Where's my future-car?
November 25, 2006 1:54 PM   Subscribe

It seems that taillights have evolved rather radically from their humble origins, now featuring LED configurations spanning cars' entire back ends. Why hasn't this kind of innovation been seen with headlights?

I thought of a few questions along these lines last night while sitting in the back of a friend's van, watching the headlights around us on the highway.


1. Why don't car manufacturers use fluorescent or LED bulbs (backed by reflective material, just as incandescent bulbs are) in headlights? It seems to me that they'd be just as sturdy as incandescent bulbs, and probably provide brighter light with less energy required.

2. Are there practical reasons why car manufacturers continue to stick to the tried-and-true "two headlights, one on the left, one on the right" configuration, rather than using, say, a centrally mounted light bar? (Think something like the Millennium Falcon's propulsion bar, only on the front of the car and used solely for lighting purposes...) Or is it just convention?

When I discussed this with my friends, we speculated that it could be an issue of redundancy—i.e. if one gets knocked out, you still have one left. But then, I countered, couldn't that be addressed by mounting, say, two or more fluorescent tubes in the "light bar"? Or if fluorescent tubes are too fragile, perhaps multiple tiny white LEDs?

We also speculated that perhaps it was just a design/functionality issue, wherein, say, the grill is a standard air intake area for the engine, and it's easier to keep it there, rather than trying to create a radically new air intake system.

Any ideas which, if any, of these issues have curtailed the introduction of new forms of headlights?
posted by limeonaire to Technology (15 answers total)
LEDs don't heat up, which means that they don't melt snow off headlights like other headlights do. This is a real consideration, interestingly.

The 1948 Tucker had a center headlight. It looked stupid and didn't do much that 2 headlights couldn't already do. And that was a very, very long time ago.

And the 1st and 2nd generation Mercury Sable had lights all the way across the front. It looked stupid -- especially when some of the bulbs burned out.

Also, 2 headlights gives oncoming traffic a better perspective of how far away the oncoming car is, its angle, etc. If it weren't for that, it would make sense to just have a single headlight in the middle of the car, instead of two.
posted by JekPorkins at 2:02 PM on November 25, 2006

Easy. LED and fluorescent lights are not bright enough. Fluorescent bulbs are also pretty fragile.

There have been some innovations in headlights, mainly projector housings and HID lamps as well as adaptive (move when you turn) lights.
posted by mphuie at 2:03 PM on November 25, 2006

The 1990s Mercury Villager and Mercury Sable had light bars that stretched between the headlights. There's probably limited flexibility to do this, because of laws regulating the number and placement of exterior lights.

Wikipedia has a section on LED headlamps. It says that current LEDs have problems when used as headlamps, including low-temperature operation and heat dissipation. Here's an article that says LED headlamps are now being used in concept cars, and will be on the road soon.
posted by mbrubeck at 2:07 PM on November 25, 2006

Top Gear on the new Audi R8: One last option (due to be made available within six months of the R8's launch next May) takes the form of a set of ultra-high intensity projector headlamps, the first in a production car to feature LEDs alone.

How much more efficient are LEDs anyway? 40% better or so I guess? This wildly imprecise estimation seems to imply that the improved efficiency should be more than enough to make them worth the cost and complexity, over the life of a car.
posted by sfenders at 2:42 PM on November 25, 2006

Because there's no need to innovate? What's the problem with the current setup? You put a light on each corner to give you the widest possible spread, and give the car a face, and once you've done that, there's not many different things you can do.

With the back end, there's much more variability in design (of the car, not just the lights) and there's a whole bunch of lights that need to go there, and no natural configuration for them.
posted by cillit bang at 2:44 PM on November 25, 2006

I expect that some of the difference is due to headlights being for the purpose of seeing, while tail-lamps are for the purpose of being seen. This effects the angle of viewing needed, the kind of covering, etc., as well as intensity -- much easier to see a dim light in the dark than to see with a dim light in the dark.

I have a light-box that is an array of about 100 small LEDs and it is plenty bright. My guess is you could make an LED headlight, but it would be very expensive.
posted by Rumple at 2:52 PM on November 25, 2006

Also consider that you spend a great deal of time staring at the back of other people's cars, and less time staring at the front. Moreover, when you're behind a car, it's lit up by your headlamps, and when you're facing a car at night, you can't see much because the headlamps are staring you in the face.

So, put on your marketing cap and realize ... the back of a car is a branding opportunity. Nifty lights, a logo, etc. Simple little snazzy tricks to make a car look more high tech and safer than it really is.
posted by frogan at 3:10 PM on November 25, 2006

Headlights remain one of the most highly regulated systems on any vehicle.. And unfortunately for North Americans, the existing European standard, legal but not mandatory in the US, is still years ahead of current minimum DOT regulations. Perhaps some of the high-tech European models will pressure domestic automakers to let us "see" into the 21st Century
posted by BillsR100 at 6:23 PM on November 25, 2006

Serious nighttime trail bicyclists use high-intensity halogen lamps, despite the massive battery banks that only provide 90 minutes of light. It sounds out of place considering what they'll do to shave half a pound off the bike, so if LEDs were better, presumably cyclists would be using them.

Turns out it's trivial to set up an LED array that's more intense with less battery consumption, but nobody's yet engineered a well-focused LED headlamp. So LED lamps tend to diffuse at short range, sometimes at the expense of blinding your fellow riders. That's no good.

This isn't a direct answer for your question, but it's somewhat relevant. Automobiles do not currently have the same concerns cyclists do; a petro-fueled car has more power than it needs when running at speed, so a full array of inefficient headlights is not a problem. If LEDs aren't good enough for people who have to carry their own power, they probably won't be good enough where power consumption isn't an issue. On the other hand, LEDs are advantageous as taillights specifically because of their intensity; a couple LEDs plus a decorative reflector pattern makes for an elaborate light show that looks unlike anything in older cars. Bicyclists, too, use LED lamps front and back on their bikes to be seen; they're cheap and light and dazzlingly bright.

There may be engineering problems relevant to useful LED lamps as well; LED lifespan decreases dramatically when conditions aren't ideal (see 'thermal management' on EnLux' website for a short explanation), and they dim as they age, making their actual lifespan and efficiency significantly less than commonly assumed (an overview of problems and advantages on CENS.com).

The expectation is LEDs will take over in the cycling market eventually, but the technology's not ready yet. I think it's reasonable to assume this is true in the automotive world as well.
posted by ardgedee at 6:28 PM on November 25, 2006

Cutting edge bicycle light tech has gone way beyond halogen. High intensity discharge (HID) bulbs with overdriven ballasts are the state of the art, giving something the equivalent of 65 watts of halogen with a power draw of 10-16 watts. 3+ hours of light out of a system that weighs about a pound, battery included.

LEDs have come a long way from the days when they were only good for being seen, rather than seeing, but they are still pathetic when compared to the retina-frying punch you get from HID or even halogen. FWIW, many people use a combination of LED lights on the handlebars (for a broad diffuse glow), and a halogen or HID lamp on the helmet (for a long-range spot).

But getting back to the car... 2 headlights - one on each side - gives you an inkling of the oncoming car's width, and means you don't confuse it with a motorbike. Also, it allows enough light spill from the edges of the beam to illuminate the edge of the road, which is kinda useful for seeing if anything is about to leap out at you.
posted by tim_in_oz at 7:48 PM on November 25, 2006

ardgedee: For what it's worth, I think the LED technology available today, at the prices of today, is already able to remove incandescent from cycling. What is missing is products that use it - I think we're in that 2-year in-between period, where new products need to be designed to use the new tech, tested, manufactured, marketed, and gain market popularity, etc. But if you are a hobbyist, who knows where to get the right (currently pretty esoteric) supplies, you can build a lamp significantly better than any that has reached the market so far.

As to car headlights, I think the current solution does seem to be pretty optimal - it is hard to come up with a superior one, and car aethetics is conservative enough that breaking out of the headlamp-on-each-side box is not going to happen for reasons of style. Plus all the red tape. Adaptive headlamps seems more like the kind of innovation to expect.
posted by -harlequin- at 7:57 PM on November 25, 2006

Tail lights are designed to be seen by other drivers

Head lights are designed to help the driver see others.

Big difference.
posted by dendrite at 9:08 PM on November 25, 2006

The '66 Studebaker Sceptre (image) would have used
a single full-width tube designed by Sylvania, which designer Brooks Stevens found gave better highway illumination than sealed beams, without the glare.
Too bad that was just a concept.
    - quote from Prototype Cars (1981)

posted by Rash at 9:39 PM on November 25, 2006

Another quote, from this --
A historic development for the LED and automotive industries was the announcement in early 2004 of the first use of LEDs in the front end of a car. The 2004 Audi A8 6.0L used six 1-W white Luxeon LEDs in its daytime-running-lamp assembly.
posted by Rash at 10:19 AM on November 26, 2006

The short answer is the SAE has mandated the current paired headlamp system (either 2 or 4) and many areas have solidifed the standard into law. It would take decades to make an alternative 50 state/10 province legal. In BC for example you are permited only 6 headlamps (or fog/drivng lights) total and they must be mounted in pairs. If you wish to mount amber fogs you may mount two and only two.

cillit bang writes "Because there's no need to innovate? What's the problem with the current setup? You put a light on each corner to give you the widest possible spread, and give the car a face, and once you've done that, there's not many different things you can do."

Anyone who has every driven a car with good lighting could lecture at length on the defieciencies of the current headlight systems on even european spec cars. They lack range, cornering and differentiation (which is vertical seperation to make pothole stand out from shadows cast from rises)

Take a look at what competative vehicles driven at night mount (say WRC or Baja). In many cases the limit is the ability of their alternators to power the lights. However auto engineers also have to design systems that don't blind on coming traffic, somethng that say six Hella Rallye 4000s that monied rally competators might mount will do six ways from Sunday.
posted by Mitheral at 9:56 PM on November 28, 2006

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