Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Powerful LED-based train headlight optimized for energy savings

13.02.2018

Careful LED placement cuts down on wasted energy

Researchers have designed a new LED-based train headlight that uses a tenth of the energy required for headlights using conventional light sources. If operated 8 hours every day, the electricity savings of the new design would reduce emissions of the greenhouse gas carbon dioxide by about 152 kilograms per year.


A new train headlight design uses two half-circular parabolic, or cup-shaped, aluminized reflectors with high-efficiency LEDs placed in the plane where the two reflectors come together. Combining the strong beams from each reflector generates the light intensity necessary to meet safety guidelines.

Credit: Wei-Lun Liang, National Taiwan University

Train headlights not only illuminate the tracks ahead, they also play an important role in rail transportation. Because trains are difficult to stop, the headlights must be visible from a distance far enough away to give people or vehicles on the tracks ample time to move out of the way. Traditional train headlights, which use incandescent or halogen bulbs, are bright enough to meet safety regulations but are not very energy efficient because most of the energy powering the light is converted into heat rather than visible light.

Researchers led by Guo-Dung J. Su from the Micro Optics Device Laboratory of the Graduate Institute of Photonics and Optoelectronics at National Taiwan University, Taiwan, were approached by the engineering and design company Lab H2 Inc., to design locomotive headlights that use LEDs as a light source. In addition to requiring less energy, LEDs also last longer and are smaller and more rugged than traditional light sources.

"Some LED headlight products sold on the market are designed with many LEDs that have outputs that overlap in large sections. These designs waste a lot of energy," said Wei-Lun Liang of the Micro Optics Device Laboratory, who was instrumental in designing the new train headlight. "Our research showed that electricity use can be reduced by focusing on the best way to distribute the LED energy equally."

In The Optical Society journal Applied Optics, Liang and Su report a new train headlight design based on ten precisely positioned high efficiency LEDs. The design uses a total of 20.18 Watts to accomplish the same light intensity as an incandescent or halogen lamp that uses several hundred watts. The new headlight can also be dimmed by turning off some of the LEDs to avoid blinding waiting passengers when the train passes a platform, for example.

Designing for energy efficiency

Much like those used for cars, train headlights typically combine a light source with a parabolic, or cup-shaped, reflective surface that focuses the emitted light into a beam. Although LEDs are a great option for saving energy, the most energy-efficient LEDs emit smaller spots of light. For this reason, the researchers had to combine the small outputs of multiple high-efficiency LEDs into a larger circular output to create a beam large enough to use as a train headlight.

"Combining several LEDs is more expensive and consumes more electricity than using a few single LEDs," said Liang. "Thus, we needed to determine how to best position the lowest possible number of high-efficiency LEDs needed to meet the requirements by analyzing how the parabolic surface reflected the LED lights."

The researchers' goal was a headlight that would provide light 1.25 times the brightness required by U.S. federal regulations. These regulations require train headlights to have a peak intensity of at least 200,000 candelas and illuminate a person at least 800 feet in front of the headlight.

Positioning the LEDs to save energy and meet federal guidelines came with several challenges. The researchers had to be careful to overlap the LED outputs just enough to create a large beam, but not so much that more LEDs, and thus more energy, would be needed. Also, the LEDs must be placed far enough from each other for heat to dissipate to prevent circuit damage.

Positioning the LEDS To create a high-efficiency train headlight, the researchers used two half-circular parabolic aluminized reflectors. When used together, the strong beams from each reflector combine to generate the light intensity necessary to meet federal guidelines. This design also simplified placement of the circuits needed to power the LEDs because they could be housed in the horizontal divider separating the reflectors.

To determine where to place the LEDs in the reflectors, the researchers first estimated the best location of each LED and then used a series of tests and simulations to fine-tune the final position for each LED based on its corresponding illumination pattern. "Other scientists can use the linear equation we derived for deciding the approximate positions of LEDs for other applications," said Liang. "This can substantially shorten the time required to determine LED positioning before fine-tuning the positions."

The researchers point out that headlights typically use a complete parabolic reflector surface. "We believe this is the first design to use a combination of two semi-parabolic reflector surfaces," said Liang. "By systematically analyzing the design to determine the best placement of the LEDs in the reflector, we were able to minimize electricity consumption while satisfying requirements associated with traffic safety."

The researchers are now working to turn their design into a commercial product. Even though the new design exhibits low power consumption, it still generates some waste heat. Before the design can be commercialized the researchers will need to develop and test a heat dissipation system for the new headlight.

###

Paper: W.-L. Liang, G.-D. J. Su, "Design of a high-efficiency train headlamp with low power consumption using dual half-parabolic aluminized reflectors," Applied Optics, Volume 57, Issue 6, 1305-1314 (2018). DOI: 10.1364/AO.57.001305

About Applied Optics

Applied Optics publishes in-depth peer-reviewed content about applications-centered research in optics. These articles cover research in optical technology, photonics, lasers, information processing, sensing and environmental optics.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.

Media Contacts:

Rebecca B. Andersen
The Optical Society randersen@osa.org
1-202-416-1443

Joshua Miller
The Optical Society
jmiller@osa.org
1-202-416-1435

http://www.osa.org 

Joshua Miller | EurekAlert!

Further reports about: LED LEDs energy savings light source low power consumption optics

More articles from Power and Electrical Engineering:

nachricht IHP technology ready for space flights
20.08.2018 | IHP - Leibniz-Institut für innovative Mikroelektronik

nachricht It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries
20.08.2018 | Forschungszentrum Jülich

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

20.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>