A headlamp is a lamp, usually attached to the front of a vehicle such as a car, with the purpose of illuminating the road ahead during periods of low visibility, such as night or precipitation. A lamp is a replaceable component such as an Incandescent light bulb, which is designed to produce Light from Electricity. Vehicles, derived from the Latin word vehiculum, are non-living Means of transport. In Meteorology, visibility is a measure of the Distance at which an object or light can be clearly discerned In Meteorology, precipitation (also known as one class of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric While it is common for the term headlight to be used interchangeably in informal discussion, headlamp is the technically correct term for the device itself, while headlight properly refers to the beam of light produced and distributed by the device. A light beam or beam of light is a narrow Projection of Light energy radiating from a source into a Beam.
A headlamp can also be mounted on a bicycle (with a battery or small electrical generator), and most other vehicles from airplanes to trains tend to have headlamps of their own. Bicycle lighting has two purposes seeing and being seen There are many types of Bicycle lights available each with its own advantages and disadvantages In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy In Electricity generation, an electrical generator is a device that converts Mechanical energy to Electrical energy, generally using Electromagnetic Overview Fixed-wing aircraft range from small training and recreational aircraft to Wide-body aircraft and military cargo aircraft. A train is a connected series of vehicles that move along a track ( Permanent way) to transport freight or passengers from one place to another
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History of automotive headlamps
Mechanics
The earliest headlamps were fueled by acetylene or oil and were introduced in the late 1880s. Acetylene ( IUPAC name ethyne), C2H2 is a Hydrocarbon belonging to the group of Alkynes It is the simplest of all alkynes An oil is a substance that is in a viscous Liquid state ( "oily") at ambient temperatures or slightly warmer and is Acetylene lamps were popular because the flame was resistant to wind and rain. Carbide lamps, also known as acetylene gas lamps, are simple lamps that produce and burn Acetylene (C2H2 which is created by the reaction The first electric headlamps were introduced in 1898 on the Columbia Electric Car from the Electric Vehicle Company of Hartford, Connecticut, and were optional. Two factors limited the widespread use of electric headlamps: the short life of filaments in the harsh automotive environment, and the difficulty of producing dynamos small enough, yet powerful enough to produce sufficient current. [1] "Prest-O-Lite" acetylene lights were offered by a number of manufacturers as standard equipment for 1904, and Peerless made electrical headlamps standard in 1908. Peerless was a United States automobile produced by the Peerless Motor Company of Cleveland Ohio. In 1912, Cadillac integrated their vehicle's Delco electrical ignition and lighting system, creating the modern vehicle electrical system. Cadillac is a Brand of Luxury vehicles owned by General Motors.
"Dipping" (low beam) headlamps were introduced in 1915 by the Guide Lamp Company, but the 1917 Cadillac system allowed the light to be dipped with a lever inside the car rather than requiring the driver to stop and get out. The 1924 Bilux bulb was the first modern unit, having the light for both low (dipped) and high (main) beams of a headlamp emitting from a single bulb. A similar design was introduced in 1925 by Guide Lamp called the "Duplo". In 1927, the foot-operated dimmer was introduced and became standard for much of the century. The last vehicle with a foot-operated dimmer was the 1991 Ford F-Series. For the 1999-present F-250 and higher models see Ford Super Duty. Foglamps were new for 1938 Cadillacs, and their 1954 "Autronic Eye" system automated the switch between high and low beams.
The standardized 7 in (178 mm) round sealed beam headlamp was introduced in 1940, and was soon required for all vehicles sold in the United States. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of The United States of America —commonly referred to as the Britain, Australia and other Commonwealth countries, as well as Japan, also made extensive use of 7 in. sealed beams. With some exceptions from Volvo and Saab, this headlamp size format was never widely accepted in Europe, leading to different front-end designs for each side of the Atlantic for decades. This article is about Volvo Group - AB Volvo Volvo Cars is the passenger vehicle maker owned by Ford Motor Company, using the Volvo Trademark Saab AB is an Aerospace and defense company based in Sweden. History "Svenska Aeroplan AB (aktiebolaget" ( Swedish for
The first halogen headlamp for vehicle use was introduced in 1962 by a consortium of European bulb and headlamp makers. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions Halogen technology makes incandescent filaments more efficient and can produce more light than from non-halogen filaments at the same power consumption. Incandescence is the emission of Light (visible Electromagnetic radiation) from a hot body due to its temperature These were prohibited in the US, where non-halogen sealed beam lamps were required until 1978. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of From 1978 to 1983, all halogen headlamps in the U. S. were sealed beams with halogen bulbs inside. These halogen sealed beams remain available, 25 years after replaceable-bulb headlamps returned to the US in 1983.
High-intensity discharge systems were introduced in 1991's BMW 7-series. A High-intensity discharge (HID lamp is a type of electrical lamp which produces light by means of an electric arc between Tungsten Electrodes In 1987 BMW introduced the second generation of the 7 series, known internally as the E32. European and Japanese markets began to prefer HID headlamps, with as much as 50% market share in those markets, but they found slow adoption in North America. 1996's Lincoln Mark VIII was an early American effort at HIDs, and was the first and only car with DC HIDs. See Lincoln Mark for a complete overview of the Lincoln Mark Series Direct current ( DC) is the unidirectional flow of Electric charge.
Design & Style
Beyond the engineering, performance and regulatory-compliance aspects of headlamps, there is the consideration of the various ways they are designed and arranged on a motor vehicle. Early headlamps were round, because that is the easiest shape for parabolic reflector manufacture. In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular
Headlamp styling outside of the United States, pre-1983
There was no requirement in Europe for headlamps of standardised size or shape. The Citroën DS (also known as Déesse, or Goddess, after the punning initials in French is an Executive car that was produced by Automakers were free to design their lamps to whatever shapes and sizes they wished, as long as the lamps met the engineering and performance requirements contained in the applicable European safety standards. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE That design freedom permitted the development of rectangular headlamps, first used in 1961. Developed by Cibié for the Citroën Ami 6 and by Hella for the German Ford Taunus, they were prohibited in the United States where round lamps were required until 1975. The Citroën Ami (French for "friend" is a supermini produced by the French automaker Citroën from 1961 to 1978 Hella KGaA Hueck & Co is a German company that manufactures Automotive lighting devices such as Headlamps signal lamps and the Electronics Ford Taunus was a range of Family cars sold by Ford in Germany and other countries A trade restriction is an artificial restriction on the trade of goods between two countries Another early headlamp styling concept involved conventional round lamps faired into the car's bodywork with aerodynamic glass covers, such as those on the 1961 Jaguar E-Type. The Jaguar E-Type' (UK or XK-E (US is a British Automobile, manufactured by Jaguar between 1961 and 1974
Headlamp styling in the United States, 1940-1983
In 1940, the US government mandated a system of two 7 in. (178 mm) round sealed beam headlamps on all vehicles. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of Headlamp styling in the United States virtually ceased for many decades after this event.
A system of four round lamps, rather than two—one high/low and one high-beam 5¾ in. (146 mm) sealed beam on each side—were introduced in 1952 when the Prevost Car company included them in its Citaden bus model. Prevost Car is a Quebec, Canada -based manufacturer of touring coaches and bus shells for high-end motorhomes and specialty conversions Cadillac, Chrysler and Nash placed them in some of their car models in states that permitted the new system for the 1957 model year, and other American marques followed suit when all states permitted quad lamps in 1958. These lamps had some photometric advantages, but the primary advantage was the styling novelty permitted by the use of two small rather than one large lamp per side of the vehicle. This article deals with the usage of this term in Optics and Lighting. The freedom was not absolute, however. Auto stylists such as Virgil Exner carried out design studies with the low beams in their conventional outboard location, and the high beams vertically stacked at the centerline of the car. Virgil Max "Ex" Exner Sr was an Automobile Designer for numerous American companies notably Chrysler and Studebaker No such designs reached volume production. Most cars had their headlights in pairs side by side on each side of the car. Some Oldsmobiles had a parking light in the middle of each pair. Oldsmobile was a brand of Automobile produced for most of its existence by General Motors.
Also popular was an arrangement in which the two headlamps on each side were stacked, low beams above high beams. Nash used this arrangement in the 1957 model year. Pontiac used this design starting in the 1963 model year; American Motors, Ford, Cadillac and Chrysler followed two years later. Pontiac is a Brand of Automobiles produced by General Motors that has been sold in the United States, Canada and Mexico American Motors Corporation (AMC was an American automobile company formed on January 14 1954 by the merger of the Nash-Kelvinator Corporation Ford Motor Company is an American Multinational corporation and the world's fourth largest automaker based on Worldwide vehicle sales, following Cadillac is a Brand of Luxury vehicles owned by General Motors. Chrysler LLC is an American Automobile manufacturer that has been producing Automobiles since 1925 Also in the 1965 model year, the Buick Riviera had concealable stacked headlamps. The Buick Riviera was an Automobile produced by Buick in the United States from the 1963 to 1999 Model years with 1127261 produced The Mercedes-Benz W100, W108, W111, and W112 models sold in America used this arrangement because their home-market composite lamps were illegal in the US. Mercedes-Benz is a German manufacturer of luxury Automobiles Buses coaches and Trucks It is currently a division of the See also Mercedes-Benz 600 (disambiguation for other models called "600" The Mercedes-Benz 600 was a large luxury Automobile See Mercedes-Benz S-Class for a complete overview of all S-Class models See Mercedes-Benz S-Class for a complete overview of all S-Class models See Mercedes-Benz S-Class for a complete overview of all S-Class models The British firm Alvis and the French firm FACEL also used this setup for some of their cars, as did Nissan in Japan. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located This article is about the country For a topic outline on this subject see List of basic France topics. For a topic outline on this subject see List of basic Japan topics.
In the late 1950s and early 1960s, Lincoln, Buick, and Chrysler arranged the headlamps diagonally by placing the low-beam lamps outboard and above the high-beam lamps. Lincoln is an American Luxury car manufacturer operated under the Ford Motor Company. Buick (ˈbjuːɪk is a Marque of automobile sold in the United States, Canada, China, Taiwan, Qatar, and Chrysler LLC is an American Automobile manufacturer that has been producing Automobiles since 1925 Certain British cars used a less extreme diagonal arrangement, with the inboard high-beam lamps placed only slightly lower than the outboard low-beam units. The 1965 Gordon-Keeble, Triumph Vitesse and Bentley S3 Continental used such an arrangement. Gordon-Keeble was a British car marque made first in Slough, then Eastleigh, and finally in Southampton (all in England) between The Triumph Vitesse was a compact 6-cylinder car built by Standard-Triumph from 1962&ndash71 The Bentley S3 was a Luxury car produced by Bentley from 1962 until 1965 (source: World Car Catalog)
In 1968 the U.S. DOT prohibited any decorative or protective element in front of the headlamps whenever the headlamps are switched on. The United States Department of Transportation ( DOT) is a federal Cabinet department of the United States government concerned with Transportation A trade restriction is an artificial restriction on the trade of goods between two countries Glass-covered headlamps, used on e. g. the Jaguar E-Type, the pre-1968 VW Beetle, the Porsche 356, the Citroën DS and Ferrari Daytona were no longer permitted, and vehicles had to be imported with uncovered headlamps for the US market. The Jaguar E-Type' (UK or XK-E (US is a British Automobile, manufactured by Jaguar between 1961 and 1974 The Volkswagen Beetle, officially known as the type 1 and originally called ‘Käfer’ is an Economy car produced by the German auto maker Volkswagen The Porsche 356 was the company's first production automobile The Citroën DS (also known as Déesse, or Goddess, after the punning initials in French is an Executive car that was produced by Vehicle specifications The engine known as a Tipo 251 and developed from the earlier Lampredi V12 used in the 275 GTB/4 was a 4 This change meant that vehicles designed for good aerodynamic performance could not achieve it for the US market.
When Federal Motor Vehicle Safety Standard 108 was amended in the early 1970s to permit rectangular headlamps, these were placed in horizontally-arrayed or vertically-stacked pairs. Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States. In Geometry, a rectangle is defined as a Quadrilateral where all four of its angles are Right angles A rectangle with vertices ABCD would be denoted as By 1979, the majority of new cars in the US market were equipped with rectangular lamps. Again, the US permitted only two standardized sizes of rectangular sealed-beam lamp: A system of two 200 mm × 142 mm (7½ in. × 5½ in. ) high/low beam units corresponding to the existing 7-inch round format, or a system of four 165 mm x 100 mm (6½ in. × 4 in. ) units, two high/low and two high-beam, corresponding to the existing 5¾-inch (146 mm) round format.
International headlamp styling, 1983 to present
In 1983, the 44-year-old US headlamp regulations were amended to allow replaceable-bulb, nonstandard-shape, architectural headlamps with aerodynamic lenses. The National Highway Traffic Safety Administration ( NHTSA, often pronounced "nit-suh" is an agency of the Executive Branch of the U The first U. S. -market car since 1939 with composite headlamps was the 1984 Lincoln Mark VII. See Lincoln Mark for a complete overview of the Lincoln Mark Series These composite headlamps were commonly referred to as "Euro" headlamps, since aerodynamic headlamps were common in Europe. Though conceptually similar to European headlamps with nonstandardized shape and replaceable-bulb construction, these headlamps conform to the SAE headlamp standards of US Federal Motor Vehicle Safety Standard 108, and not the internationalized European safety standards used outside North America. SAE International (SAE is a professional organization for mobility engineering professionals in the Aerospace, Automotive, and commercial Vehicle industries Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE Nevertheless, this change to US regulations largely united headlamp styling within and outside the North American market.
In the late 1990s, round headlamps returned to popularity on new cars. These are generally not the discrete self-contained round lamps as found on older cars (certain Jaguars excepted), but rather involve circular or oval optical elements within an architecturally-shaped housing assembly. Jaguar Cars Limited is a luxury car manufacturer based in Coventry, England, now operated as part of the Jaguar Land Rover business
Hidden headlamps
Hidden headlamps were introduced in 1936, on the Cord 810. Hidden headlamps are an automotive styling feature that conceals an Automobile 's Headlamps when they are not in use The Mazda Familia Astina was Mazda's sportier five-door Fastback version of the well established Familia Cord was the Brand name of a United States Automobile, manufactured by the Auburn Automobile Company from 1929 through 1932 and again They were mounted in the front fenders, which were smooth until the lights were cranked out, each with its own small dash-mounted crank. They aided aerodynamics when the headlamps were not in use, and were among the Cord's signature design features.
Many notable cars used this feature, but no current volume-produced car models use hidden headlamps, largely because of their expense. The system requires one or more vacuum-operated servos and reservoirs, with associated plumbing and linkage, or electric motors, geartrains and linkages to raise the lamps to an exact position to assure correct aiming despite ice, snow and age. A servomechanism, or servo is an automatic device which uses error-sensing Feedback to correct the performance of a mechanism An electric motor uses Electrical energy to produce Mechanical energy. This is the page for mechanical Gears For other uses see Gear (disambiguation For the gear-like device used to drive a roller chain see Sprocket Some early hidden headlamps, such as those on the Saab Sonett III, used a lever-operated mechanical linkage to raise the headlamps into position. Saab Sonett is the name of a series of Automobiles from Saab. Current market demands place a premium on vehicles' aerodynamic performance with lamps off and on, further reducing the attractiveness of pop-up headlamps. In addition, recent ECE regulations contain standards regarding protuberances on car bodies to minimize injury to pedestrians struck by cars. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE A pedestrian is a person travelling on foot whether Walking or Running.
Some hidden headlamps themselves do not move, but rather are covered when not in use by panels designed to blend in with the car's styling. When the lamps are switched on, the covers are swung out of the way, usually downward or upward, for example on the 1992 Jaguar XJ220. The Jaguar XJ220 is a mid-engined Sports car produced by Jaguar in collaboration with Tom Walkinshaw Racing as Jaguar Sport between 1992 The door mechanism may be actuated by vacuum pots, as on some Ford vehicles of the late 1960s through early 1980s such as the 1967-1969 Mercury Cougar, or by an electric motor as on various Chrysler products of the middle 1960s through late 1970s such as the 1966-1967 Dodge Charger. Manifold vacuum, or engine Vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Ford Motor Company is an American Multinational corporation and the world's fourth largest automaker based on Worldwide vehicle sales, following The Mercury Cougar was an Automobile sold under the Mercury brand of the Ford Motor Company 's Lincoln-Mercury Division The Dodge Charger is an American Automobile manufactured by Chrysler, under the Dodge brand name
Regulations and requirements
Modern headlamps are electrically operated, positioned in pairs, one or two on each side of the front of a vehicle. A headlamp system is required to produce a low and a high beam, which may be achieved either by an individual lamp for each function or by a single multifunction lamp. High beams (called "main beams" or "full beams" or "driving beams" in some countries) cast most of their light straight ahead, maximizing seeing distance, but producing too much glare for safe use when other vehicles are present on the road. Glare is difficulty seeing in the presence of bright Light such as direct or reflected Sunlight or artificial light such as car Headlamps at night Because there is no especial control of upward light, high beams also cause backdazzle from fog, rain and snow due to the retroflection of the water droplets. Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. A drop or droplet is a small volume of Liquid, bounded completely or almost completely by Free surfaces Surface tension Low beams (called "dipped beams" in some countries) have stricter control of upward light, and direct most of their light downward and either rightward (in right-traffic countries) or leftward (in left-traffic countries), to provide safe forward visibility without excessive glare or backdazzle.
Low and high beams
Low beam
Low beam (dipped beam, passing beam, meeting beam) headlamps provide a distribution of light designed to provide adequate forward and lateral illumination with limits on light directed towards the eyes of other road users, to control glare. This beam is intended for use whenever other vehicles are present ahead. The international ECE Regulations for filament headlamps[2] and for high-intensity discharge headlamps[3] 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. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE Control of glare is less strict in the North American SAE beam standard contained in FMVSS / CMVSS 108[4] . SAE International (SAE is a professional organization for mobility engineering professionals in the Aerospace, Automotive, and commercial Vehicle industries Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States.
High beam
High beam (main beam, driving beam, full beam) headlamps provide a bright, centre-weighted distribution of light with no particular control of light directed towards other road users' eyes. As such, 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[5]. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States.
Some countries require automobiles to be equipped with automatic daytime running lamps (DRL), which are intended to increase the conspicuity of vehicles in motion during the daytime. A daytime running lamp ( DRL, also daylight running lamp or daytime running light) is a lighting device on the front of a roadgoing Motor DRL may consist of the manual or automatic illumination of the low beams at full or reduced intensity, or the high beams at reduced intensity, or may not involve the headlamps at all. Countries requiring DRL include Canada, Iceland, Hungary, Poland, Slovenia and most Scandinavian countries.
Compatibility with traffic directionality
Most low-beam headlamps are specifically designed for use on only one side of the road. Right-hand traffic and left-hand traffic mean regulations requiring all traffic to keep either to the left or the right side of the Road. Headlamps for use in left-traffic countries have low-beam headlamps that "dip to the left"; the light is distributed with a downward/leftward bias to show the driver the road and signs ahead without blinding oncoming traffic. Headlamps for right-traffic countries have low beams that "dip to the right", with most of their light directed downward/rightward. Within Europe, when driving a vehicle with RH-traffic headlamps in a LH-traffic country or vice versa for a limited time (as for example on vacation or in transit), it is a legal requirement to adjust the headlamps temporarily so that the wrong-side hot spot of the beam does not dazzle oncoming drivers. This may be achieved by adhering blackout strips or plastic prismatic lenses to a designated part of the lens, but some varieties of the projector-type headlamp can be made to produce a proper left- or right-traffic beam by shifting a lever or other movable element in or on the lamp assembly.
Because wrong-side-of-road headlamps blind oncoming drivers and do not adequately light the driver's way, and blackout strips and adhesive prismatic lenses reduce the safety performance of the headlamps, most countries require all vehicles registered or used on a permanent or semipermanent basis within the country to be equipped with headlamps designed for the correct traffic-handedness. North American vehicle owners sometimes privately import and install Japanese-market (JDM) headlamps on their car in the mistaken belief that the beam performance will be better, when in fact such misapplication is quite hazardous and usually illegal. Japanese Domestic Market ( JDM) is a term for Japan 's economic market for Japanese-brand goods such as Automobiles and parts [6]
Construction, performance, and aim
There are two different beam pattern and headlamp construction standards in use in the world: The ECE standard, which is allowed or required in virtually all industrialized countries except the United States, and the SAE standard that is mandatory only in the US. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE SAE International (SAE is a professional organization for mobility engineering professionals in the Aerospace, Automotive, and commercial Vehicle industries Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States. Japan formerly had bespoke lighting regulations similar to the US standards, but for the left side of the road. However, Japan now adheres to the ECE standard. The differences between the SAE and ECE headlamp standards are primarily in the amount of glare permitted towards other drivers on low beam (SAE permits much more glare), the minimum amount of light required to be thrown straight down the road (SAE requires more), and the specific locations within the beam at which minimum and maximum light levels are specified.
ECE low beams are characterized by a distinct horizontal "cutoff" line at the top of the beam. Below the line is bright, and above is dark. On the side of the beam facing away from oncoming traffic (right in right-traffic countries, left in left-traffic countries), this cutoff sweeps or steps upward to direct light to road signs and pedestrians. SAE low beams may or may not have a cutoff, and if a cutoff is present, it may be of two different general types: VOL, which is conceptually similar to the ECE beam in that the cutoff is located at the top of the left side of the beam and aimed slightly below horizontal, or VOR, which has the cutoff at the top of the right side of the beam and aimed at the horizon. [7]
Proponents of each headlamp system decry the other as inadequate and unsafe: U. S. proponents of the SAE system claim that the ECE low beam cutoff gives short seeing distances and inadequate illumination for overhead road signs, while international proponents of the ECE system claim that the SAE system produces too much glare[8]. Comparative studies have repeatedly shown that there is little or no overall safety benefit to either SAE or ECE beams; the two systems' acceptance and rejection by various countries is based primarily on inertial and philosophical grounds. [7],[9]
In North America, the design, performance and installation of all motor vehicle lighting devices are regulated by Federal and Canada Motor Vehicle Safety Standard 108, which incorporates SAE technical standards. Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States. SAE International (SAE is a professional organization for mobility engineering professionals in the Aerospace, Automotive, and commercial Vehicle industries Elsewhere in the world, ECE internationalised regulations are in force either by reference or by incorporation in individual countries' vehicular codes. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE
US laws required sealed beam headlamps on all vehicles between 1940 and 1983, and other countries such as Japan, United Kingdom and Australia also made extensive use of sealed beams. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of In most other countries, and in the US since 1984, replaceable-bulb headlamps predominate.
Headlamps on new vehicles must produce white light, according to both ECE and SAE standards. Previous ECE regulations also permitted selective yellow light, which from 1936 until 1993 was required on all vehicles registered in France. Selective yellow is a colour for automotive lamps. Under ECE regulations, Headlamps were formerly permitted to be either White or selective yellow — Year 1936 ( MCMXXXVI) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian calendar. Year 1993 ( MCMXCIII) was a Common year starting on Friday (link will display full 1993 Gregorian calendar) This article is about the country For a topic outline on this subject see List of basic France topics. Yellow headlamps are no longer required anywhere, but remain permitted in France, Belgium, The Netherlands, Switzerland, Japan, New Zealand, and some other countries. The Kingdom of Belgium is a Country in northwest Europe. It is a founding member of the European Union and hosts its headquarters as well as those The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation For a topic outline on this subject see List of basic Japan topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island
Headlamps must be kept in proper alignment (or "aim"). Regulations for aim vary from country to country and from beam specification to beam specification. US SAE headlamps are aimed without regard to headlamp mounting height. This gives vehicles with high-mounted headlamps a seeing distance advantage, at the cost of increased glare to drivers in lower vehicles. ECE headlamps' aim angle is linked to headlamp mounting height. This gives all vehicles roughly equal seeing distance and all drivers roughly equal glare. [10]
Optical systems
Reflector lamps
Lens optics
 Lens optics, side view. Light is dispersed vertically (shown) and laterally (not shown). | _-_headlamp.jpg/207px-Jaguar_E-type_(serie_III)_-_headlamp.jpg) A 7 in. round sealed-beam headlamp with lens optics on a Jaguar E-type. The Jaguar E-Type' (UK or XK-E (US is a British Automobile, manufactured by Jaguar between 1961 and 1974 The flutes and prisms spread and distribute the light collected by the reflector. |
A light source (filament or arc) is placed at or near the focus of a reflector, which may be parabolic or of non-parabolic complex shape. An electrical filament is a thread of Metal, usually Tungsten, which is used to convert Electricity into light in Incandescent light bulbs (as developed In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular Fresnel and prism optics moulded into the headlamp lens then shift parts of the light laterally and vertically to provide the required light distribution pattern. A Fresnel lens (pronounced or) is a type of lens invented by French physicist Augustin-Jean Fresnel. In Optics, a prism is a transparent optical element with flat polished surfaces that refract Light. The lens may use both refraction and TIR to achieve the desired results. Refraction is the change in direction of a Wave due to a change in its Speed. Most sealed-beam headlamps have lens optics. [11]
Reflector optics
 Reflector optics, side view |  A reflector-optic headlamp on a Jeep Liberty. The Jeep Liberty (KJ/KK or Jeep Cherokee (KJ/KK outside North America is a Compact SUV produced by the Jeep marque of Chrysler. The clear front cover lens serves only a protective function. |
Starting in the 1980s, CAD technology allowed the development of reflector headlamps with nonparabolic, complex-shape reflectors. First made by Valeo under their Cibié brand, these headlamps would revolutionize automobile design. Valeo is a French automotive components manufacturer History The Société Anonyme Française du Ferodo was founded in 1923 in Saint-Ouen a suburb of Paris The 1987 Dodge Monaco/Eagle Premier was the first U. S. -market car with complex-reflector headlamps, while the 1990 Honda Accord was the first U. The Honda Accord is series of midrange Automobile manufactured by Honda since 1976 and sold in most automotive markets throughout the world S. -market car with such headlamps employing a completely clear, nonfaceted front lens.
The optics to distribute the light in the desired pattern are designed into the reflector itself, called an "optic reflector". Depending on the development tools and techniques in use, the reflector may be engineered from the start as a bespoke shape, or it may start as a parabola standing in for the size and shape of the completed package. In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular In the latter case, the entire surface area is modified so as to produce individual segments of specifically calculated, complex contours. The shape of each segment is designed such that their cumulative effect produces the required light distribution pattern. [11]
Optic reflectors are commonly made of compression-moulded or injection molded plastic, though glass and metal optic reflectors also exist. Compression molding is a method of Molding in which the molding material generally preheated is first placed in an open heated Mold cavity Injection molding (British moulding The reflective surface is vapor deposited aluminum with a clear overcoating to prevent the extremely thin aluminum from oxidizing. Extremely tight tolerances must maintained in the design and production of complex-reflector headlamps.
Dual-beam reflector headlamps
Night driving has long been dangerous due to the glare of headlights from oncoming traffic which temporarily blinds approaching drivers. Headlamps that satisfactorily illuminate the road ahead without causing glare have long been sought. The first solutions involved resistance-type dimming circuits, which decreased the brightness of the headlamps. This yielded to tilting reflectors, and later to double-filament bulbs with a high and a low beam. Automatic headlamp dimmers were also introduced.
In a two-filament headlamp, there can only be one filament exactly at the focal point of the reflector. There are two primary means of producing two different beams from a two-filament bulb in a single reflector.
American system
One filament is located at the focal point of the reflector. The other filament is shifted axially and radially away from the focal point. In most 2-filament sealed beams and in 2-filament replaceable bulbs type 9004, 9007 and H13, the high beam filament is at the focal point and the low beam filament is off focus. For use in right-traffic countries, the low beam filament is positioned slightly upward, forward and leftward of the focal point, so that when it is energized, the light beam is widened and shifted slightly downward and rightward of the headlamp's axis. Transverse-filament bulbs such as 9004 can only be used with the filaments horizontal, but axial-filament bulbs can be rotated or "clocked" by the headlamp designer so as to optimize the beam pattern or to effect the traffic-handedness of the low beam. The latter is accomplished by clocking the low-beam filament in an upward-forward-leftward position to produce a right-traffic low beam, or in an upward-forward-rightward position to produce a left-traffic low beam.
The opposite tactic has also been employed in certain 2-filament sealed beams. Placing the low beam filament at the focal point to maximize light collection by the reflector, and positioning the high beam filament slightly rearward-rightward-downward of the focal point. The relative directional shift between the two beams is the same with either technique—in a right-traffic country, the low beam is slightly downward-rightward and the high beam is slightly upward-leftward, relative to one another—but the lens optics must be matched to the filament placements selected.
European system
The traditional European method of achieving low and high beam from a single bulb involves two filaments along the axis of the reflector. The high beam filament is on the focal point, while the low beam filament is approximately 1 cm forward of the focal point and 3 mm above the axis. Below the low beam filament is a cup-shaped shield (called a "Graves Shield") spanning an arc of 165°. Circles are simple Shapes of Euclidean geometry consisting of those points in a plane which are at a constant Distance, called the When the low beam filament is illuminated, this shield casts a shadow on the corresponding lower area of the reflector, blocking downward light rays that would otherwise strike the reflector and be cast above the horizon. The bulb is rotated (or "clocked") within the headlamp to position the Graves Shield so as to allow light to strike a 15° wedge of the lower half of the reflector. This is used to create the upsweep or upstep characteristic of ECE low beam light distributions. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE The bulb's rotative position within the reflector depends on the type of beam pattern to be produced and the traffic directionality of the market for which the headlamp is intended. Right-hand traffic and left-hand traffic mean regulations requiring all traffic to keep either to the left or the right side of the Road.
This system was first used with the Bilux/Duplo R2 bulb of 1954, and later with the halogen H4 bulb of 1971. A halogen lamp is an Incandescent lamp in which a Tungsten filament is sealed into a compact transparent envelope filled with an inert gas plus a small amount of In 1992, U. S. regulations were amended to permit the use of H4-style bulbs. Named HB2 or 9003, for the U. S. market, and with slightly different production tolerances stipulated, these bulbs are physically and electrically interchangeable with H4 bulbs. Similar optical techniques are used, but with different reflector and/or lens optics to create a US beam pattern rather than a European one.
Each system has its advantages and disadvantages. The American system historically permitted a greater overall amount of light within the low beam, since the entire reflector and lens area is used, but at the same time, the American system has traditionally offered much less control over upward light that causes glare, and for that reason has been largely rejected outside the US. In addition, the American system makes it difficult to create markedly different low and high beam light distributions. The high beam is usually a rough copy of the low beam, shifted slightly upward and leftward. The European system traditionally produced low beams containing less overall light, because only 60% of the reflector's surface area is used to create the low beam. However, low beam focus and glare control are easier to achieve. In addition, the lower 40% of the reflector and lens are reserved for high beam formation, which facilitates the optimization of both low and high beams.
Recent developments
Complex-reflector technology in combination with new bulb designs such as H13 is enabling the creation of European-type low and high beam patterns without the use of a Graves Shield, while the 1992 US approval of the H4 bulb has made traditionally European 60% / 40% optical area divisions for low and high beam common in the US. H13, H-13 or H13 may refer to H-13 (Michigan county highway Highway H13 (Ukraine, a road in Ukraine Therefore, the difference in active optical area and overall beam light content no longer necessarily exists between US and ECE beams. Dual-beam HID headlamps employing reflector technology have been made using adaptations of both techniques.
Projector (polyellipsoidal) lamps
 Projector optics, side view |  Projector headlamps |
In this system a filament is located at one focus of an ellipsoidal reflector and has a condenser lens at the front of the lamp. In Geometrical optics, a focus, also called an image point, is the point where Light rays originating from a point on the object converge. In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging A shade is located at the image plane, between the reflector and lens, and the projection of the top edge of this shade provides the low-beam cutoff. The shape of the shade edge, and its exact position in the optical system, determines the shape and sharpness of the cutoff. [11] The shade may have a solenoid actuated pivot to provide both low and high beam, or it may be stationary in which case separate high-beam lamps are required. A solenoid is a three-dimensional Coil. In Physics, the term solenoid refers to a loop of wire often wrapped around a Metallic core which The condenser lens may have slight fresnels or other surface treatments to reduce cutoff sharpness. Recent condenser lenses incorporate optical features specifically designed to direct some light upward towards the locations of retroreflective overhead road signs. A retroreflector (sometimes called a retroflector) is a device or surface that reflects light back to its source with a minimum scattering of light
Hella introduced its "projector beam" optics for acetylene headlamps in 1911, but following the electrification of vehicle lighting, this optical technology wasn't used for many decades. Hella KGaA Hueck & Co is a German company that manufactures Automotive lighting devices such as Headlamps signal lamps and the Electronics Acetylene ( IUPAC name ethyne), C2H2 is a Hydrocarbon belonging to the group of Alkynes It is the simplest of all alkynes The first modern polyellipsoidal automotive lamp was the Super-Lite, an auxiliary headlamp produced in a joint venture between Chrysler Corporation and Sylvania and optionally installed in 1969 and 1970 full-size Dodge automobiles. Chrysler LLC is an American Automobile manufacturer that has been producing Automobiles since 1925 Dodge is a United States -based brand of Automobiles Sport utility vehicles and Trucks manufactured and marketed by Chrysler LLC It used an 85 watt transverse-filament tungsten-halogen bulb and was intended as a mid-beam, to extend the reach of the low beams during turnpike travel when low beams alone were inadequate but high beams would produce excessive glare. [12]
Projector main headlamps first appeared in 1981 on the Audi Quartz, the Audi Quattro-based concept car designed by Pininfarina for Geneva Auto Salon. Developed more or less simultaneously in Germany by Hella and in France by Cibié, the projector low beam permitted accurate beam focus and a much smaller-diameter optical package, though a much deeper one, for any given beam output. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. This article is about the country For a topic outline on this subject see List of basic France topics. The version of the 1986 BMW 7 Series sold outside North America was the first volume-production auto to use polyellipsoidal low beam headlamps. The BMW 7 Series is a line of Full-size Luxury vehicles produced by the German automaker BMW.
Light sources
Tungsten light sources
The first electric headlamp light source was the tungsten filament, operating in a vacuum or inert-gas atmosphere inside the headlamp bulb or sealed beam. Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 An electrical filament is a thread of Metal, usually Tungsten, which is used to convert Electricity into light in Incandescent light bulbs (as developed This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general Compared to newer-technology light sources, tungsten filaments give off small amounts of light relative to the power they consume. Also, during normal operation of such lamps, tungsten boils off the surface of the filament and condenses on the bulb glass, blackening it. This reduces the light output of the filament and blocks some of the light that would pass through an unblackened bulb glass. For these reasons, plain tungsten filaments are all but obsolete in automotive headlamp service.
Tungsten-halogen light sources
Halogen technology (also "quartz-halogen", "quartz-iodine", "iodine", "iode") makes tungsten filaments more efficacious producers of light—more lumens out per watt in—and Europeans chose to use this extra efficacy to provide drivers with more light than was available from nonhalogen filaments at the same power consumption. A halogen lamp is an Incandescent lamp in which a Tungsten filament is sealed into a compact transparent envelope filled with an inert gas plus a small amount of Incandescence is the emission of Light (visible Electromagnetic radiation) from a hot body due to its temperature Unlike the European approach which emphasized increased light output, most U. S. low beam halogens were low current versions of their nonhalogen counterparts, producing the same amount of light with less power. A slight theoretical fuel economy benefit and reduced vehicle construction cost through reduced wire and switch ratings were the claimed benefits. There was an improvement in seeing distance with U. S. halogen high beams, which were permitted for the first time to produce 150,000 candela (cd) per vehicle, double the nonhalogen limit of 75,000 cd but still well shy of the international European limit of 225,000 cd. The candela (kanˈdɛlə /-ˈdiːlə/ symbol cd) is the SI base unit of Luminous intensity; that is power emitted by a light source in a particular After replaceable halogen bulbs were permitted in U. S. headlamps in 1983, development of U. S. bulbs continued to favour long bulb life and low power consumption, while European designs continued to prioritize optical precision and maximum output.
The first halogen bulb for vehicle use, the H1, was introduced in 1962 by a consortium of European bulb and headlamp makers. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions This bulb has a single axial filament that consumes 55 watts at 12. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. 0 volts, and produces 1550 lumens ±15% when operated at 13. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. 2 V. H2 (55 W @ 12. 0 V, 1820 lm @ 13. 2 V) followed in 1964, and the transverse-filament H3 (55 W @ 12. 0 V, 1450 lm ±15%) in 1966. H1 still sees wide use in low beams, high beams and auxiliary foglamp and driving lamps, as does H3. Beam may refer to Beam (structure, a construction element Beam (nautical, the most extreme width (or breadth of a nautical vessel or a The H2 does not see wide use any more because it requires an intricate bulb holder interface to the lamp, has a short life and is difficult to handle. For those reasons, H2 was withdrawn from ECE Regulation 37 for use in new lamp designs (though H2 bulbs are still manufactured for replacement purposes in existing lamps). The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE The use of H1 and H3 bulbs was legalized in the United States in 1997. More recent single filament bulb designs include the H7 (55 W @ 12. 0 V, 1500 lm ±10% @ 13. 2 V), H8 (35 W @ 12. 0 V, 800 lm ±15% @ 13. 2 V), H9 (65 W @ 12. 0 V, 2100 lm ±10% @ 13. 2 V), and H11 (55 W @ 12. 0 V, 1350 lm ±10% @ 13. 2 V). 24-volt versions of many bulb types are available for use in trucks, buses, and other commercial and military vehicles. This article is about the semi-truck For the North American use of the word see Pickup truck. A military is an Organization authorized by its Nation to use force usually including use of Weapons in defending its Country (or by attacking
The first dual-filament halogen bulb (to produce a low and a high beam with only one bulb), the H4, was released in 1971. The U. S. prohibited halogen headlamps until 1978, when halogen sealed beams were released. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of To this day, the H4 is still not legal for automotive use in the United States. Instead, the Americans created their own very similar standard (HB2/9003). The primary differences are that the HB2 sets more strict requirements on filament positioning, and that the HB2 are required to meet the lower maximum output standards set forth by the United States government.
The first U. S. halogen headlamp bulb, introduced in 1983, was the 9004/HB1. It is a 12. 8-volt, transverse dual-filament design that produces 700 lumens on low beam and 1200 lumens on high beam. The 9004 is rated for 65 watts (high beam) and 45 watts (low beam) at 12. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. 8 volts. Other U. S. approved halogen bulbs include the 9005/HB3 (65 W, 12. Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions 8 V), 9006/HB4 (55 W, 12. 8 V), and 9007/HB5 (65/55 watts, 12. 8 V).
Halogen Infrared Reflective light sources
A further development of the tungsten-halogen bulb has a dichroic coating that passes visible light and reflects infrared radiation. Dichroic redirects here For the filter see Dichroic filter. For the glass see Dichroic glass. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of The glass in such a bulb is spherical, rather than tubular. "Globose" redirects here See also Globose nucleus. A sphere (from Greek σφαίρα - sphaira, "globe The reflected infrared radiation strikes the filament located at the centre of the sphere, heating the filament to a degree greater than occurs by passing an electric current through the filament. The filament thus superheated emits more light, without an increase in power consumption or a decrease in lifespan.
HID light sources (xenon and bi-xenon)
HID stands for high-intensity discharge, the technical term for the electric arc that produces the light. A High-intensity discharge (HID lamp is a type of electrical lamp which produces light by means of an electric arc between Tungsten Electrodes An electric arc is an Electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive Automotive HID lamps are commonly called 'xenon headlamps', although they are actually metal halide lamps that contain xenon gas. Metal halide lamps, a member of the High-intensity discharge (HID family of lamps produce high light output for their size making them a compact powerful and efficient Xenon (ˈzɛnɒn or) is a Chemical element represented by the symbol Xe. The xenon gas allows the lamps to produce minimally adequate amounts of light immediately upon startup and speed the warmup time. If argon were used instead, as is commonly done in street and other stationary metal halide lamp applications, it would take several minutes for the lamps to reach their full output. This article pertains to the chemical element For other uses see Argon (disambiguation. HID headlamps use a small, purpose-designed burner which produces more light than ordinary tungsten and tungsten-halogen bulbs. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general The light from HID headlamps has a distinct bluish tint when compared with tungsten-filament headlamps. The high intensity of the arc comes from metallic salts that are vapourised within the arc chamber.
HID headlamp bulbs produce between 2,800 and 3,500 lumens from between 35 and 38 watts of electrical power, while halogen filament headlamp bulbs produce between 700 and 2,100 lumens from between 40 and 72 watts at 12. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. 8 V [13][14][15]. Because of the increased amounts of light available from HID bulbs, HID headlamps producing a given beam pattern can be made smaller than halogen headlamps producing a comparable beam pattern. Alternatively, the larger size can be retained, in which case the xenon headlamp can produce a more robust beam pattern.
HID headlamp bulbs do not run on low-voltage DC current, so they require a ballast with either an internal or external ignitor. An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric The ballast controls the current to the bulb. When the headlamps are switched on, the ignitor provides rapidly pulsed current at several thousand volts to initiate the arc between the electrodes within the bulb. Once the arc is started, its heat begins to vapourise the metallic salts within the arc chamber, and the ballast gradually transitions from startup operation to arc-maintenance operation. Once the arc is completely stabilised, the ballast provides 85 V in conventional D1 and D2 systems, or 42 V with mercury-free D3 and D4 systems.
The correlated color temperature of HID headlamp bulbs, at between 4100 K and 4400 K, is often described in marketing literature as being closer to the 6500 K of sunlight compared with tungsten-halogen bulbs at 3000 K to 3550 K. Color temperature is a characteristic of Visible light that has important applications in lighting photography videography publishing and other fields Nevertheless, HID headlamps' light output is not similar to daylight. The spectral power distribution (SPD) of an automotive HID headlamp is discontinuous, while the SPD of a filament lamp, like that of the sun, is a continuous curve. In Statistical signal processing and Physics, the spectral density, power spectral density ( PSD) or energy spectral density ( Moreover, the color rendering index (CRI) of tungsten-halogen headlamps (≥0. The CIE color rendering index ( CRI) (or colour rendering index in British-style spelling sometimes called color rendition index) is a quantitative 98) is much closer than that of HID headlamps (~0. 75) to standardised sunlight (1. 00). Studies have shown no significant safety effect of this degree of CRI variation in headlighting.
The arc within an HID headlamp bulb generates considerable short-wave ultraviolet (UV) light, but none of it escapes the bulb. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays A UV-absorbing hard glass shield is incorporated around the bulb's arc tube. This is important to prevent degradation of UV-sensitive components and materials in headlamps, such as polycarbonate lenses and reflector hardcoats. The lamps do emit considerable near-UV light.
European vehicles equipped with HID headlamps are required by ECE regulation 48 also to be equipped with headlamp lens cleaning systems and automatic beam levelling control. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE Both of these measures are intended to reduce the tendency for high-output headlamps to cause high levels of glare to other road users.
HID headlamp bulb types D1R, D1S, D2R, D2S and 9500 contain the toxic heavy metal mercury. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum The disposal of mercury-containing vehicle parts is increasingly regulated throughout the world, for example under US EPA regulations. Newer HID bulb designs D3R, D3S, D4R, and D4S contain no mercury, but are not electrically or physically compatible with headlamps designed for previous bulb types.
The arc light source in an HID headlamp is fundamentally different from the filament light source used in tungsten/halogen headlamps. For that reason, HID-specific optics are used to collect and distribute the light. Installing HID bulbs in headlamps designed to take filament bulbs results in improperly-focused beam patterns and excessive glare, and is therefore illegal in almost all countries. [16]
LED light sources
Automotive headlamp applications using LEDs have been undergoing very active development since 2004[17][18]. The first series-production LED headlamps are factory-installed on the 2008 Lexus LS 600h / LS 600h L (low beam, front position light and sidemarker only; high beam and turnsignal are filament based. The Lexus LS is a Full-size luxury sedan that serves as the flagship of Lexus, the luxury division of Toyota. The headlamp is supplied by Koito), and on the version of the 2008 Audi R8 sports car sold outside North America supplied by Automotive Lighting. The Audi R8 is a mid-engined Sports car introduced by the German automaker Audi in 2007 priced at 113150 The LED headlamp supplied by Hella for the 2009 Escalade Platinum is the first U. S. market headlamp with both a LED low and high beam. Present designs give performance between halogen and HID headlamps, with system power consumption slightly higher than halogen headlamps. These lamps currently require large packaging and a large number of the most powerful LED emitters available. As LED technology continues to evolve, the performance of LED headlamps is predicted to improve to approach, meet, and perhaps one day surpass that of HID headlamps. [19]
The limiting factors with LED headlamps presently include high system expense, regulatory delays and uncertainty, glare concerns related to the output spectrum of white LEDs, and logistical issues created by LED operating characteristics. A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. LEDs are commonly considered to be low-heat devices due to the public's familiarity with small, low-output LEDs used for electronic control panels and other applications requiring only modest amounts of light. However, LEDs actually produce a significant amount of heat per unit of light output. Rather than being emitted together with the light as is the case with conventional light sources, an LED's heat is produced at the rear of the emitters. The cumulative heat of numerous high-output LED emitters operating for prolonged periods poses thermal-management challenges for plastic headlamp housings. In addition, this heat buildup materially reduces the light output of the emitters themselves. LEDs are quite temperature sensitive, with many types producing at 30 °C (85 °F) only 60% of the rated light output they produce at an emitter junction temperature 16 °C (60 °F). Prolonged operation above the maximum junction temperature will permanently degrade the LED emitter and ultimately shorten the device's life. The need to keep LED junction temperates low at high power levels always requires additional thermal management measures such as heatsinks and exhaust fans which are typically quite expensive.
Additional facets of the thermal issues with LED headlamps reveal themselves in cold ambient temperatures. Many types of LEDs produce at -12 °C (10 °F) up to 160% of their 16 °C (60 °F) rated output. The temperature-dependency of LED's light output creates serious challenges for the engineering and regulation of automotive lighting devices, which are in some cases required to produce intensities within a range smaller than the variation in LED output with temperatures normally experienced in automotive service.
Cold weather also brings another thermal-management conundrum: Not only must heat be removed from the rear of the headlamp so that the housing does not deform or melt and the emitters' output does not drop excessively, but heat must in addition be effectively applied to thaw snow and ice from the front lenses, which are not heated by the comparatively small amount of infared radiation emitted forward with the light from LEDs.
LEDs are increasingly being adopted for signalling functions such as parking lamps, brake lamps and turn signals as well as daytime running lamps, as in those applications they offer significant advantages over filament bulbs with fewer engineering challenges than headlamps pose. A daytime running lamp ( DRL, also daylight running lamp or daytime running light) is a lighting device on the front of a roadgoing Motor
Dynamic Headlight Beam Control
Headlamp Levelling Control
In 1954, Cibié introduced an automatic headlamp leveling system linked to the vehicle's suspension system to keep the headlamps correctly aimed regardless of vehicle load. The first vehicle to be so equipped was the Panhard Dyna Z. The Panhard Dyna Z was a light weight motor car made by Panhard of France. Beginning in the 1970s, Germany and some other European countries began requiring remote-control headlamp levelling systems that permit the driver to lower the lamps' aim by means of a dashboard control lever or knob if the rear of the vehicle is weighted down with passengers or cargo, which would tend to raise the lamps' aim angle and create glare. Such systems typically use stepper motors at the headlamp and a rotary switch on the dash marked "0", "1", "2", "3" for different beam heights, "0" being the "normal" (and highest) position for when the car is lightly loaded. A stepper motor (or step motor) is a brushless, synchronous Electric Internationalized ECE Regulation 48, in force in most of the world outside North America, currently requires such systems on all vehicles. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE The regulation stipulates a more stringent version of this antiglare measure for vehicles equipped with headlamp bulbs producing more than 2,000 lumens, such as Xenon headlamps; such vehicles must be equipped with headlamp self-levelling systems that sense the vehicle's degree of squat due to cargo load and road inclination, and automatically adjust the headlamps' vertical aim to keep the beam correctly oriented without any action required by the driver.
Directional headlamps
These provide improved lighting for cornering. A corner is the place where two Lines of different dimensions meet at an Angle, and a convex corner of intersecting walls is generally thought to be the least beneficial Some automobiles have their headlamps connected to the steering mechanism so the lights will follow the movement of the front wheels. Steering is the term applied to the collection of components linkages etc Czech Tatra and 1920s Cadillacs were early implementer of such a technique, producing in the 1930s a vehicle with a central directional headlamp. The American 1948 Tucker Sedan was likewise equipped with a third central headlamp connected mechanically to the steering system. The 1948 Tucker Sedan or Tucker '48 Sedan (also nicknamed the Tucker Torpedo) was an advanced Automobile conceived by Preston Tucker and briefly The 1967 French Citroën DS and 1970 Citroën SM were equipped with an elaborate dynamic headlamp positioning system that adjusted the headlamps' horizontal and vertical positioning in response to inputs from the vehicle's steering and suspension systems, though US regulations required this system to be deleted from those models when sold in the USA. The Citroën DS (also known as Déesse, or Goddess, after the punning initials in French is an Executive car that was produced by The Citroën SM was a high performance Coupé produced by the French manufacturer Citroën between 1970 and 1975 Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States.
Advanced Front-lighting System (AFS)
There has been a recent resurgence in interest in the idea of moving or optimizing the headlight beam in response not only to vehicular steering and suspension dynamics, but also to ambient weather and visibility conditions, vehicle speed, and road curvature and contour. A task force composed primarily of European automakers, lighting companies and regulators began working to develop design and performance specifications for what is known as Advanced Front-lighting Systems, commonly "AFS". Manufacturers such as Audi, Lexus and Vauxhall have released vehicles equipped with AFS since 2002. AUDI AG, ( Xetra: NSU commonly known as Audi (aˈʊdi is a German Automobile manufacturer which produces Audi branded cars with headquarters is the Luxury vehicle division of Japanese automaker Toyota Motor Corporation. Vauxhall Motors is a British automobile company It is a subsidiary of General Motors Corporation (GM and is part of GM Europe. Rather than the mechanical linkages employed in earlier directional-headlamp systems, AFS relies on electronic sensors, transducers and actuators. A transducer is a device usually electrical, electronic, Electro-mechanical, Electromagnetic, Photonic, or Photovoltaic Other AFS techniques include special auxiliary optical systems within a vehicle's headlamp housings. These auxiliary systems may be switched on and off as the vehicle and operating conditions call for light or darkness at the angles covered by the beam the auxiliary optics produce. Development is underway of AFS systems that use GPS signals to anticipate changes in road curvature. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth
Care
Headlamp systems require periodic maintenance. Sealed beam headlamps are modular; when the filament burns out, the entire sealed beam is replaced. A sealed beam is a type of lamp that includes a Reflector and filament as a single assembly over which a front cover ( lens) usually of An electrical filament is a thread of Metal, usually Tungsten, which is used to convert Electricity into light in Incandescent light bulbs (as developed Most vehicles in North America made since the late 1980s use headlamp lens-reflector assemblies that are considered a part of the car, and just the bulb is replaced when it fails. Manufacturers vary the means by which the bulb is accessed and replaced. Headlamp aim must be properly checked and adjusted frequently, for misaimed lamps are dangerous and ineffective[10]
Over time, the headlamp lens can deteriorate. It can become pitted due to abrasion of road sand and pebbles, and can crack, admitting water into the headlamp. "Plastic" (polycarbonate) lenses can become cloudy and discolored. This is due to oxidation of the painted-on lens hardcoat by ultraviolet light from the sun and the headlamp bulbs. If it is minor, it can be polished out using a reputable brand of a car polish that is intended for restoring the shine to chalked paint. In more advanced stages, the deterioration extends through the actual plastic material, rendering the headlamp useless and necessitating complete replacement. Sanding or aggressively polishing the lenses can buy a small amount of time, but doing so removes the protective coating from the lens, which when so stripped will deteriorate faster and more severely.
The reflector, made out of vaporized aluminum deposited in an extremely thin on a metal, glass or plastic substrate, can become oxidized or burnt and lose its specular reflective properties. Substrate is a term used in Materials science to describe the base material on which processing is conducted to produce new film or layers of material such as deposited coatings This can happen if water enters the headlamp, if bulbs of higher wattage than specified are used, or simply with age and use. If the reflector when viewed by itself is not mirror-perfect, the headlamp should be replaced, for reflectors cannot effectively be restored.
Lens cleaners
Dirt buildup on headlamp lenses increases glare to other road users, even at levels too low to reduce seeing performance significantly for the driver. The fifth generation Volkswagen Golf Mk5 (VW Typ 1K) built on the Volkswagen Group A5 (PQ35 platform was unveiled at the Frankfurt Motor Show in Therefore, headlamp lens cleaners are required by ECE Regulation 48 on vehicles equipped with low-beam headlamps using light sources that have a reference luminous flux of 2,000 lumens or more. The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE This includes all HID headlamps and some high-power halogen units. Some cars have lens cleaners fitted as standard or available as optional equipment even where the headlamp specifications and/or prevailing technical regulations do not require them. North America, for example, does not use ECE regulations, and FMVSS 108 does not require lens cleaners on any headlamps, though they are permitted. Federal Motor Vehicle Safety Standard 108 (FMVSS 108 regulates all automotive lighting signalling and reflective devices in the United States. Lens cleaning systems come in two main varieties: a small motor-driven wiper blade or brush conceptually similar to those used on the windshield of the car, or a fixed or pop-up high-pressure sprayer which cleans the lenses with a spray of windshield washer fluid.
See also
- Automotive lighting
- Hidden headlamps
- Fog
- World Forum for Harmonization of Vehicle Regulations
- Non-glaring headlamp
References
- ^ Georgano, G. Hidden headlamps are an automotive styling feature that conceals an Automobile 's Headlamps when they are not in use Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe (UNECE A non-glaring headlamp is an Invention by Assist Prof Dr Turhan Alçelik N. Cars: Early and Vintage, 1886-1930. (London: Grange-Universal, 1985).
- ^ ECE R112PDF (313 KiB)
- ^ ECE R98PDF (843 KiB)
- ^ FMVSS No. 108PDF (2. A kibibyte (a contraction of ki lo bi nary byte) is a unit of Information or Computer storage, established by the International A kibibyte (a contraction of ki lo bi nary byte) is a unit of Information or Computer storage, established by the International 00 MiB)
- ^ Rumar, Kåre (2000), Relative merits of the U.S. and ECE high-beam maximum intensities and of two- and four-headlamp systems, UMTRI, <http://hdl.handle.net/2027.42/49438>
- ^ Headlamp traffic-handedness
- ^ a b "Where Does The Glare Come From?" (NHTSA glare response + white paper on headlamp performance, glare, and regulation)PDF (463 KiB)
- ^ Grueninger, Wes (5 March 2008), “Prometheus, Bound: The Difference Between American and European Car Lighting”, Motive Magazine, <http://www.motivemag.com/pub/feature/tech/Motive_Tech_The_Difference_Between_US_and_European_Lights.shtml>
- ^ Headlamp industry veteran engineer's chronology & commentary on headlamp performance, glare & regulationPDF (3. A mebibyte (a contraction of me ga bi nary byte) is a unit of Information or Computer storage, abbreviated MiB. A kibibyte (a contraction of ki lo bi nary byte) is a unit of Information or Computer storage, established by the International 02 MiB)
- ^ a b Headlamp aiming specifications & procedures
- ^ a b c Headlamp Optical Systems Illustrated, Explained & Compared
- ^ Chrysler/Sylvania Super-Lite turnpike beamPDF (8. A mebibyte (a contraction of me ga bi nary byte) is a unit of Information or Computer storage, abbreviated MiB. 60 MiB)
- ^ ECE Regulation 37 for motor vehicle filament bulbsPDF (1. A mebibyte (a contraction of me ga bi nary byte) is a unit of Information or Computer storage, abbreviated MiB. 78 MiB)
- ^ ECE Regulation 99 for motor vehicle HID bulbsPDF (268 KiB)
- ^ 49CFR564 Replaceable Bulb Headlamp Light Source List
- ^ HID kit retrofitment into halogen lamps — technical & legal considerations
- ^ VW Golf V LED headlamp study and prototype as of 2005
- ^ New-generation LED headlamp prototype with performance equal to HID
- ^ Production LED headlamp technology & design as of 2007
Dictionary
headlamp
-noun
- An individual headlight, particularly of a motor vehicle.
- A flashlight worn on head.
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