Taillights are used to make the backs of vehicles conspicuous at night or in bad weather. They produce red light and come on automatically whenever the headlights are illuminated. Car designers are free to combine tail lights with brake lights, which are brighter and signal the vehicle slowing down. The brightness ratio between tail lamps and stop lights is carefully specified by regulations. Light emitting diodes (LEDs) have become very popular light sources in automobile taillights. The Cadillac Deville was a pioneer user of LED lighting with their 1999 model.
Here are some reasons why auto makers are turning to LED taillights:
- Long service life
- Resistance to shock and vibration
- Allow for shallow packaging
- Energy efficiency
- Quick illumination means safer braking
LEDs were first used in center-mounted brake lights, followed by signal lights. They have now become something of a technological status symbol, and allow greater design freedom for car makers. Many cars have adopted LED lamps for projector headlights and taillights. It is now common for the low- and high-beams, as well as the parking lights and turn signals, to be made of LED lamps. In 2009, Lexus started using LEDs for side marker lamps.
The extended service life of LED lights figure prominently in their adoption by bus fleets and other commercial vehicles. Vehicle down-time is cut, and because of the light’s fast rise time, safety is enhanced. Commercial vehicles tend to standardize on light formats and fitments to keep costs down, and this has certainly been true for LED lights. You will also notice LED lights flashing on police cars, maintenance trucks and other beacon-wielding vehicles. You can leave LED lights on even with the engine off because they are so energy-efficient – they won’t deplete your battery even if left on for hours. This can be very important for running the emergency blinkers on a disabled car.
One downside of LED lamps is that they are sensitive to heat. High levels of heat will reduce performance and may even harm the light-transmitting components. Car makers package LED lamps in UV-protected modules that resist the sun’s rays. Internal components are also made with UV-resistance materials and feature thermal designs. The United Nations Economic Commission for Europe insists that signal lamps pass extended photometric tests for LED-equipped vehicles in order to evaluate the heat resistance of the lighting. They also test color rendering, UV radiation output and temperature stability of LED light sources. Head and tail lights must be able to withstand endurance tests devised by the UNECE.