application.

The core of LED lighting technology is mainly about which occasions you use LED and how to control it.

To be more specific, it is the power supply that powers the LED, also called the driver, and the system that controls its dimming or color change.

This technology originates from the early switching power supply technology and intelligent control technology (program control).

LED chips.

The chip substrate determines the epitaxial material and the subsequent process, and the more mature ones currently used are sapphire substrate, silicon carbide substrate and silicon substrate. Silicon carbide substrate is the patent of the American Cree company, and the use of sapphire substrate is more popular, but the equipment process is also in the hands of foreign businessmen. Only silicon substrate LEDs have their own intellectual property rights in China, and currently have R&D and production in Nanchang, but they can only be mass-produced on the scale of small-size chips.

LED lamp beads or module package.

Mainly production equipment and thermally conductive materials. All kinds of dispensing, die bonding, wire bonding, perfusion, sorting equipment; Thermally conductive glue, silver paste, phosphor, encapsulating material, etc. are imported from abroad, and are gradually being imitated and improved in China.

LED lamp assembly.

The LED downstream industry belongs to the semi-traditional technology field, which is suitable for China's development; Switching power supply, LED driver IC and aluminum alloy die-casting technology are the focus. These are developed by the private sector themselves, and policy support is sufficient.

The research and development of upstream, midstream and downstream application materials for LEDs, such as high thermal conductivity aluminum substrates, ceramic heat dissipation materials, and chip substrates with high thermal conductivity and low expansion coefficient, has considerable room for development in China. These materials help high-power LEDs improve chip size and luminous efficiency. At present, the state does not pay enough attention to this aspect, and it is worth reviewing the large amount of subsidy for the import of MOCVD production equipment.

These R&D do not require a large investment, but the first period is long, and the state should take the initiative to designate academic institutions to cooperate with relevant industries to develop and give greater incentives.

Light-emitting diodes are abbreviated as LEDs. It is made of compounds containing gallium (Ga), arsenic (As), phosphorus (P), nitrogen (N), etc. The use is also used as an indicator light, display board, etc.; With the continuous advancement of technology, light-emitting diodes have been widely used in displays, TV lighting, decoration and lighting.

In the more than 10 years before the advent of LED in the 60s of the 20th century to the 80s, LED only has red, yellow, and green colors, and the luminous efficiency is very low (only about 1 lm w), the brightness is relatively low, and the highest is high, and people just use it as an indicator light for electronic products. From the perspective of LED development and application history, this period is the indication application stage of LED.

1. AC power indicator;

As long as the circuit is connected to a 220V 50Hz AC power supply line, the LED will be lit up to indicate that the power is on. The current limiting resistor R has a resistance value of 220V IF.

2. AC switch indicator;

When the switch is disconnected and the bulb is turned off, the current forms a loop through R, LED and bulb, and the LED is bright, which is convenient for people to find the switch in the dark. At this time, the current curving in the loop is very small, and the bulb will not light up. When the switch is turned on, the bulb is lit and the LED is off.

3. AC power socket indicator;

A two-color (common cathode) LED is used as an AC power socket indicator circuit. The power supply of the socket is controlled by the switches. When the red LED is on, the socket has no power; When the green LED is on, the socket has power.

4. Fuse tube holder indicator;

LEDs are used as circuits for the fuse holder indicator of the distribution box of factory equipment. When the fuse tube is intact, the LED does not light up; When the fuse is blown out, the LED will light up to indicate to the user which fuse has been blown so that it can be replaced. This is very convenient for porcelain-core fuses that cannot be observed with the naked eye.

5. LED advertising signboard lights;

6. LED monochrome or color display;

Generally, the monochrome display is used to display single-line Chinese characters, and the color display is used for outdoor large-screen TVs.

7. LED street lamp;

8. LED car signal lights and LED electric vehicle lights;

The earliest practical electric lamp was the incandescent lamp, but long before the birth of the incandescent lamp, the Englishman Humphrey David used 2000 batteries and two carbon rods to make the arc lamp, but the arc lamp was too bright, produced too much heat and was not durable, and it could not be used in ordinary places.

In 1955, Rubin Braunstein of the Radio Corporation of America discovered the infrared radiation of gallium arsenide (GaAs) and other semiconductor alloys, and in 1962, Nick Holonyak JR of the General Electric Company (GE) of the United States developed visible LEDs.

In 1955, Rubin Braunstein of the Radio Corporation of America discovered the infrared radiation of gallium arsenide (Gaas) and other semiconductor alloys, and in 1962, Nick Holonyak JR of the General Electric Company of the United States developed a visible LED. However, the real take-off of LED was in the 1990s at Nichia Chemical Industries Ltd. in JapanIn 1994 and 1995, Shuji Nakamura made major breakthroughs in gallium nitride (GaN) research and obtained blue LEDs, which officially launched the era of wide range of LED applications after the breakthrough in blue LED technology.

Shuji Nakamura, born on May 22, 1954 in Ikata Town, Japan, graduated from Tokushima University, Japan, a Japanese-American electrical engineer, and a professor in the Department of Materials at the School of Engineering at the University of California, Santa Barbara.

In 1993, while working at Nichia Corporation in Japan, Shuji Nakamura became widely known for developing high-brightness blue LEDs based on GAN. At the time, it was considered impossible to develop a blue LED, and for the previous 20 years there were only red and green LEDs.

On October 7, 2014, Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura were awarded the 2014 Nobel Prize in Physics for their invention of the "high-efficiency blue light-emitting diode".

The application of LED light source, in terms of projectors, the main significance is to open up a new way for the miniaturization of the fuselage. Due to the small size of the LED light source and the advantages of many display technologies, it is more suitable for the development of small projectors and even originals, so that the user's projection is more "portable" and "free".

LEDs are used for projection lighting, which not only increases the lifespan, but also changes the projector structure, due to the reduced heat dissipation demand, and the shortening of the optical path system, so the heat dissipation and noise have better performance.

At present, the LED light source is mainly used in two kinds of projection products, the integrated small projection element and the pocket small computer, the integrated small projection element is not made into an independent model, which is mainly integrated with micro display devices such as mobile phones, digital cameras, notebook computers, battery power, can project about A4 paper or standard letter paper size of the image, convenient to share the picture with others.

The pocket-sized handheld projector is a complete stand-alone model, small and lightweight, easy to pick up with one hand, easy to carry, can be placed in a file bag, and the future development direction is business applications. It can be used for both AC and DC, the projection screen can be larger than 17 inches, the screen brightness is 15 to 200 lumens, and with the development of technology, the display effect is still improving.

The relationship between the intensity and the distance to the light source is inversely proportional to the square. The inverse square consciousness is that if point B is twice as far away from the light source as point A, then the intensity of the light received by point B is one-fourth of that of point A.

According to the relationship between the light source and the object, the position of the light source can be divided into four basic types of lighting, including natural lighting and artificial lighting.

Small efficacy, small size, long life, easy to drive, environmental protection and so on.