Semiconductor lighting products have many advantages su […]
Semiconductor lighting products have many advantages such as high efficiency, energy saving, long life, environmental protection (no UV light pollution and mercury pollution), small size, solid devices, fast response, adjustable color temperature, easy integration and intelligent control, etc., and are considered to be the most valuable in the 21st century. Prospective new light sources have now replaced incandescent and fluorescent lamps on a large scale and become the dominant lighting market. But how did LED lighting products develop to this day and start the third revolution in the history of human lighting? What exactly is an LED? What are the structures of LED lighting products and where can they be applied? This article will explain the above issues in a simple way, so that LED lighting products not only formally reach thousands of stores, but also ordinary children and ordinary people can understand LED lighting products.
Two [photoelectric science popular knowledge]
What is the earliest lighting method in the history of human lighting?
In daily life, people mainly use their five sense systems: vision, hearing, smell, taste, and touch to obtain external information, and the visual system obtains the most information from the external environment, which is the people's daily work. People who want to quickly and correctly obtain external visual information not only need good vision, but a good light environment is also indispensable. Therefore, a good artificial lighting source is very important in dark or dark environments. The first artificial lighting source appeared 500,000 years ago. At that time, fire had been widely used by human beings, and the use of fire piles has been used for hundreds of thousands of years.
The earliest lighting method in the history of human lighting
The emergence of oil lamps is another important discovery in the history of human lighting, which is called the first revolution in the history of human lighting. The world's first real oil lamp made by mankind was to put some animal fat in a shallow bowl made of stone, and to achieve lighting by burning animal fat. The main disadvantage of the original grease lamp is that it emits smoke, which emits dark and dense smoke at the slightest fire. In order to reduce smoke, people invented the wick, reduced the speed of burning oil, overcome this problem, and greatly improved the efficiency of lighting based on heat.
Three [photoelectric science popular knowledge]
How did Edison invent incandescent lamps?
The invention of electricity has led humans to a new level in the pursuit of light. Electric lamps are the second revolution in the history of human lighting. The earliest principle of electric lighting appeared in 1808 when British scientist David used carbon rods to conduct thermal effects experiments of electric current. David accidentally touched the two carbon rods. Who knew that the moment when the tips of the carbon rods left each other, a very strong white light shone like a lightning in the night sky. After repeated experiments, he made an arc. The lamp is also called "electric candle".
Following the arc lamp, the wheel of history pushed the incandescent light onto the illuminated stage, and its booster was the well-known Edison experiment. Edison was inspired by the phenomenon that David platinum wire emits light, and after examining a large amount of data, he found the right direction for research: The key to manufacturing incandescent lamps is to find a kind of low resistance and resistance High temperature conductor material makes the filament. After testing more than 1,600 heat-resistant conductive materials of minerals and metals, in the end of 1879, Edison successfully made the world's first incandescent lamp using carbon filament as the filament, which continued to light for about 45 hours. In search of a more durable filament material, Edison used more than 6,000 types of plant fibers, and even his friend's red beard became his experimental material. Later, in the spring of 1880, he successfully used the charcoal wire burned with bamboo wire as the filament, which lengthened the incandescent lamp to 1200 hours. It was not until 1906 that tungsten filament was used instead. This is what we use now. Incandescent lamp.
The light-emitting principle of an incandescent lamp is to heat the filament to a high-temperature incandescent state, and then use thermal radiation to convert thermal energy into light, so it is also called a thermal light source. Later, people discovered the principle of gas discharge, which does not need to be heated to high temperature. The second is to rely on the bombardment of electrons and gas atoms in the lamp to excite light, which is called a cold light source. Among the gas discharge lamps, the first successful ones are fluorescent lamps, which use ultraviolet emission of mercury to excite photoluminescence. With the development of gas discharge lamps, a series of new light sources such as high-pressure mercury lamps, sodium lamps, and xenon lamps have gradually appeared, greatly improving the efficiency of the light source and the quality of lighting.
Four [photoelectric science popular knowledge]
What is the third human lighting revolution?
The third revolution in human lighting tools was the development of LED lights. In 1907, British scientist Henry Joseph Round first observed electroluminescence on a piece of silicon carbide. In the 1950s, British scientists used the semiconductor gallium arsenide in the electroluminescence experiments to invent the first LED of modern significance, and came out in the 1960s. In the late 1960s, the first visible red LED was invented using a phosphide on a gallium arsenide substrate. George Craford invented the first orange-yellow LED in 1972. In the mid-1990s, super-bright GaN LEDs appeared, and then green and blue indium-nitride-gallium LEDs that produced high-intensity were manufactured. The emergence of high-intensity blue-light LEDs has led to the emergence of white-light-emitting LEDs that excite YAG phosphors through blue-light chips, which has greatly promoted the development of LED lights.
Five [Photoelectric Science Popularization Knowledge]
Who is the Nobel Prize winner of LED? What contributions do they have?
From the development history of lighting, it can be seen that red LEDs and green LEDs have the longest existence and have been widely used in some indicators, but to form white light, red, green and blue primary colors must be mixed, both in the scientific community Still in the industry, how to create blue LEDs has plagued people for decades, which has made white light sources impossible to come out. In 1973, Akasaki, who was then at the Tokyo Research Institute of Panasonic Corporation, started the earliest research on blue LEDs. Later, Akasaki and Amano cooperated in the basic research and development of blue LEDs at Nagoya University. In 1989, the first blue LEDs were successfully developed. In 1990, Shuji Nakamura persisted for 10 years in loneliness. After many failures and constant explorations, he developed a blue high-brightness light-emitting diode. In 1993, the brightness of the blue light-emitting diode was increased to 100 times the original. Lighting technology innovation. The 2014 Nobel Prize in Physics was awarded to Japanese scientists Isamu Akasaki, Hiroshi Amano, and Japanese-American scientists Shuji Nakamura in recognition of their invention of the blue in the early 1990s. Colored light emitting diodes.