nowcarLighting lamps have been incandescent lamps, halogen lamps, xenon lamps and so on. In addition to the headlights, other lamps, such as small lamps, indicator lights, and interior lights, mostly use incandescent lamps.But in recent years, LEDs have also become popular as indicators, such asbrakeIndicator lights, turn indicators, etc. Why is the rise of LEDs instead of incandescent lamps?
It turns out that LEDs have significant advantages compared with incandescent lamps. One is the long life span, generally up to tens of thousands or even 100,000 hours. Some people think that if LEDs are used in car lighting in the future, there will be no need to replace the lamps throughout the life of the car. Second, it is very energy-efficient, saving at least half of the electricity compared to incandescent lamps of the same brightness. The third is the high quality of light, basically no radiation, which is a "green" light source. Fourth, the structure of the LED is simple, the internal support structure is sealed with transparent epoxy resin, and the seismic performance is good. Fifth, there is no need for hot start time, and the light response speed is fast (nanosecond level), which is suitable for objects with fast moving speed. Sixth, the applicable voltage is between 6-12 volts, which can be used in automobiles. Seventh, the LED occupies a small volume, and the designer can change the lamp mode at will to make the car diversified. Automobile manufacturers' favor of LEDs is entirely determined by the advantages of LEDs themselves.
LED is the abbreviation of English Light Emitting Diode (Light Emitting Diode), which was produced as early as the 1960s. It has been widely used in household appliances in the 1980s, such as audio volume indicators,switchInstructions etc.In the 90s, some new domesticAuto MeterLEDs are also used on the board, mainly for charging instructions, and later to display the engineRotating speedFor example, on a combination instrument produced in Xiangfan, Hubei, there is a row of LEDs next to the odometer. When the driver steps on the accelerator, the LED lights will light up from bottom to top, and when the accelerator is released, the LED lights will go from top to bottom. Turn off one by one, quite eye-catching and beautiful. In the mid-1990s, my country used LEDs to do highbrake lightAnd install it in the car, because the LED lights up quickly, it can let the car driver behind the rear know the driving condition of the vehicle in front as soon as possible, and reduce the occurrence of car rear-end collision.
LED is a solid semiconductor element containing pn junction that can emit light by itself. The LED chip is a wafer composed of a p-type semiconductor and an n-type semiconductor. There is a transition layer between the p-type semiconductor and the n-type semiconductor, which is called a pn junction. When using semiconductor materials such as gallium arsenide (infrared), gallium arsenide phosphide (red to yellow), gallium phosphide (green), etc., in the pn junction of these semiconductor materials, the injected minority carriers and majority carriers During recombination, the excess energy is released in the form of light, thereby directly converting electrical energy into light energy. When a forward voltage is applied to the pn junction and current flows from the anode to the cathode of the LED, the semiconductor crystal emits light of different colors from ultraviolet to infrared. The intensity of the light is related to the current. However, due to the small luminous power of LEDs, they are generally only used for instructions and cannot be used for lighting. For lighting purposes, it is a new thing that has only appeared in recent years.
Since the luminous power of the LED is very small, many LEDs are generally made into an array type, and the small product is used as a practical indicator light. However, in this way, the cost will rise rapidly. Because the price of a high-quality LED is about 1.5 yuan, the price of dozens of them together far exceeds that of incandescent lamps. Since the LED luminous brightness is proportional to the current, the greater the input current, the higher the luminous brightness. Therefore, increasing the LED rated current and increasing the light output power are the focus of the factory's research and development. Only by increasing the luminous power of a single LED can the number of LEDs in the array be reduced, or even a single LED, to reduce costs. At present, the lighting industry has developed a single white LED with a luminous efficacy of 15 lumens/watt, which is equivalent to that of an incandescent lamp.
At the 2004 Beijing Auto Show, Leo France demonstrated its high-position brake light technology made of four LEDs, as well as using one LED to realize all tail signal light functions, including stop lights, rear small lights, turn indicators,Fog lightsAnd reversing indicator lights. This LED technology is suitable for all taillight functions. At the Ford booth, the front and rear lights of the Focus concept car for the future Chinese market all adopted LED technology. Some people predict that the two major bottlenecks of LED luminous power and cost will be solved in the next few years. In this way, not only automotive lighting, but even the entire lighting industry will undergo major changes.
Che Huitong
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