I am frequently asked why night driving has become such a strenuous problem, by people that know I have been involved in automotive road lighting technology for the past 55 years. The technological history of automotive headlamps in the USA leads to the cause of the problems of the last 25 years.

1892-1906, the only lights were oil lanterns that only indicated the approach of the vehicle.

1906-1912, the road illumination was the reflected light from a small acetylene burner. The projected beam was similar to a flashlight.

1912-1915, this was the first use of an incandescent lamp and a reflector. The lamp was a vacuum lamp and the bulb blackened rapidly. The projected beam was also similar to a flashlight.

1915-1924, a gas filled incandescent lamp replaced the vacuum lamp and diminished the bulb blackening problem. A spread lens was added to the reflector. This was the first controlled beam headlamp. This was a single beam called a driving beam.

1924-1934, the single filament bulb was replaced by a two filament bulb. The added filament was called the dipping filament and provided road light lower and to the right. The dipping beam would become the present "low" beam. A major problem was interchangeability of bulbs as the position of the filaments was critical.

1934-1939, the mounting of the two filament bulb was changed from a bayonet socket to a prefocused ring soldered to the bayonet base that was precision located with respect to the filaments. The prefocus ring mated with three pins attached to the reflector. The results were the best yet, but there was still the problem of bulb blackening and also oxidation of the reflector surface. The spread lens was hinged to the reflector and could be opened to change bulbs and polish the reflector.

1939-1957, the Sealed Beam lamp replaced the small gas filled two filament bulb and the reflector housing. The Sealed Beam lamp was a PAR56 (7 inch diameter) reflector and lens permanently sealed together to form the bulb. The reflector was aluminized for a more reflective surface. The filaments were mechanically located with respect to the reflector. The large complete bulb was pumped and filled with an inert gas. The reflector tarnishing was eliminated and the bulb blackening was minimized due to the large inner surface of the bulb. When a Sealed Beam bulb was replaced, it was a complete new system.

The Sealed Beam had a new very important feature, there were three projections on the outer surface of the spread lens that permitted precision aiming of the headlamps. The high beam driving lights should be horizontal and the low beam passing lights should be "dipped" one half of one degree below the horizontal. No light above the horizontal is required or desired as light above the horizontal is seen as "glare" by approaching drivers.

The PAR56 Sealed Beam was constantly improved during the next 18 years and would become the best high production road lighting system in 100+ years of automobile and truck travel.

It is important to point out that from 1892 to 1957, headlamps were 100% developed for the benefit of the vehicle driver.

In 1958, the 7 inch diameter PAR56 was replaced by two PAR46 (5 ¾ inch diameter) Sealed Beam bulbs. This was the beginning of the present trend to make the headlamps look "cute" in the daytime at the expense of the vehicle night drivers vision. Initially the change was relatively minor because the filament wattage was increased to make up for the smaller less efficient reflectors. In 1975, the PAR46 reflectors were modified to a rectangular shape, and again the filament wattage was increased to make up for the loss of reflector surface.

At this point, it is clear that it is the automobile manufacturing companies that are responsible for the modifications of the Flagship PAR56.

In 1978, the Department of Transportation (D.O.T.) ruled in favor of Halogen Sealed Beams. This regulation was of no value to the vehicle mfg. companies or the night drivers. However, the regulation set the stage for the present problems of high glare and poor road illumination.

The halogen Sealed Beam consisted of a small single end bulb (~5/8 inch Diameter) with one or two filaments. The halogen lamp is mounted in the Sealed Beam bulb in place of the filaments. There is no way to precisely locate the filaments and the halogen lamp is lighted and moved around until a position is found that where at least the minimum required beam candlepower is reached and the uncontrolled glare does not exceed the maximum allowable candlepower. The Halogen Sealed beam is no longer a precision optical lighting instrument.

The worst problem is, it is not possible to accurately aim the halogen headlight on the vehicle except to go back 30 years and see how they look on the garage door. The net effect is going from minimal glare and maximum road illumination to maximum glare and no concern about road illumination greater than the minimum required by law.

In 1989, the Aerodynamic Headlights, an attempt to make the headlamps look like something from Star Wars were installed on new automobiles. The halogen capsule is replaceable, the reflector is designed to control the light distribution and is enclosed in a clear plastic housing. The first model was the 9004 unit and the road illumination was the worst since the mid 1920s. The low beam filament wattage was at least 10 watts too low. Thousands of drivers had to add fog lights for additional illumination. In 1992, the 9004 system was replaced by the 9007 system with higher wattage. However, the bulbs are not interchangeable.

At the same time, General Motors developed an improved system using a 65 watt #9005 halogen bulb for high beam and a 55 watt #9006 halogen bulb for low beam. This system with separate reflectors for each bulb allows superior road illumination compared to the two filament single reflector 9004/9007 system. However, there are still the problems of aiming, replacement lamp consistency, outer plastic housing degrading due to UV as well as surface roughening due to sand blasting.

HID Headlights

Some "top of the line" automobiles have HID (High Intensity Discharge) headlamps where the filament has been replaced by an electric arc. The HID headlights do provide improved road illumination for the driver. However, the HID lamps also emit bright blue glare and are despised by 99% of the approaching drivers, especially older drivers and drives people with cataracts off the road. The situation would be improved if the HID lamps were aimed properly.

The HID headlamps spawned some unexpected problems. The bright blue HID headlights has become a prestige item and people are buying high color temperature halogen headlamp bulbs that simulate the blue HID bulbs. The bulbs serve no useful night driving purpose and are an additional source of high brightness glare. In addition, the spherical candlepower is reduced by the tinted glass or filtering, resulting in less useful road lighting.

Problems and Solutions

The minimum and maximum legal headlamp photometry is measured at 25 feet with photocells at specified positions with reference to HV, where H is a horizontal plane through the center of the headlamps. The headlamps have to be correctly aimed for the photometry evaluation. The D.O.T. and NHTSA have rules but there is no enforcement and no State inspections as there once was. A driver only attracts attention when a bulb is out.

There is nothing that can be done to improve the two filament, one reflector 9004/9007 systems that are already on the road.

However, there is a solution for the single filament, single reflector 9005/9006 systems manufactured from 1990 through 2005. The solution is a new high technology replacement bulb that increases the high beam light on the road by about 50% and the low beam light on the road by about 87%. The bulbs are HIR bulbs where the bulb is somewhat spherical shaped in the area of the filament and coated with a transparent infrared reflecting coating that reflects radiated infrared back at the filament and heats the tungsten filament in addition to the electric current. The result is the filament is over heated and the correction is to make the filament larger and a larger heated source increases the spherical candlepower and the beam candlepower on the road. The new bulb is referred to as HIR-1/9011 (high beam) and HIR-2/9012 (low beam). The bulb rating characteristics of the HIR bulbs are exactly the same as the HB3/9005 and HB4/9006 except for the higher light output.

I have supplied all of my extended family and friends with HIR bulbs. The common comment is "it is like driving on high beams but nobody blinks their lights at you".

Most people are not aware of HIR-1/9011 and HIR-2/9012 bulbs that have been customized for 9005 and 9006 applications because they are not sold by automotive parts stores. However, the bulbs are available.

David R. Dayton

Stuart, Florida

Email drizday@bellsouth.net