English
EspañolBefore introducing the characteristics and classification of LED, let's first understand the concept of LED. The so-called LED is the abbreviation of Light Emitting Diode in English, which means Light Emitting Diode in Chinese. It is a semiconductor device that can convert electrical energy into visible light, and often exists in a fixed state. The key core of LEDs is semiconductor chips, which are mainly composed of two parts: P-type semiconductors and N-type semiconductors.
2.1 Main characteristics of LED
Due to the principle of electric field luminescence adopted by LED, its characteristics are very obvious, which can be summarized as the following aspects:
(1) Long service life. The service life of a typical LED can reach around 10 years. This is because LED, unlike traditional light sources in the past, does not suddenly stop working or burn out like a tungsten filament lamp. Its damage is mainly due to the gradual weakening of its luminous performance over time. The LUXEON series products manufactured by Philips can maintain a luminous intensity of around 70% of the initial value after 50000 hours of use.
(2) Low maintenance costs. Under normal circumstances, the service life of LEDs is more than 10 times that of ordinary light sources, which greatly reduces the cost of replacing light sources, and correspondingly reduces maintenance and labor costs.
(3) Low energy consumption. Compared to fluorescent or incandescent lamps, LED has a much higher luminous efficiency. The LED emission rate of the XR-E model produced by Gree Company can reach over 1001m/W. From the perspective of energy conservation, the higher the Energy conversion efficiency is, the less electric energy is consumed under the same light, which is also one of the greatest advantages of LED.
(4) Small size. This feature is mainly aimed at LED chips. At present, the minimum volume of LED chips can reach the millimeter level. For example, Rebel, developed and manufactured by Lumileds in the United States, has a packaged volume of only 3x4.5x2.1 (in millimeters) and a chip size of only lmmx 1mm. Such a small volume is very convenient for optical design and can effectively reduce the energy loss of the system.
(5) Strong directionality. In terms of the distance of illumination, LED can definitely be designed as a point light source. In general, when conducting optical design, in order to simplify the design steps, it is customary to split the required light source into several point light sources, which can be replaced by LEDs. At the same time, LEDs can also be distributed on the surface of an object and simulate the shape of the object to emit light, such as landscape lighting, building contour lighting, etc.
(6) Solid-state lighting is green and environmentally friendly. LED belongs to Solid-state lighting light source, which does not contain glass materials that are easy to break, and has high impact resistance and shock resistance, so it can be used in relatively harsh environments. At the same time, LED does not contain toxic and harmful substances such as mercury, making it highly environmentally friendly. In addition, LEDs also do not contain infrared or ultraviolet light, which will not cause harm to the illuminated object and effectively improve the utilization rate of light energy.
(7) Low working voltage, suitable for working under low temperature conditions. The main working mode of LED is low-voltage DC power supply, which fully reflects its safety. At the same time, it can also work under low temperature conditions, and experiments have shown that it can work at -40 degrees Celsius. Based on this, it can be applied to lighting systems in refrigerators and automotive lighting systems.
2.2 LED classification
Currently, due to the promising market prospects of LED, there are more and more LED manufacturers, and there is no unified standard for LED classification in China. Usually, it can be classified based on chip power, color, and wavelength.
(1) Chip power. According to the power of LED chips, they can be divided into the following types: ① single lamps with output power of tens of mW, i.e. low-power chips; ② Power LED. Generally refers to LEDs with input power less than 1W; ③ High power LED. Specifically, it refers to LEDs with input power ≥ 1w.
(2) Luminous color and wavelength. The different wavelengths determine the different colors of light. According to the wavelength of LED light, it can be divided into infrared receiving tubes, reflecting tubes, and ultraviolet LEDs with wavelengths shorter than 390nm.
