[Aditya]

Evolution of Headlamps

Among the most important features of cars and motorbikes are headlamps. These are vital for driving in dark conditions. They light up the road ahead and help you see where you are going. In heavy rain, they help make your car more visible and easier to spot.

Headlamps have been seen on cars in the late 1800s. Since then, they have changed constantly, becoming longer lasting, more powerful and "intelligent". Let's take a look at how headlights have evolved over the years.

Acetylene Headlamps

The first headlamps used either oil or acetylene. These lamps were carried over from horse carriages. They had to be lit by a match and required frequent refilling. Acetylene was the referred choice because of its better resistance to rain and wind. They had a mirror behind the flame which helped project the light forwards.


Image source

However, the beam was not really focused. Instead, it was scattered and not spread evenly. Hence, these lamps were not very effective while driving. They did not last long and were soon replaced by electric headlamps.

Electric Headlamps

Electric headlamps replaced Acetylene headlamps in ~1900. These eliminated some of the problems that acetylene headlamps faced. However, the technology took some time to make its way to most cars. This was due to the need to create a dynamo that was small enough to fit into the engine bay, yet strong enough to develop power for the bulbs. This resulted in a very low light output. Still, these were the lights that set the direction for the development of headlamps.



Sealed beam Headlamps

Sealed beam headlamps were first seen in cars in the late 1930s. They used a parabolic reflectors, a tungsten filament, and a lens sealed together. Not only did these headlamps produce brighter and more focused light than earlier headlamps, they changed the style and looks of cars. too. An advantage of these glass headlamps was that they would not have the problem of oxidation. However, in the event of an accident, they could shatter and cause injuries to other road users. The bulbs put out little light considering the amount of power they used. Besides, the hot filament could leave dark residues on the glass.


Image source

In the early 1960s, halogen lamps made their way to cars. These were brighter and more durable. Visibility improved drastically.



Plastic headlamps

In the 1990s plastic headlights made an appearance. These allowed vehicle manufacturers to mould headlights into any shape they wanted. In the process, car designers got the freedom to style their vehicles to their liking. Being cheaper than glass, plastic headlamps were instrumental in building the road to the development of more complex headlamp setups in the years to come.



However, plastic headlamps had their disadvantages too. They suffered from oxidation and yellowing. Besides, as we all know, plastic is not exactly environmentally friendly.

High-intensity discharge (HID) Headlamps

High-intensity discharge bulbs made their appearance in the early 2000s. HIDs produce an electrical arc between two metal electrodes through an inert gas, inside a glass bulb to create light. They developed a lot more light compared to the power they use making them a lot more efficient compared to traditional bulbs. Even smaller HID bulbs could produce the desired amount of light which in turn means that there were few limitations to the alteration of the shape of the headlamps. Additionally, HIDs were available in various colour temperatures, which helped in increasing their appeal.



HIDs were also very popular in the aftermarket. However, traditional headlamp assemblies were unsuitable for fitting HIDs as they would scatter the light produced. Specific assemblies were required for the light to be focused where the driver wanted it to fall.

Light-emitting diodes (LED) Headlamps

Light-emitting diodes (LEDs) first appeared in the 2000s. Today, most of the cars available in the market (excluding the entry-level segment) are available with at least an option of LEDs. These headlights are very bright, long-lasting and require a lesser amount of power compared to halogen lamps.



LEDs were first used as daytime running lights (DRLs). Later, they were used for the low beam only and with time, even the high beam. The development of LED headlamps is truly fascinating. The adaptive high beam ensures that drivers of oncoming are not blinded. Adaptive headlamps also focus their beams appropriately on curvy roads using satellite navigation.



Laser Headlamps

Laser is the latest technology when it comes to headlamps. These laser beams offer an impressive vision and are very efficient. Three diodes pass blue laser beams into a prism which focuses them into one beam. This beam is passed through a phosphorous lens that transforms the light from blue to white, before hitting a reflector that redirects the beam onto the road. Laser headlights are substantially more efficient compared to LEDs.



However, laser beams can be limited when it comes to focus. Hence, they are used for high beams only. Laser technology is relatively new in headlamps and hence, available in cars from luxury brands only.

[Aditya]

Thread moved out from the Assembly Line.

[CentreOfGravity]

Thanks for ‘shedding light’ on this topic! I think this thread is inspired by this video that I had watched last month:

https://youtu.be/lVtnH0KscS4?si=Bzg-gxV2xpcLbR-b

I simply love LED headlights as long as they are stock and do not pose any inconvenience to other road users. But in old cars, I prefer halogen lights and hate getting them replaced with LED units, for they ruin the look and blind incoming traffic. As for the newer lighting tech like laser and matrix lights, I won’t comment on them until I can afford a car with these lights .

[saket77]

Good initiative to talk about various lighting options. Thanks for this crisp and precise thread.

The old acetylene lights in cars with mirrors acting as reflectors were interesting.
Coming to newer tech, I haven’t ever experienced the laser headlamp but having experienced the halogens and LED headlamps- I would pick the halogens anyday. Yes, they are inefficient in terms of power consumption and emit substantial heat, wasting precious energy but the resultant lighting belongs to a spectrum which is easy on eyes even after hours of long drive. Also, the comparatively warm light temperature works much better in rains, fogs and in presence of ambient lighting.

The white modern LED headlamps consume very less power (10-12watts) compared to the halogens (60w) and are good enough in pitch dark. However, the light scatters in adverse weather and with external ambient lighting. Also I found the these to be much lesser in terms of ‘throw’ compared to the halogens. Honestly, I feel that these white LEDs are more of a fad working only to project a more premium image of cars.

Would love to know the view points of other members.

[SuperGirl_Dad]

Originally Posted by Aditya

Plastic headlamps
Attachment 2635832

High-intensity discharge (HID) Headlamps
Attachment 2635835

Thank you for the excellent writeup! In which category do the Projector headlights fall? Or do they have a separate category?

[s2K_scorpioN]

Originally Posted by Aditya

Evolution of Headlamps

I know this post is centered more around the technology aspect of automotive lights, but I wanted to highlight the evolution of the design as well.

1900s: car headlights were simple round lamps, sticking out like lanterns from which they took inspiration from, most likely.

1920s - 1930s: they began to blend more with the car's body, becoming more streamlined and stylised.

1940s and 1950s: headlights became integrated into the fenders, and dual headlights became a thing, sophistication was introduced. The 1960s saw the introduction of alternative shaped headlights, deviating away from the traditional circular shape. This is also when the popular pop-up headlights were first introduced!!

1970s and 1980s: flush-mounted headlights became common to improve aerodynamics, with the square and rectangular designs becoming more mainstream. The 1990s brought in flurry of headlight designs, before pedestrian safety become a thing.

2000s - 2010s: headlights started to seamlessly integrate into the vehicle's body with sharp lines and angles. Later on, LED technology allowed for thinner, sleeker headlights.

Personally I feel design has become more minimalistic not just in the sphere of automotive headlights, but designs of car as a whole. Not just that, but also architecture and all designs. I think expression in the form of design is becoming more and more muted. Future seems a bit grim.

[Adam]

Nice writeup man, meanwhile let me talk some geeky stuff on lamps ��
Headlamp lens are mostly now made up of Poly carbonates as it is more susceptible to rock chips PC’s impact strength helps in avoiding cracks but plastic being plastic doesn’t have a good reputation on scratch resistance, inorder to improve the resistance headlamp lens are covered in a lacquer which in lamp terms called as an hard coat. This is what protects the lamps from getting scratched up.

Tail lamps on other hand uses Acrylic material such as PMMA for outer lens which aren’t good in impact resistance but bit cheaper and flexible in some manufacturing operations. But it doesn’t have any lacquer so please be gentle with the chemicals while cleaning your tail lights.

When coming to the techs there are quite a lot depending on the features needed and the price categories. Nowadays most manufacturers use LED with Reflector based setup, as it’s kind of cheap to manufacture when compared to projector or D lens setup.
D lens lamps from outside looks exactly like a projector but the tech used is totally different and are mostly used in two wheelers due to the limited beam width and intensity and its difficulty in integrating both high and low beam in a single unit. But as some of you might have seen some ice cube designed lights on some cars which also use similar kind of technology.

For rear lighting now there are more technologies depending on the design, Audi even started using OLED panels on tail lamps to get different signature lightings.

Lighting is such a vast topic in Automotive and also is one of the most regulated one. So when you see a vehicle with damn intense or pathetic light output from factory remember it’s all been certified by our regulatory authorities under different classes.

Originally Posted by SuperGirl_Dad

Thank you for the excellent writeup! In which category do the Projector headlights fall? Or do they have a separate category?

Projectors just use a different method to illuminate, the outer enclosure of the headlamps will be plastic but the projector lens can be made up of plastic or glass, due to the complexity in manufacturing of glass mostly all manufacturers now use plastic projector lens. Also the light source are now mostly LED’s which emit less heat and can disperse heat through the PCB’s and heatsink there isn't a necessity to use glass.

Some older model projectors have a reflector inside and halogen or HID for illuminations, the light get reflected on the inner reflector and get focused out of the projector lens, in between there may be a mechanical or fixed shutter to regulate low and high beams.

New gen projector mostly don't use any mechanical shutter and is having different construction using multiple LED’s and collimators for diverging light beams.

[Jeroen]

Thanks for sharing! Lovely write up.

Just to add a little anorak fact;

For decades (since 1939) French cars had yellow headlights! The idea was that with the relatively weak bulbs of the days, yellow light would reflect less water and hence would provide a better view and thus safety when driving in rain and foggy conditions.

So cars had yellow bulbs or yellow headlight covers installed. In those days when visiting France from abroad you were obliged to put special yellow headlight covers on. Nobody did, just like nobody puts those special stickers on their headlights when visiting the UK.

Even so, it means that many French Classic Cars still have yellow headlights. This "yellow-period" came to an end in 1993 as part of EU harmonisation on car headlights.

[100Kmphormore]

Interesting topic of discussion, and how many myths regarding this very simple topic exist. Except RE headlights (exception 450 and 650 cc bikes) which continue to exist in the 1900 era, mostly have this LED fad. The only proper implementation of LED based light - adaptive laser headlights in BMWs were my favourite, especially on my night rides, where a simple flick to indicate they were overtaking from 200 m away, powerful yet never blinded us looked amazing. Apparently they got discontinued in the recent models.

[SuperGirl_Dad]

Is there any standard on where the headlight should be placed with respect to car height? Minimum and maximum lumens allowed?

In the Indian context trivia,

Most types of headlights across generations - Honda City?
Largest - Nissan Sunny?
Longest - Innova?
Smallest - 2023 Verna?

[lemedico]

Originally Posted by SuperGirl_Dad

Is there any standard on where the headlight should be placed with respect to car height? Minimum and maximum lumens allowed?

In the Indian context trivia,

Most types of headlights across generations - Honda City?
Largest - Nissan Sunny?
Longest - Innova?
Smallest - 2023 Verna?

Also, most headlights: Mahindra Thar.
The amount of extras plonked on a regular Thar is just incredible. (NO) thanks karol bagh

[Adam]

Originally Posted by SuperGirl_Dad

Is there any standard on where the headlight should be placed with respect to car height? Minimum and maximum lumens allowed?

In the Indian context trivia,

Most types of headlights across generations - Honda City?
Largest - Nissan Sunny?
Longest - Innova?
Smallest - 2023 Verna?

Indian Automotive regulatory standards are mostly a derivative of European standards. And there are few classifications of headlamps illumination such as Class A, B, C and D, some countries have mandated every new vehicle to follow particular class depending on several factors.
When a manufacturer make a vehicle for a particular market we can declare which is the class of lamp we are going ahead with, which mostly will be as per the minimum regulatory requirement of their intended market, once they choose it they will develop lamps which will meet the distance, illumination and intensity requirements as per that class. This lamps will go through multiple simulations and optical photometry tests by the lamp manufacturers and eventually by a certifying agency.

So to answer your question , installation height is not directly regulated, but once its installation height is fixed the cut off of the high beam and low beam and its intensity is regulated. Also the distance between each lamps , indicators etc are tightly regulated in each vehicle models.
You can refer to the below link to understand some geeky stuffs on Lamps regulations 🤓.

https://www.araiindia.com/cpanel/Fil...008_Rev1_F.pdf

Lighting in automotive is a vast subject and have some grey areas too, especially in India where at times some new innovations aren’t welcomed unless and until someone take the risk and prove it to regulatory agencies.

[1.2GT3GT]

Originally Posted by Jeroen

The idea was that with the relatively weak bulbs of the days, yellow light would reflect less water and hence would provide a better view and thus safety when driving in rain and foggy conditions.

Maybe a bit off-topic, this is probably why factory fit dedicated fog lamps continued to use yellow light (until recently) even when the headlights switched over to a much whiter colour temperature (more so with LEDs).

[yasirsait]

Originally Posted by SuperGirl_Dad

Thank you for the excellent writeup! In which category do the Projector headlights fall? Or do they have a separate category?

There are two components to headlights - light source and housing.
The article here details the different types sources of light in headlights.
The housing itself has traditionally always been reflector housing until around the 2000s when HID light source stated being used.
From then on, in order to focus the beam, a lens was used in front of the light creating the projector housing.
Almost all LED lights today and many halogen lights use projector housing.
Few halogen lights today use reflector housings.

[anjan_c2007]

My grand uncle owned a Wolseley with acetylene lamps as his first car. He changed cars often. About his Wolseley, I have only faint memories of what all he had said as I was born much later to be able to see that Wolseley.

Many of the older cars had no batteries but had the magnetos generating power through the 6V AC electricals. The cranking handle would be welded to the crankshaft extension outside the engine block and hence self starter would not be a part of its OE. The good ol' carefree days.

Coming to headlights, the switchover from the glass to plastics aided designers though, but these plastics would turn dull towards faint light yellow shades, and unless some good TLC was done, the intensity of emitted light would be impaired.

The evolution to HID then LED and now Laser headlamps are progressive, unless these cause blinding effects on ghe oncoming traffic and also pedestrians.