28-07-2012, 10:28 AM
Automotive lighting
Automotive lighting.doc (Size: 396.5 KB / Downloads: 47)
Colour of light emitted
Extensively redundant rear lighting installation on a Thai tour bus
The colour of light emitted by vehicle lights is largely standardised by longstanding convention, first codified in the 1949 Vienna Convention on Road Traffic[1] and later specified in the 1968 United Nations Convention on Road Traffic.[2] Generally, but with some regional exceptions, lamps facing rearward must emit red light, lamps facing sideward and all turn signals must emit amber light, lamps facing frontward must emit white or selective yellow light, and no other colours are permitted except on emergency vehicles.
[edit]Forward illumination
Forward illumination is provided by high- ("main", "full", "driving") and low- ("dip", "dipped", "passing") beam headlamps, which may be augmented by auxiliary fog lamps, driving lamps, or cornering lamps.
[edit]Headlamps
Dipped beam (low beam, passing beam, meeting beam)
Dipped-beam (also called low, passing, or meeting beam) headlamps provide a light distribution to give adequate forward and lateral illumination without dazzling other road users with excessive glare. This beam is specified for use whenever other vehicles are present ahead. The international ECE Regulations for headlamps specify a beam with a sharp, asymmetric cutoff preventing significant amounts of light from being cast into the eyes of drivers of preceding or oncoming cars.[3][4] Control of glare is less strict in the North American Society of Automotive Engineers (SAE) beam standard contained in FMVSS / CMVSS 108.[5]
Main beam (high beam, driving beam, full beam)
Main-beam (also called high, driving, or full beam) headlamps provide an intense, centre-weighted distribution of light with no particular control of glare. Therefore, they are only suitable for use when alone on the road, as the glare they produce will dazzle other drivers. International ECE Regulations permit higher-intensity high-beam headlamps than are allowed under North American regulations[6]
[edit]Auxiliary lamps.
Cornering lamps
A cornering lamp on a 1983 Oldsmobile 98.
On some models, white "cornering lamps" provide extra lateral illumination in the direction of an intended turn or lane change. These are actuated in conjunction with the turn signals, though they burn steadily, and they may also be wired to illuminate when the vehicle is shifted into reverse gear,[15] as is done on many Saabs and Corvettes. North American technical standards contain provisions for front cornering lamps[16] as well as for rear cornering lamps.[17] Cornering lamps have traditionally been prohibited under international ECE Regulations, though provisions have recently been made to allow them as long as they are only operable when the vehicle is travelling at less than 40 kilometres per hour (about 25 mph).[15][18]
Spot lights
Police cars, emergency vehicles, and those competing in road rallies are sometimes equipped with an auxiliary lamp, sometimes called an alley light, in a swivel-mounted housing attached to one or both a-pillars, directable by a handle protruding through the pillar into the vehicle. Until the mid-1940s, these spot lamps could be found as standard equipment on expensive cars.[which?] Until the mid-1960s, they were commonly offered by automakers as model-specific accessory items.[citation needed] Spot lamps are used to illuminate signs, house numbers, and people. Spot lights can also be had in versions designed to mount through the vehicle's roof. In some countries, for example in Russia, spot lights are allowed only on emergency vehicles or for off-road driving.[citation needed]
Conspicuity, signal and identification lights
A North American 1991 Acura Integrawith parking lamps, hazard flashers, fog lights and side marker lamps illuminated
Conspicuity devices are the lamps and reflectors that make a vehicle conspicuous and visible with respect to its presence, position, direction of travel, change in direction or deceleration. Such lamps may burn steadily, blink, or flash, depending on their intended and regulated function.