LED is the abbreviation of Light Emitting Diode (LED), also known as Light Emitting Diode. Since the development of this semiconductor component, it is generally used as indicator light and display board, but with the increase of technology, it can be used as a light source. , It not only can directly convert electrical energy into light energy with high efficiency, but also has a service life of up to tens of thousands of hours to 100,000 hours. At the same time, it is not as fragile as traditional light bulbs, and can save electricity. At the same time, it is environmentally friendly and mercury-free. , Small size, can be used in low temperature environment, light source has directivity, causes less light damage and rich color gamut.
With the emergence of white LEDs and the introduction of more technology, the current lighting equipment in household appliances and notebook computers, automotive anti-fog lamps, indoor lighting and other lighting equipment is flourishing, and the application of LEDs is becoming more and more common.
The invention of LED
In 1955, Rubin Braunstein of Radio Corporation of America discovered the infrared radiation effect of gallium arsenide (GaAs) and other semiconductor alloys. In 1962, Nick Holonyak Jr of General Electric Company (GE) Developed visible light LEDLED. However, the real take-off of LEDs was after the emergence of white LEDs in the 1990s, and they began to be paid more and more attention, and their applications became wider and wider.
LED's light-emitting principle
LED is an electronic component that can convert electrical energy into light energy, and it also has the characteristics of a diode, that is, it has a positive electrode and a negative electrode. The most special feature of LED is that it will emit light only when it is energized from the positive electrode, so it is generally given When the DC power is applied, the LED will emit light steadily, but if it is connected to the AC power, the LED will flicker, and the flashing frequency depends on the frequency of the input AC power. The light-emitting principle of LEDs is to apply voltage to allow electrons and holes to combine in the semiconductor to release energy in the form of light. At present, different types of LEDs developed by the global industry can emit light of different wavelengths from infrared to blue, and the industry also has purple to ultraviolet LEDs. In recent years, the most attractive development of LEDs is to coat blue LEDs with phosphor. , A white LED product that converts blue light into white light. The reason why LED is called Century New Light Source is that LED has the characteristics of point light source and solid-state light source, which can save energy, high shock resistance, long life, small size, fast response, and high color saturation.
LED color:
As LEDs are made of different materials, the generated photons have different energy. Therefore, the industry uses manufacturing materials to control the wavelength of the LED's light emission, thereby producing various LEDs with different spectra and colors.
The material used in the world's first LED is arsenic (As) gallium (Ga), with a working voltage of 1.424V, and the light emitted by it is infrared spectrum. After that, the industry developed phosphorous (P) gallium (Ga) as the material for the LED, with a working voltage of 2.261V and the emitted light as green light. Early in the industry, through the materials required by these two types of LEDs, LED products of all wavelengths ranging from infrared to green light were deployed, and common red LEDs, yellow LEDs, orange LEDs, etc. were developed. The three types of LEDs are called 3-element LEDs because they use gallium, arsenic, and phosphorous, while blue LEDs, green LEDs, and infrared LEDs are called 2-element LEDs. The industry later developed a 4-element LED that mixed aluminum (Al), calcium (Ca), indium (In), and nitrogen (N), which can emit light in all visible light ranges and part of the ultraviolet spectrum.
LED brightness:
When discussing LED products, there are 3 units of luminous brightness, which are lux (Lux), luminous unit lumens (Lumen; lm), and luminous intensity unit candle (Candle power; CD). Each of the three units is suitable. The field of use, but the value is interoperable.
1 CD represents the luminous intensity of a completely radiant object, at the freezing point temperature of platinum, per sixtieth of an area of a square centimeter. It is suitable for use in the field of active light-emitting lamps, such as incandescent light bulbs.
1 lm represents the amount of light irradiated by 1 CD light on a plane with a distance of 1 cm and an area of 1 cm². It is suitable for use in reflective lamps and penetrating lamps, such as projectors.
1 Lux means the illuminance that 1 Lm of light is evenly distributed on an area of 1 square meter. Suitable for use in the field of photography.
Generally speaking, the luminous intensity of a single LED takes CD as the unit, coupled with the viewing angle parameter, and the luminous intensity of the LED ranges from mCD to 5,000 mCD. When the manufacturer labels a single LED product, its luminous intensity specification refers to the luminous intensity at the point of maximum luminous intensity at the best viewing angle and at the center position when the LED is lit under a current of 20 mA.
Energy-saving benefits of LED
Based on the environmental protection standpoint and energy conservation demands, governments around the world attach importance to the economic and energy-saving benefits brought by LEDs and energy-saving lamps, and manufacturers are also optimistic about the business opportunities of this lighting revolution and have invested in them. In addition to the phased ban on the use of incandescent bulbs in the European Union and the U.S. Congress, Canada has already announced a total ban on incandescent bulbs in 2010, and some states, including California, will also ban incandescent bulbs in 2012. Australia announced a total ban on the sale of incandescent light bulbs in 2010, and China and Japan also have LED incentive programs in the planning.
Although there is already another energy-saving fluorescent lamp (CFL) on the market, its lighting quality is still insufficient, the start-up time is longer than that of ordinary incandescent bulbs, and the light source output brightness cannot be adjusted, so the popularity is still not enough high. LED has more energy-saving benefits, and through the improvement of technology, the brightness has reached a satisfactory level, but the high price is a big problem. In the future, as the mass production of global LED manufacturers accelerates, the price can be accelerated after lowering the price. The popularity of LED lamps.
LED life:
Generally, the luminous life of LEDs is very long, and most products are marked as more than 100,000 hours, but in fact the brightness of LEDs will decay. After a period of use, the brightness will decay to half or even less. Fortunately, with the advancement of technology in the industry, there are many solutions to reduce the problem of LED brightness attenuation. In the production process, the use of 4 element LEC materials can have a longer brightness decay cycle, and the LED technology used by the manufacturer has a great relationship with the durability of the finished product. Color matching is also the key to the production of the LED factory.
The service life of LED is up to 50,000 hours compared with 1,000 hours of ordinary incandescent bulbs and 10,000 hours of daylight lamps, which greatly reduces the cost of lamp replacement. This feature helps LED lamps compete in price. There is a good reason to replace ordinary bulbs with LEDs. With this advantage, many environments that cannot be turned on all day due to economic considerations can be turned on by LED lighting. Make public or private places safer. For example, public parking lots, refrigerators, and other applications. The largest retailer in the United States, Wal-Mart, has recently changed the company's refrigeration equipment to power-saving LED products.
The more obvious shortcoming of LED is the heat dissipation problem. Improper heat dissipation will cause the luminosity and service life of LED lamps to be attenuated. Fortunately, this part is gradually improved by the blessing of new technology.
LED applications:
In addition to the LED indicators on various electronic products that we are familiar with, LED screens, LED lighting, LED backlights for LCD screens, LED backlights for buttons on mobile phones, new generation OLED screens, PLED screens, etc. The application of LEDs is gradually developing steadily. Because of the mature market development of LED applications in some areas, the speed of popularization has begun to accelerate, creating amazing business opportunities invisibly.
At present, high-brightness white LED light sources are currently the focus of research and development by LED manufacturers in the United States, Europe and Japan. It is estimated that after 2011, LEDs will be popular in the general lighting market on a large scale. Although Asia's high-brightness production scale accounted for 76% of the global market share in 2006, the white LED light source patents are held by the five major manufacturers of Nichia and TG in Japan, Cree in the United States, and Philips Lumileds and Osram in Europe; Although there are no standard specifications for midstream modules, they are still led by major international manufacturers including National, Laminar, Osram, Lumiled, and Vishay; the United States and Japan have also begun to actively formulate safety regulations and energy standards for lighting applications.
The biggest application of LED at this stage is the backlight of mobile phone buttons and the indicator lights of various electronic exhibits. Recently, the large-scale LED screens used in advertising billboards and the backlights used in LCD screens are also attracting more and more attention. The application is becoming more and more extensive. It is estimated that more LED products will be launched in the second half of 2007. In 2008, LED lighting products will be further reduced to a level acceptable to some consumers. The future development depends on the active application of LEDs in public utilities. Speed, is expected to accelerate the decline of LED prices, when consumers also increase the degree of adoption, the economic and energy-saving benefits will be considerable.
Global market development of LED:
In 2005, the global high-brightness LED market reached 5.8 billion U.S. dollars and reached 6.6 billion U.S. dollars in 2006. It is estimated to increase to 10.6 billion U.S. dollars in 2011, with an average annual growth rate (AAGR) of 10.2%. The shipment of high-brightness LEDs reached 4.8 billion units in 2005 and increased to 6.5 billion units in 2006, and is estimated to reach 8.8 billion units in 2011, with an average annual growth rate of 10.3%. In 2005, the sales of LED substrate materials exceeded US$1 billion and reached US$1.1 billion in 2006. It is estimated to be US$1.8 billion in 2011, with an average annual growth rate of 9.7%.
Taiwan’s LED lighting optoelectronic output value in 2006 was 21 billion NT dollars, which will increase to 93 billion yuan in 2010, and reach 540 billion yuan in 2015. In the upstream light source part, Taiwan's output is the world's largest. In 2006, the output value of high-brightness LEDs excluding mobile phone applications was as high as NT$15 billion. Taiwan’s upstream LED light source industry occupies an important position in the world because of its leading position in red and green LED technology. Downstream applications Taiwan's lighting production is of good quality, and price and global access are advantages. Taiwanese manufacturers account for 48% of the global market for liquid crystal panel (LCD) backlight modules. Therefore, Taiwanese manufacturers take this advantage to develop LED backlight modules, and automotive LED products are also regarded as one of the key projects.
It is estimated that LED will gradually replace existing incandescent lamps from 2007, and gradually replace fluorescent lamps from 2011. The European Union has phased out incandescent light bulbs since 2007, and Australia announced that incandescent light bulbs will be completely banned from 2010, so the LED market prospects are very worth looking forward to. In the next 5 years, the market application should use LED billboards or display backlights, automotive and general lighting as the main market development forces.
