Headlight Concerns and Future Concepts

Growing up in central New York near Ithaca in the 1960’s, I was part of a large middle class family consisting of six kids and my mom and dad.  We lived what I think is a simpler life, without cable TV or a 24-hour grocery store.  We traveled to Ithaca to shop for clothing and related items, and we seldom went out to eat with the exception of an occasional pizza from the local pizza shop.

Times have really changed.  We now have the option to shop at stores whenever we have a few spare minutes, and the open-24/7 stores offer many more services than those did during my simple times growing up.  The bottom line: we are making more trips at all hours of the day than we did over four decades ago.  We are traveling without regard to the dangers of driving at night.  We need better quality headlights for our vehicles than we have had in the past.

As our need to drive more at night has increased, the idea of what constitutes a quality forward lighting systems has changed as well. Our need for uniformly spread headlamp beam with enough seeing distance to see down the road has become increasingly important.  The University of Michigan Transportation Research Institute (UMTRI) has studied the low beam pattern of many headlamps on the road today and discovered something very interesting: many of today’s low beam headlamps only have enough “reach” to provide emergency stops (with some safety margin) if you are driving less than 45 miles per hour.  Driving any faster than 45 mph may allow you to detect targets in the road but they do not have sufficient stopping distance to stop the vehicle before hitting them.

As the largest population segment (the baby boomers) gets older and nears retirement age, we have seen an increasing number of complaints about glare.   As a matter of fact, in 2001 the National Highway Traffic Safety Administration issued a request for comment on the glare experience of the public, and they received more comments on this issue than any other topic.   Glare is present in two varying levels: discomfort glare and disability glare, and the volume of complaints is increasing.  Discomfort glare is simply the expression of glare that is painful to look at, while disability glare represents the point to which you are unable to safely drive, due to the brightness of oncoming lights. Today, we have a situation that requires more light down the road (largely in low beam functions), but we need to come up with a better way to reduce the amount of glare as well.

 

Light Sources – New light sources have emerged that are contributing to the issues of glare and poor low beam performance.  Incandescent and halogen light sources have been available for many years, but the emergence of HID or Xenon Headlamp bulbs has ushered in new areas of concern.  HID equipped headlamps can often be identified by the significant improvement light output, but they may give a “cool blue” color temperature in most situations.  The beam from an HID headlamp has a great deal of uniform light and its reach down the road is great.  Many people who have HID equipped vehicles report that they enjoy the driving experience behind HID equipped headlight systems.

It has become an interesting aftermarket trend to sell “HID blue tinted” halogen bulbs or HID replacement kits, which we strongly recommend that you understand the potential risks before purchasing.  If you see an extremely blue headlamp on an older car, with blue headlamps, this is likely the use of an illegal HID kit or a blue-tinted bulbs.  This aftermarket product has become quite popular, but causes a tremendous amount of glare. The bulbs are often sold with a label “For off road use only”.  A bit of advice:  Only use bulbs that are labeled “DOT” and make sure that they are the same bulb type as was recommended by the manufacturer.  “DOT” labeled bulbs are available that are both tinted and have additional features designed to improve the performance, and make acceptable choice for most applications.  Bulbs with the “For off road use only” designation may even damage your existing headlamp lens and housings.

LED Headlamps are also beginning to emerge.  Many of these headlamps have used computer based optics design technology, which is helping to extend the performance of the headlamp, reducing the amount of uncontrolled glare light and increasing the ability to see down the road.  LED technology in headlamps has all the great features we have grown to enjoy in exterior lighting like: lower current draw, less heat, longer life, faster start up time, better performance in cold weather and richer colors.  We like what we see with the LED headlamps and we believe that the customer experience will even be better forward lighting when the technology matures.

Concept – When headlights were first developed, it was thought that high beams would be the default driving lights, and you’d only temporarily switch to the low beams when approaching someone in traffic or trailing behind another vehicle.  That’s not how drivers ended up using them.  Most only rarely use their high beams, to avoid blinding oncoming drivers, and it’s become a legal requirement to have them off when another car is approaching.  People actually underuse their high beams, which is a strange thing to say, and likely don’t recognize how limited their vision is with low-beam lights. In another recent study by UMTRI where they looked at driving habits and relating to the use of lighting- In the city 93% of the time people are using low beam, 5% of the time High beam headlamps are being used and the other 2% are using no lamps when they need to.  Older drivers tend to use high beam headlamps more than younger drivers.   Younger drivers tend to drive without headlamps at night at a time when they should be.

Glare – Glare remains a major problem in North America today.  Five causes of glare that are apparent are HID light sources (or sources that are likely illegal that look like HID’s), cleanliness of the headlamps, haze from abrasion and chemical attack and improper aiming of the headlamps.   Efforts need to be taken to improve the performance of headlamps to reduce the glare.

Future – I am often asked, “what will we be seeing from headlamps  in the year 2020?”  To answer that question, I would like to share with you some future needs that I see for the application.

1)  First, we need a headlight beam that has uniform optical pattern with enough reach to allow for safe driving with low beam headlamps at 55 mph.  Advanced engineers are looking at a concept that is beginning to be demonstrated in Europe called Adaptive Main Beam (AMB) headlamps.  AMB headlamps will have only one beam much like our high beam pattern that we have now, but that will allow for a very comfortable driving experience at night.  You ask, what happens to glare control?  The simple answer is that the lamp will be equipped with “beam blockers” which will allow for mechanical or electronic methods to block the beam when shown in the direction of on-coming traffic.  This technology also has provisions to prevent blinding the back of a car or truck you are trailing behind.  The first demonstrations have shown a great deal of promise and I expect this to emerge as the next renaissance in forward lighting technology.

2)  Another need of headlamp technology is for increased light output with lower power draw.  The continued path of increasing lumens per watt and the decrease in lumens per dollar shows clearly that LED light sources will become the dominant technology for not only headlamps but for all of the exterior and interior lighting on cars and trucks.  LED sources can be integrated into the AMB concept.

I believe that we may see, in 2020, some of the first interactive cars and trucks which will talk to each other and improve the driving experience.  The first technical demonstration of this will take place this summer, in Michigan, USA.  Interactive cars and trucks with the improved adaptive main beam technology hold promise for a continued improvement in driving safety, making the trip to the store or the basketball game quite a bit safer in the future.

Brad Van Riper
Sr. Vice President of Research & Development , and Chief Technology Officer
Truck-Lite Co., LLC

Filaments, Arcs and Diodes

COMMON LIGHT SOURCES USED IN FORWARD LIGHTING SYSTEMS –

We can begin to discuss the ways to measure the many specifications, ratings and values of various lighting systems (and there are a considerable number), but it’s helpful to first discuss the various lighting technologies available.  Light sources can basically be categorized into three distinct classes: 1) incandescent light bulbs, which use heated, coiled filaments, 2) high intensity discharge systems, which use arcs of intense light, and 3) light emitting diodes, which use energized crystals and semiconductors to create light.  Understanding the way each technology works will help when we refer to the strengths and weaknesses of each, and we can explain better how each technology relates to the specifications, ratings and values.

LIGHT BULBS (filaments)
Incandescent light bulbs, technology nearing 133 years old, are still found in many of today’s lighting applications.  However, they are falling out of favor due to limited operating life, unreliability and poor efficiency.  Still not very different from the bulb Thomas Edison patented in the 19th century, today’s incandescent bulbs operate through a glowing tungsten filament filled with inert gas.  A coiled piece of tungsten alloy is energized and enclosed in the ever-familiar glass bulb housing, where the filament heats up to significant temperatures to generate the glow now synonymous with the light source.Incandescent Light Bulb

There are many points of concern with the filament-centered technology.  For starters, filaments and their heated, delicate state are very prone to “break” due to the slightest bumps, shaking or voltage spikes.  Tungsten actually gets more brittle as it operates.  Have you ever had a headlamp fail simply by driving over a pothole or starting your car on a cold winter morning?  It’s that common and it’s that easy.  Incandescent lamp failure is something everyone is familiar with.  Even the sound of a “burned out” light bulb is familiar to most people.  That sound you hear when shaking the bulb is nothing more than the pieces of a broken or collapsed filament.  As voltage gets higher, filaments get thinner and are even more prone to fracturing.  With the internal components alone being linked to failure, the delicate design of the thin, glass surface won’t hold up to much more.

Another challenge in the incandescent light bulb’s history is the color the source creates.  As the light it generates is little more than the glow of heated tungsten, the light output matches the yellow/orange hue as it’s passed out of the light.   Yellow light tones tend to “wash out” against browner shades in nature (dirt, dust and sand), and fade into the edges of roads too easily.

While aging lighting systems utilized a complete sealed-lens assembly (which was done mostly to promote lamp life), modern vehicles are more likely to use bulb-replaceable systems, which allow people the option of upgrading to brighter, longer lasting incandescent bulbs.

The efficiency of the incandescent light bulb in general has led to development of additional of more promising sealed-bulb technologies, including halogen systems, and more.  To their detriment, all of these sources fall below 2,000 hours of operation, create a light color on the yellow side of the spectrum, and offer light output that doesn’t meet the levels of newer technologies.

Better than the fire-lit torches and acetylene lights it obsoleted, the invention of the incandescent light bulb was historic.  However, its life has also seen the Ford’s Model T grow up into today’s Mustang.  Likewise, the lighting technology has grown up as well.

HIGH INTENSITY DISCHARGE (arcs)

In addition to halogen light bulbs, there is another glass, gas-filled lighting option available: High-Intensity Discharge (HID) technology.  HID systems use a gas-filled tube, with electrodes at each end, to create a “lightening-like” arc of light from one side to the other.  The glass tube contains a mixture of xenon gas and others (which is why HID bulbs are often referred to as Xenon bulbs).  The sealed tube is met with a charge at each end, regulated by an external controller called a ballast.  The ballast generates a significant amount of power, roughly 2,000 volts, and regulates and maintains the current to keep the arc constant.  If you listen closely, you make hear a small “crack” of the arc when HID lighting systems start up.High Intensity Discharge

HID lighting systems represent a significant source of light output, much more intense than that of incandescent light bulbs, but still less efficient than the lumen per watt rate of LED technology (as you’ll read below).  A noticeable factor in many HID headlights is the color tone.  Many systems generate a bluish tint of light, which can be harsh to the eyes of oncoming traffic.  The light intensity isn’t the cause for this as much as the unnatural light is to the human eye.  The blue hue, as harsh as it can be to others, doesn’t offer much help for the driver either.  The further away from “white” that a light gets, the less its output assists with visibility.

HID systems take the form of a bulb, like traditional incandescent systems (just adding the external ballast control module).  Typically rated at 3,000 hours of operation or less, concerns for their dependability and life span can make it difficult for many to explain the significant cost increase.  For instance, if your overall average speed is 30 mph, you will likely have to replace an HID bulb at 90,000 miles!  It could get expensive.

If HID technology is that of your choosing, don’t confuse it with blue-tinted halogen bulbs.  The inexpensive replacement lights do nothing more than cast a blue light color, which often decreases the available light output of the original bulb, and might even be illegal for use on the road. If you have driven behind HID bulbs, you know that they can be an effective solution, and tinted halogen lamps fall quite short of the same output.  With any replacement bulb, be sure that the bulb you choose is the exact replacement that the OEM recommends, and look for the “DOT” marking on both the packaging and the capsule.

LIGHT EMITTING DIODES (diodes)

Light emitting diodes, or LED’s, have become a much sought-after technology for a growing number of lighting applications.  In basic terms, LED’s are small crystals on semiconductor material, which generate light when met with an electrical current.  Very small in size, (just a few millimeters), the material can be installed in-line on electrical surfaces, creating fractionally small light sources that can be used in a variety of applications.

While LED’s are small in size, they are capable of creating significant light output with far less power than what is required by traditional incandescent and arc-based lighting technologies.  Whereas traditional bulb-driven technologies work through resistance of a coiled filament, the majority of the power is lost to heat.  LED’s don’t operate through resistance, and their light output can be described more as physical reaction.  Without using a filament or requiring an enclosed-gas atmosphere to operate, the small but efficient light sources last multiple times longer than other light technologies.Light Emitting Diode

LED chips themselves can be created to generate a variety of colors, and are capable of creating pure, white light.  By creating light that’s closer to the color temperature of daylight, road signs, road lines, road markers and objects at the sides of roads are more clearly visible.

LED’s represent much smaller, more concentrated sources of light than other lighting technologies. While the source of light offers more lumens per watt than any other light source available, the entire forward light output is dependent upon three very distinct factors: quality LED’s, efficient optics design and efficient thermal management (heat transfer).  It’s important to use high performance, pure white LED arrays, but it’s equally important to spread the light output cleanly, reaching the right distances and intensities for required for each lighting application.  [Inset diagram of triangle]  Thermal management, or the act of ushering heat away from the LED as it operates, is integral to providing long life of operation and maximum efficiency.  It’s with these principles that effective LED lights are usually contained in their own, unique housings, with their own, unique optics systems.

The LED technology roadmap for the future shows both continued increases in output per watt, improved consistency from diode to diode, and lower cost per lumen.  The future is bright for continued development of LED technology.

That’s a condensed explanation of the three basic categories of lighting used today.  There are certainly other, less-utilized technologies, and some of the above-mentioned technologies operate better through advancements made by lighting manufacturers, but it should give some general background to how they work.

Check back soon for our next Lighting Education topic, when we take a look at the lumen rating, and learn how (or if) it should impact your buying decision.

Jerry Lee
Marketing Communications & Services
Truck-Lite Co., LLC

How bright is that headlight?

“How bright is that headlight?” This seems like a simple enough question, doesn’t it? An anticipated and seemingly straight-forward answer would be “very bright”, but that’s not the answer most people are looking for. They might want a value, but visibility is a subjective process, and values aren’t subjective. It’s not a bad analogy to compare lighting to music. Would you rate a song good or bad based on its volume? I wouldn’t. Music’s enjoyment comes from a variety of nuances (and sometimes through cleverly dressed performers). In the same way, lighting is subjective, and can’t be explained with a mere number. You have to turn them on, take a look, and judge them in the environment in which you need them. The problem in providing a straight-forward answer, is that it’s simply not a straight-forward question.

Incandescent home light bulbs are in the period of obsolescence right now. They’re on their way out because everyone got smart to the fact that they’re wasteful and inefficient. [On a side note, what will happen to the analogy of a light bulb equating to a good idea, once everyone realizes how outdated the light bulb is? Let’s table that for now.] Light bulbs were rated based on how much energy they burned through. 10 watt light bulbs used 10 watts of electricity. 60 watts used 60. Increased power and resistance created a brighter burning filament, which generates more light output. It provided a much simpler answer to the question of “how bright is that bulb.” However, the convenience in that answer is dying with the technology. Today, you’re going to want to see to believe!

Part-for-part, LEDs operate at a fraction of the power draw of incandescent light bulbs, as do other more modern technologies. HID and xenon light sources operate by causing an arc within a gas-filled bulb tube. Fiber-optics use plastic threads to carry light from an electrically driven light source. Each one of them has a very different relationship between power consumption and light output. A simple number or rating may not translate directly from one technology to another. Is classical music louder than country? It’s just not an apples to apples comparison, and vehicle headlamps couldn’t be farther from household light bulbs if they had antlers. There are concerns over efficiency of operation, power draw, and the science of lighting that paint a full picture in detailing the best lighting choices.

The difficulty in judging a headlight’s performance comes with an understanding of what a headlamp “does.” They don’t just shine light straight out, covering the road without blinding other traffic, making the world safe. They refract, diffuse and enhance light, and perform a number of tricks to “land” light where it needs to be. To make things even better, all of the lighting technologies mentioned here don’t even create the same color of light. Some fade into the ground, while others offer more defined road signs. Some are easy on the eyes of oncoming traffic, while others will get you a “flash of the high beams.” Oddly enough, lamps that are harsher to oncoming traffic… in many cases… aren’t brighter at all. They’re just harsher to the human eye.

Throughout this blog, we’re going to take a look at forward lighting, from headlights to fog lights, to discuss the ways you can become a good judge of lighting. Many factors go into reviewing an effective headlight, including pattern coverage, color temperature, artifacts, glare, and yes, brightness. We might even discuss reasons why an intensely bright headlight would be the worst to drive behind. We’ll use analogies, comparisons, and possibly even charts and graphs, and we’ll ultimately try to get the point across that you can’t always judge light by a number.

Jerry Lee
Marketing Communications & Services
Truck-Lite Co., LLC