LED is a new efficient and environmentally friendly semiconductor light source , there are other sources can not match advantage. Automotive lighting applications in the future bright prospects . led street light fixture Manufacturer can be combined in different ways in series or parallel and a LED array , in order to meet the strength requirements of automotive lighting . LED emission characteristics for , focused on the design and features of the LED driver , LED also outlined the current problems and solutions.
1 car headlights role and requirements
Currently, the automobile increasingly civilians, has become the main means of transport , road safety has aroused widespread concern. According to incomplete statistics , the car at night or natural light conditions odometer mileage of 25% of total travel , while traffic accidents occurred here accounted for 40 % of the total accidents , and more than half of the casualties occurred at night . Therefore , vehicle lights and car lights is a key component of safe driving , the following conditions must be met:
( 1 ) Automotive lighting lights without delay, faster response time , giving the driver more reaction time .
( 2 ) strong illumination to improve the driver's field of vision at night or in natural light conditions , while the role of outside lights indicating stronger .
( 3 ) high seismic , high reliability , to prevent accidents due to the lighting failure.
( 4 ) energy saving, can effectively reduce exhaust emissions and protect the environment.
( 5 ) Based on the increasingly competitive auto sales , lights designed to be practical and beautiful.
2 LED automotive lighting selection to become the new star
2.1 LED works
Special diode LED is formed by doping the semiconductor device means a PN junction. When the diode conduction condition is satisfied , a current flows through the LED, in the form of light and heat energy is released . LED is a current-mode current control element , the current size of the luminous intensity through the main basis when the forward pass , the drop is very high, and itself has a certain fluctuation range .
Since no infrared LED and ultraviolet radiation , the consumption of the energy is converted to light , almost all thermal energy in the form of heat conduction and only for outgoing , and therefore , LED during operation , the junction temperature will gradually rise. The LED is a device with a negative temperature coefficient , the current through the LED will increase with increasing temperature , which formed a positive feedback , causing the junction temperature rises further, if not controlled, it will burn LED. LED junction temperature has a lot of thermal parameters and the PN junction , the relationship between the dominant wavelength and temperature following formula :
mp (Tl) = m0 (T0) + 3Tg # 0.1nm / ° C
From the above equation , whenever the LED junction temperature rise 10 ℃, dominant wavelength ( the human eye can observe ) will shift to longer wavelengths 1nm (1nm = 10-9m), resulting in LED brightness down , there the light fades . Therefore , the individual LED overheating will cause the light-emitting LED array uniformity is deteriorated.
2.2 LED lighting significant advantage
LED light source is called new , because the LED light source and solid with characteristic point light source , so it has advantages over other lighting sources can not match.
(1) LED life of up to 100,000 hours in theory , the actual life expectancy can reach more than 20,000 hours , than incandescent bulbs 1000 hours, 10,000 hours lamp with the advantages , not normally required during the life of the car replacement.
( 2 ) light up without delay, faster response time . led street light fixture Manufacturer time of only tens of nanoseconds , start time than incandescent bulbs shortened.
( 3 ) In the light of high brightness, low visibility situations of natural light , greatly reducing the incidence of car accidents ; essentially no radiation , a " green light ."
(4) LED occupy small size, simple structure, high shock, designers are free to change the lamp mode , so diversified automotive styling , to meet the needs of different consumers .
( 5 ) Effect of change in voltage LED light source that is far less than the incandescent bulbs , shows excellent safety and reliability, while reducing the energy consumption of 80% compared with incandescent light efficiency is very energy efficient.
Based on the above advantages , LED can be widely used in automotive lighting , but a single LED can not meet the requirements of automotive lighting intensity must plurality of series , parallel or series-parallel to LED arrays .
more info you can visit:http://www.lead-lighting.com/products/sid108-1.htm
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