Through The Past Darkly - Horrible Headlight History

[Junkman]

Looking forward the the Yellow Headlghts bit

I saw a modern Eurobox the other day sporting Yellow Light wayy after the 93 compulsary ending but I guess it was just Pineapple Scene

Incidentally I remember during the 80's everybody buying the yellow clip on's for going to France but would take them off the second they rolled off the boat like they were going to be flogged in public if they didnt

Whats the law here regarding yellow headlights ?

Your Renault would look the part with them

Well, dah.




The legal situation is European, as usual. Some countries never allowed yellow headlights, some did, only in France they were mandatory. The EEC regulation says that cars fitted with yellow headlights when new can retain them wherever it was legal at the time, which means you can use them on any pre 1993 car registered in a country where they were allowed back then. The UK is one of these countries. They always were illegal in the entire German speaking area (D/A/CH), Scandinavia, and practically the entire former Eastern Block. However, yellow driving or fog lights are legal to this day, pretty much world wide.

Having said that, I want to meet the copper who dings someone for having yellow lights on his classic car.

[Junkman]

9. 1971-1980

While the Europeans pretty much stuck to their H1 - H4 lighting standards throughout this decade, the Americans tinkered with their headlights quite a bit.

Remember, at the time only two headlamps sizes were legal there. Either two round 7 inch sealed beams (since 1941), or four round 5 3/4 inch sealed beams (since 1957).
Detroit's stylists found this too restrictive and placed a petition, which was approved by the NHTSA in 1974, so that from model year 1976 (i.e. autumn 1975), new cars could be fitted with four rectangular sealed beam headlamps sized 4 inches by 6 1/2 inches, again, two of which were specifically for main beam, two for combined dipped and main beam courtesy of two filaments. Two years later another headlamp configuration became legal, comprising two rectangular sealed beams sized 142 mm by 200 mm (yes, not inches) with two filaments for dipped and main beam.
This means that whenever a headlight needs to be replaced on your 1940 to 1984 yank tank, it can only be one of six different types. Needless to say that even your local convenience store had these on the shelf.

Then, in 1978, the NHTSA increased the maximum allowed headlamp intensity per vehicle by simply doubling it from from 75,000 cd to 150,000 cd, which finally made filling sealed beams with halogen feasible. Of course not the entire headlight was filled, they were internally fitted with a glass bubble over the filaments and this was filled with halogen. Since a hermetic seal between the reflector and the glass lens was thus no longer required, they were no longer melted together, but adhesive bonded instead. This led to another new development, namely for the first time ever plastic lenses were used and for a while all glass adhesive bonded halogen sealed beams were manufactured alongside sealed beams with plastic lenses, and even plastic lenses and reflectors. For the plastic lamps, materials and coatings were developed to provide adequate abrasion resistance, and the plastic materials vastly decreased the susceptibility for breakage when the lights were hit by stones.

All the while, Europe at the time had a much higher percentage of headlamps with halogen light sources than the U.S. The overwhelming majority of European headlamps used replaceable bulbs, because only some European countries allowed sealed beams at all and even in those they weren't commonly fitted. Sealed beams used in Europe had to meet the ECE beam pattern requirements, so U.S. sealed beams were not legal anywhere. However, European spec replacement headlights for the standard U.S. sealed beams were and are readily available, in left and right dip flavours, to enable owners of American cars using them on Europe's roads. Even some European and many Japanese cars had them as standard equipment. However, most European cars were fitted with "architectural" headlights specific to the make and model already since the early Sixties.

[Junkman]

10. 1981-1990

In 1983 the NHTSA, again responding to a petition, approved the use of headlamps fitted with a standardised replaceable halogen bulb (9004) in the U.S. For the first time ever "architectural" headlamps could be fitted to new American cars for the 1984 model year. Practically immediately most American cars were designed with these new style headlamps with few exceptions. Plastic lenses and housings were the materials of choice from the onset, because they provided improved headlamp performance and increased styling flexibility. Nevertheless, further sealed beam sizes (e.g., 92 mm by 150 mm in 1986) were introduced, as well as additional halogen replaceable bulbs (e.g. 149005 and 9006 in 1987), which finally provided Americans stylists with sufficient flexibility to design practically any shape and form of headlamp assembly and legally install it on domestic market vehicles.

At the same time research and development was done on HID (high intensity discharge) lighting systems all over the world. Again, this wasn't new technology, but it had to be adapted for automotive use. In particular startup and quick restrike (that's switching between main and dipped beams) times had to be brought to within acceptable levels.

Although the early lighting literature indicates that attempts were made even back then to use something other than a parabolic reflector, most headlamps from the very beginning of automotive lighting employed such a reflector to collect the light from the source. By the early Eighties, European engineers began to experiment with segmented reflectors, although the basic surfaces were still parabolic. Their light source of choice was still the trusty H4 bulb, though. The 1983 Austin Maestro was the first vehicle equipped with Lucas-Carello's homofocal reflectors, which comprised parabolic sections of different focal length to improve the efficiency of light collection and distribution.

The next step was to develop multisegmented reflector surfaces, but this only became feasible with the emerging availability of CAD programs for optical applications. Smooth computer generated surfaces could now be designed, with the goal to ultimately form the required beam pattern without any optics in the lens. The 1987 Dodge Monaco/Eagle Premier twins and the Citroën XM were the first commercially available cars with complex reflector shapes, but they still had faceted optic lenses. General Motors' Guide Lamp division in America had experimented with clear lens complex reflector lamps already in the early 1970s and achieved promising results, but the U.S. market 1990 Honda Accord was first car ever with clear lens multi reflector headlamps. These had been developed by Stanley in Japan.

Ellipsoidal surfaces for headlamp reflectors were also first attempted early in the history of headlighting. I found an article about it issued by the Department of Commerce in 1925 and obviously it wasn't a new thing even then. In 1985, polyellipsoid headlamps (also called projector lamps) were developed in Europe and first installed as production headlights in a Neoplan city bus in Germany. Soon many other types of vehicles were equipped with this type of headlamp assembly. The advantages are a smaller headlamp vertical height, more uniformity in the beam pattern, and the ability to make a sharper cutoff, or gradient, which allows more accurate visual headlamp aim. They are particularly well suited for motorcycles and became almost universal on those for a while.

[Junkman]

10. 1991 - today

I realise that this is quite a long time, but not all that much has happened in terms of headlight development. The emphasis was more on global harmonisation, but although there are a lot of committees with a lot of undoubtedly very well paid people working on it, no common agreement has been reached as of now.

In the U.S., a new sealed beam headlamp headlamp (55 mm by 135 mm) was approved in 1991. It turned out to be too small for the existing field mechanical aimers, which were still a legal requirement. Consequently, a new method of mechanical aiming had to be developed. By installing a vehicle headlamp aiming device (VHAD) on each headlamp of the car, mechanical aim could still be accomplished (this is for real!). The VHAD incorporated a level bubble for vertical aim, similar to the one already on the field mechanical aimers. For horizontal aim, the VHAD incorporated an indicator and a reference mark on the fixed vehicle structure, to replace the mirrors used on the field mechanical aimers. However, with VHADs, headlamps no longer required aiming tips on the lenses. VHADs were first installed in 1991 on the 55 mm by 135 mm headlamps, but later also on other types of headlamps.

At the same time, HID low beam headlamps were first installed on production vehicles in Europe, which thus now had the undisputed lead in headlight technology for the first time in history. Compared with tungsten/halogen headlamps, HIDs provide longer life, increased light source lumens, higher intensity beam patterns, increased color temperature of the light source, and greater durability of the light source. These advantages, however, are offset by a drastic increase of the cost. Within the next few years an increasing number of car models was fitted with HID dipped beam headlamps in Europe, Japan, and the U.S. Europe created new regulations for HID light sources and headlamps using HID light sources (ECE R98 and ECE R99). FMVSS 108 now contained several alternative dipped beam headlamp photometric specifications depending on the light source and the type of headlamp system. One of the most commonly used specifications in the 1990s is shown here:

Fig6.png (21.83 KiB) Viewed 5866 times

Mechanical aim, in one form or another, was the only method recognized by the U.S. government in FMVSS 108. Because of the many recent changes in the U.S. beam pattern, and also to harmonize the regulations with the rest of the world, the NHTSA began a regulatory negotiation process with several representatives of different companies and organizations associated with automotive lighting, in 1995. The result was a rule change (NHTSA, 1997) to allow visual/optical aim for headlamps in the U.S. that meet a certain minimum vertical gradient of the beam pattern. Now the beam pattern itself could be accurately positioned in the aiming process. This change harmonized the U.S. regulations with the rest of the world for the first time since 1954, when they decided to veer from the 1952 GTB agreement. As a result one common aiming method can now be used on all headlamps designed to meet certain specified requirements. A new beam pattern, with wider spreadlight and some changes in other test points, was also included in this rule change.

In 1990, the Group Rapporteurs Eclairage (GRE), an international group of government regulators with far reaching responsibility for lighting, yet again asked the GTB to study and recommend one harmonized worldwide headlamp beam pattern (it was around this time that I finally left the automotive field to pursue a career* in a saner** industry). Inevitably, the GTB's Coordinating Committee was established for this purpose, consisting of the chairmen of several international lighting committees. After determining a program of work, yet another comprehensive research study was commissioned to provide guidance in the harmonization process. This study considered expert opinion, current practice, and research evidence concerning visibility and glare as if these were anything hitherto unknown. It recommended four test points that should be made common throughout the world, as a first step towards a fully harmonized beam pattern. With slight modifications, these four test points were recommended by the GTB to the GRE.

Fig7.png (16.73 KiB) Viewed 5866 times

Starting with these four test points, the rest of the beam pattern was established by the GTB's Coordinating Committee to provide spread light, foreground limits, adequate overhead sign light, additional controls on glare, veiling glare limits, and gradient definition. To be fair, within the GTB considerable progress has been made, but, you guessed it, the previously mentioned differences in priorities between the U.S. and Europe concerning glare and seeing light still exist. Changes in the beam pattern resulted in improved seeing light and wider spread light and sufficient illumination on signs is retained, arguably without causing undo glare for oncoming traffic, and gradient values are specified that allow for relatively accurate visual/optical aim of the beam pattern.

Although agreements have been obtained on almost all aspects of the low beam pattern, resolution in some areas is still needed before a recommendation can formally be submitted by the GTB to the GRE. These most recent attempts in the GRE were initiated by Japan via the JASIC (Japan Automobile Standards Internationalization Center). The biggest differences in headlamp beam patterns exist between the U.S. and Europe, though. Japan has used an only slightly modified U.S. beam pattern inverted for driving on the left all along and only recently accepted European approved headlamps for the U.K. Japan has also indicated they will sign the United Nations “umbrella” document (1958 Agreement) for all ECE lighting regulations and will begin to enforce the ECE Regulations. Japan has also written the GTB's four common test points into their headlamp standard.

[Junkman]

11. Conclusions

From candles to HID, there have been tremendous changes in less than hundred years when it comes to light sources for vehicle headlamp systems. Metal and glass have given way to plastics. Headlamp designs have long since been integrated into the vehicle styled surfaces, whereas before headlamps were added on and looked every bit of an add on. The visual headlamp aiming of a hundred years ago has evolved to more accurate visual/optical aiming today with the latest beam patterns. Will there be more changes? Of course. Light sources will continue to change, so will materials used. Beam pattern requirements will continue to be a compromise between providing sufficient light for the driver and limiting the light in the opposing driver’s eyes. Adaptive front lighting systems will be capable of customising beam patterns for moment to moment changes in the road, driving, and weather conditions. But despite vehicle manufacturers and lighting manufacturers become ever more globalised, there will never be a world wide harmonised beam pattern, no matter how many committees waste their time on even trying.

[brandersnatch]

Fascinating stuff. Thanks for taking the time.

[Junkman]

12. References and further reading

Anonymous (1956) Automotive lighting 1906-1956. Illuminating Engineering, 51, 128-132. [Although the author is not listed, personal communications indicate that this article was written by V. Roper of General Electric.]

Banta, J. (1940) The story of headlights. Guide Light [Company newsletter of Guide Lamp Division, General Motors Corporation], 7, 5-9.

Carlson, R.E. (1929) The incandescent lamp for automotive lighting (SAE Technical Paper Series No. 290048). Warrendale, PA: Society of Automotive Engineers. Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 415-419).

Clark, E.L. (1916) Automobile lighting from the lighting viewpoint (SAE Technical Paper Series No.160007). Warrendale, PA: Society of Automotive Engineers.

deBoer, J.B. (1955) A ‘duplo’ headlight with asymmetric passing beam. Light and Lighting, 48,137-141.

deBoer, J.B. (1956) Progress in automobile lighting as a result of international visibility tests. Road Safety and Traffic Review, Winter, 18-23.

Department of Commerce (1925) Motor-vehicle headlighting (Circular of the Bureau of Standards No. 276) Washington, D.C. U.S. Government Printing Office.

Devaux, P. (1970) State-of-the-art signaling and lighting (SAE Technical Paper Series No. 700386). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 331-356).

Devine, A.W. (1921) Motor vehicle headlight in Massachusetts. Transactions of the Illuminating Engineering Society, 16, 507-518.

Drach, J. (1993) Automobilia, Automobilteile und Zubehör von 1886 bis 1976, Band II. Stuttgart, Germany, Robert Bosch GmbH.

Ehrhardt, R.A. (1979) Halogen sealed beam headlamps (SAE Technical Paper Series No. 790200). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 219-229).

Ehrhardt, R.A. (1992) The first eighty years of GE automotive lighting (unpublished manuscript).

GRE (Group Rapporteurs Eclairage) (1995) Harmonized passing beam pattern (TRANS/WP.29/GRE/R.210/Rev.1.Add.1), Brussels, Economic Commission for Europe.

Grondahl, L.O. (1921) A focus-indicator for headlights. Transactions of the Illuminating Engineering Society, 16, 164-172.

Fratty, H., Dorleans, G., and Schumacher, T.W. (1987) Improvements in low beam lighting achieved by complex surface reflectors (SAE Technical Paper Series No. 870059).

Heppenheimer, T.A. (1998) The man who found the universe in a light bulb. American Heritage of Invention & Technology, 13, 28-40.

Huhn, W. and Hege, G. (1995) High intensity discharge headlamps (HID)—experience for morethan 3-1/2 years of commercial application of litronic headlamps (SAE Technical PaperSeries No. 950591).

Jehu, V.J. (1954) A comparison of yellow and white headlamp beams. Light and Lighting, 47,287-291.

Johnston, R. H. (1996) A history of automobile electrical systems. Automotive Engineering, 104 (9), 53-66.

Kazenmaier, A. (1956) International comparative experiments with the American and European automobile headlamp types. Deutsche Kraftfahrtforschung und Strassenverkehrstechnik, 94, 1-26.

Kebler, L. (1912) The requirements of automobile electric lighting systems. Transactions of The Society of Automobile Engineers, VII (Part II), 284-289.

Kettering, C.F. (1912). Some points in electric lighting for automobiles. Transactions of The Society of Automobile Engineers, VII (Part II), 232-236.

Lindae, G. (1985). Improvemens of low-beam pattern by use of polyellipsoid headlamps (PES) (SAE Technical Paper Series No. 850228).

Alsoin G.J., Gaudaen (1996) Motor vehicle lighting (pp. 159-173).

Magdsick, H.H. and Falge, R.N. (1921) Determination by various observers of desired road illumination from automobile headlamps. Transactions of the Illuminating Engineering Society, 16, 480-506.

Maurer, P.W. (1980) History of automotive lighting in Europe (SAE Technical Paper Series No.800339). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 211-218).

McMurtry, A.L. (1917) Head-lamp design and its effect upon glare reduction (SAE Technical PaperSeries No. 170024).

Meese, G.E. (1972) Vehicular lighting systems for two-lane rural highways. In, Workshop on highway visibility. Washington, D. C.: Highway Research Board.

Meese, G.E. (1983) History of lighting test development (SAE Technical Paper Series 830638). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 191-195).

Moore, R.L. (1958) Headlight design. Ergonomics, 2, 163-176.

NHTSA (National Highway Traffic Safety Administration) (1978) Federal Register (Final Rule), 43, 32416-32421.

NHTSA (National Highway Traffic Safety Administration) (1996) Federal Register (Notice of Proposed Rule making), 61, 36334-36346.

NHTSA (National Highway Traffic Safety Administration) (1997) Federal Register, Final Rule, 62, 10710-10730.

Nelson, J.H. (1954) Design and use of head-lamp meeting beams. Proceedings of the Institute ofMechanical Engineers, Auto Division, 100-117.

Neumann, R. (1994) Improved projector headlamps using HID (litronic) and incandescent bulbs (SAE Technical Paper Series No. 940636). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 15-22).

Office of the Federal Register (1997) FMVSS (Federal Motor Vehicle Standard) 108 (Lamps, reflective devices, and associated equipment). In 49 Code of Federal regulations (Part 571.109). Washington, D.C. U.S. Government Printing Office.

Oliver, R.C. (1980) Kerosene to halogen — a history of automotive headlighting (SAE TechnicalPaper Series No. 800525). Also in G.J.Gaudaen (1996) Motor vehicle lighting (pp. 197-203).

Olson, P.L. (1977) The relative merits of different low beam headlighting systems (Report No. UM-HSRI-77-55). Ann Arbor, The University of Michigan, Highway Safety Research Institute.

Replogle, J.B. (1917) Head-lamp glare — what is it? (SAE Technical Paper Series No. 170017) Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 471-485).

Roper, V.J. (1957) Four headlamps for better seeing. Traffic Engineering, 1, 171-175.

Rumar, K. (1997) Adaptive illumination systems for motor vehicles: towards a more intelligent headlighting system (Report No. UMTRI-97-7). Ann Arbor, The University of Michigan Transportation Research Institute.

Schreuder, D.A. (1976) White or yellow light for vehicle head-lamps? (Report 1976-2E). Voorburg, The Netherlands, Institute for Road Safety Research SWOV.

Schroeder, H. (1916) Electric bulbs for automobiles (SAE Technical Paper Series No. 160003). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 511-526).

Sharp, C.H. (1921) Present status of automobile headlighting regulation. Transactions of the Illuminating Engineering Society, 16, 469-479.

Sivak, M. and Flannagan, M.J. (1993) Partial harmonization of international standards for low-beam headlighting patterns (Report No. UMTRI-93-11). Ann Arbor, The University of Michigan Transportation Research Institute.

Sivak, M., Flannagan, M.J., Budnik, E.A., Flannagan, C.G., and Kojima, S. (1996) The locations of headlamps and driver eye positions in vehicles sold in the U.S.A. (Report No. UMTRI-96-36). Ann Arbor, The University of Michigan Transportation Research Institute.

SAE (Society of Automotive Engineers) (1926) SAE handbook. New York: Society of Automotive Engineers.

SAE (Society of Automotive Engineers) (1933) New headlighting specification for safe night driving. SAE Journal, 37-38.

SAE (Society of Automotive Engineers) (1945) SAE handbook. New York: Society of Automotive Engineers.

SAE (Society of Automotive Engineers) (1966) Sealed beam headlamp units for motor vehicles (SAE Standard J579a).

Spencer, C.W. (1984) Headlamp developments with DMC reflectors including homofocal arrangements (SAE Technical Paper Series No. 840041). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 175-189).

Spencer, C.W. and Manunta, G. (1987) High performance low profile headlamps (SAE TechnicalPaper Series No. 870060). Also in G.J. Gaudaen (1996) Motor vehicle lighting (pp. 131-142).

[Junkman]

I don't even know where to start regarding the yellow headlights, because there is such a vast array of urban legends and bullshit that need to be debunked.

I'm working on it.

[Junkman]

1. What is "selective yellow" light?

It is a particular kind of yellow light that was required from ALL road illumination lamps on vehicles in France.

Light containing a mix of all the colours - red, orange, yellow, green, blue, indigo, and violet. Removing the blue, indigo, and violet from white light results in selective yellow light.
It is not the same as the more orange colour called "yellow" or "amber" used for indicators.

The UNECE Regulations formally define selective yellow in terms of the CIE 1931 colour space as follows:

Selective yellow.png (13.17 KiB) Viewed 5841 times

The entirety of the basic selective yellow definition lies outside the gamut of the sRGB colour space. Such a pure yellow cannot be represented using RGB primaries, which means it is impossible to show it correctly on computer screens.

Selective yellow (desaturated approximation)

Colour coordinates:

Hex triplet #FFBA00
sRGBB (r, g, b) (255, 186, 0)
CMYKH (c, m, y, k) (0, 27, 100, 0)
HSV (h, s, v) (44°, 100%, 100%)

Source: CIECD

FFBA00.png (1.36 KiB) Viewed 5841 times

This colour swatch is a desaturated approximation, created by taking the centroid of the standard selective yellow definition at (0.502, 0.477) and moving it towards the D65 white point, until it meets the sRGB gamut triangle at (0.478, 0.458).

[Junkman]

2. Why and when did France require selective yellow light?

Forget the legend that it was a tactical decision at the urging of the military, to facilitate identification of the nationality of a vehicle at night during the war. There was practically no civilian traffic and French military vehicles were under German control anyway. Oddly, the Germans did not impose the German highway code during the occupation, so yellow lighting remained compulsory for French registered vehicles.
Another legend is that the French road pavement had peculiar reflective properties. Well, it didn't.
Some say it was market protectionism. Well, it wasn't.
An annoyingly persistent myth holds that yellow light enables you to see better in fog. This nonsense can be debunked by simple science.
The reason given by the yellow light being better in fog believers is that blue light scatters more, as evidenced by the sky being blue. The sky is indeed blue because of Rayleigh Scattering. Short wavelength light does indeed scatter more, but only in droplets and particles equal or smaller than the wavelength of the light, which is much smaller than the size of the droplets that make up fog. There is no Rayleigh Scattering happening to the light from a vehicle's front lamps, and whatever blue light those lamps might be producing does not get scattered by fog more than any other colours of light.

The fact is, that in late 1936 lawmakers in France put forth legislation requiring all road illumination lamps (headlamps, fog lamps, etc.) on all vehicles to emit selective yellow light.
This legislation was based on advice from the French Central Commission for Automobiles and Traffic, which in turn was based on experiments done by the French Academy of Sciences beginning in 1923. It concluded that selective yellow light is less glaring than white.
Here is the decree, published in the 5 November 1936 edition of the Journal Officiel de la Republique Française, the official journal of the French Republic, like The Gazette in the UK.

French_SY_Headlamp_Decree_Large.jpg (405.61 KiB) Viewed 5840 times

This decree translates as follows:

The Minister of Public Works, in view of the decree of 31 December 1922 laying down general rules on traffic and traffic regulations, as amended by the decrees of 2 September 1925, 21 August 1928, 5 October 1929, 19 January 1933, and 17 January and 1 October 1935, and in particular Article 24; with regard to the Ministerial Decree of 28 July 1923 and that of 10 October 1933 amending the decree in question and determining the conditions to be met by the provisions of automotive lighting; and with regard to the opinion of the Central Commission of Automobiles and Traffic dated 9 January 1936; on the proposal of the State Councillor Director General of Highways,

Be it enacted:

Article 1: All road illumination lamps mounted on a vehicle registered after 1 April 1937 shall produce selective yellow light and shall comply with an approved photometric standard. This provision shall apply to all motor vehicles as from 1 January 1939.

Article 2: All provisions contrary to the provisions of Article 1 of this Order are hereby repealed.

Done at Paris, 3 November 1936.

France maintained the requirement for selective yellow car lamps for almost 60 years. As late as 1988, French lawmakers were responding to citizen queries by saying the selective yellow lights were safer because of less glare and less light scatter with equal driver seeing ability. In the drive to remove trade and travel barriers by commonising vehicle technical regulations throughout Europe, the requirement was squashed in 1993 (along with unique vehicle lighting requirements in certain other countries) and white headlamps were allowed in France for the first time since 1937.