The speed at which LED lumen output is increasing is staggering. Bridgelux has just released an LED with 135 lumen/W. They were able to get commercial grade performance from a silicon substrate LED for the first time in the industry. A single 1.5mm diameter LED operated at 350mA has output 135 lumens (4730K) at 2.9V. In the industry silicon carbide and sapphire substrates used to create epitaxial wafer, but the materials and process are expensive. Bridgelux went with low cost gallium nitride, grown, wafers from 150 - 300 mm diameters, with a 75% reduction in cost, in comparison.

The Bridgelux CEO, Bill Watkins, has this to say about the tech, "The significantly reduced cost-structures enabled by Silicon-based LED technology will continue to deliver dramatic reductions in the up-front capital investment required for solid state lighting. In as little as two to three years, even the most price-sensitive markets, such as commercial and office lighting, residential applications, and retrofit lamps will seamlessly and rapidly convert to solid state lighting.”

We will see these emerge in 2-3 years.

Eavesdropper

Original bulb style lighting of the A44

LED illuminated A44

Philips has donated 294 high brightness LEDs to the Netherlands in conjunction with the RWS (Dutch Highway Authority the Rijkswaterstaat. Used to illuminate 17KM of the A44 highway, the SpeedStar LED solution is the first of its kind. Estimated to save 180,000 kWh per year, approximately energy consumption of 50 households, it saves over 40% of the energy that was used to light the highway's old lamps. “The aim for our collaboration with the Rijkswaterstaat is to implement lighting solutions that both save energy and require less maintenance work on the roads,” comments Frank van der Vloed, General Manager, Philips Lighting Benelux. “Together, we will help provide a safe night time driving experience while helping to lower energy consumption.”

Remote monitoring allows the installation to be dimmable, saving energy during slow periods, and brightened as traffic increases in the evening. Unfortunately, this section of highway is an experiment only at this time. I'm sure the trend will continue. When LEDs are good enough for car headlights, then it's finally bright enough for streetlights.

Eavesdropper

source Phillips PR

Realizing that consumers have long trusted the Energy Star brand for products that will save them energy and money, the two agencies responsible for the joint program, the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE), currently are taking steps to strengthen and improve it.

Last month, for example, EPA released the Final Draft of a new Energy Star product specification for Luminaires, intended to replace the Residential Light Fixtures (V4.2) and Solid State Lighting Luminaires (V1.1) specifications.

This spec has an effective date of October 1, 2011.

As before, excluded from the new specs are lighting products such as LED tube lights intended to replace fluorescent lamps and LED fixtures intended to replace linear fluorescent fixtures. Street area and parking garage lights are currently excluded from the Energy Star category but efforts are underway to include these product groups in the future.

As well as finalizing the Luminaires specification, EPA has been engaged in the revision of Energy Star program elements for all product categories, so as to meet third-party certification requirements which took effect on January 1, 2011.

Until this year Energy Star was a self-declaration program where manufacturers could submit their own test reports directly to EPA. Now, as of Jan 1, the EPA will require that all new submissions from manufacturers participating in the Energy Star program be reviewed by a third party Certification Body (CB), and that qualification testing be performed under specific criteria using EPA recognized labs. The certification body will review and send the report to EPA.

Laboratory test results must be produced using the specific models of LED package, LED module or LED array and LED driver (i.e. LED light engine) that will be used in production.

Follow up verification testing will have to be conducted annually on 10% of qualified products in the Energy Star program to insure a product’s continued compliance with the requirement after its initial qualification. Each CB will manage verification testing of the product they have certified.

These test reports center on IES (Illuminating Engineering Society) LM (Lighting Measurement) -79 (Electrical and Photometric Measurements of Solid State Lighting Products) and LM-80 (Measuring Lument Maintenance of LED Light Sources).

These tests detail such specifications as efficacy, luminous flux, chromaticity coordinates, intensity distribution, CCT (Correlated Color Temperature) and CRI (Color Rendering Index) values at all tested temperatures. Rapid cycle stress tests, temperature and electrical surge and transient protection across all SSL products are also included.

As an example consider LED light engine efficacy. Installed in the luminaire the source must now meet or exceed 65 lm/W per LED light engine (Until Sept. 1, 2013) and 70 lm/W per (after Sept. 1, 2013).

Similarly, Solid State LED packages, LED arrays or LED modules must meet the following L70 (Electrical and Photometric Measurements of Solid-State Lighting Products) rated lumen maintenance life values:

25,000 hours for residential grade indoor luminaires;

35,000 hours for residential grade outdoor luminaires; and

35,000 hours for commercial grade luminaires

There is also a mandatory 6,000 hour lumen maintenance test, which equates to about a 9 month duration. However, EPA understands that waiting 9 months can create economic hardships so manufacturers will be allowed to apply for a conditional early label option at 3,000 hours of testing when they supply LM 80 test data and in situ temperature test data. The conditional label is based on subsequent completion of the rest of the test.

The full Energy Star Luminaires specification is available from the Energy Star Luminaires web page, which also carries comments on Draft 1 of the specification (released May 10, 2010) and Draft 2 (released October 4, 2010).

Information on third party partners, Accreditation Bodies, Certification Bodies, and Laboratories can be found here.

Ford Kerosene Car Lamp

Calcium Carbide Car Lamp

Original automotive headlights burned kerosene, had a chimney, needed to be lit and extinguished.  Headlight innovations around the same time gave calcium carbide generators, with a controlled water drip, produced Acetylene Gas, which, when burned, produced intense light, greatly improving a car's nighttime vision. 

Today we don't have to re-fuel our headlights. Instead we enjoy LED lamps rated at 50,000 hrs, or 5 years of continual operation. In the past 2-3 years the industry has made great strides in integrating high performance LEDs in all vehicles. From side markers, to taillights, to the interior LEDs are becoming the standard. Like the LED lightbulb replacing standard bulbs, all auto lamps are headed to obsolescence.

The "holy grail" of automotive lighting has been to replace headlight lamps with an LED solution. A legitimate LED swap has been completely unheard of until now. The doors have flung open with the recent milestone in LED brightness output of 100 lumens per Watt, and further with some manufacturers demonstrating 200 lm/W in laboratories. Cars need over 800 lumens for proper headlight usage, and these LEDs are up to the task. For example, a single Cree XLamp XP-G Cree XLamp XP-G series LED can provide 400 Lumens at 1A and over 130 lm/W at 350mA. Driving the LED at 1A produces the maximum amount of heat, the number one issue with LED systems.

However, price has completely blocked the wide automotive adoption of LEDs. Just a few years ago, a single LED would cost $5.00 USD, in the past year has dropped to $1.00 USD. The sweet spot of price and ease of manufacturing should be hit in the coming 12 months. Despite initial cost, overall lifetime cost and environmental impact will over pay for itself. A regular halogen lamp, single beam, requires 55 watts (240 watts on high beam). The more efficient Xenon lamp needs 35 watts. Average power input need for LED lamps comes in at 28 watts per beam. The overall efficiency is only getting better. Volkswagen plans to introduce OSRAM Joule JFL2 LED systems into their headlamps promising only 19 watts per beam. Environmental impact also pushes adoption. On conventional cars, with LED lamps, 196 grams of carbon dioxide per 100Km (62 miles), compared to 768 grams per 100Km with halogen bulbs.

Plug-in and Hybrid vehicles benefit the most from LED lamp adoption. Up to 6 miles is added to a hybrid car's electric only range with the use of LED headlights. 19-28 watts is a far cry from the 55 - 240 watts needed with halogen bulbs. Toyota/Lexus was the first to offer LED lamps as an option, followed by Audi, Cadallac, and 2011 has most car manufacturers promising LED options. Most LEDs options are used for daytime running lights at the moment, but full beam implementation is close. As brightness levels increase and modules prices decrease, adoption for full headlight usage will become market standard. As of 2011, 3rd generation Toyota Prius, Nissan Leaf, and Mitsubishi i-MiEV will have full beam LED headlight options.

Efficiently driving and regulating an array of LEDs in a headlight is the main design difficulty. A few ICs are available now to drop right into the application. Linear Technologies has a DC/DC converter, LT3956, designed to operate as a constant-current and constant-voltage regulator, ideal for high brightness/high driving current LEDs. In particular, a 25 W white LED headlight lamp can be configures with 18 of the Cree XLamp XP Cree XLamp XP (130lm/W at 350mA) series elements. The LT3956 LT3956 outputs a PWM signal ranging from 100kHz to 1MHz, giving the user a dimmable ratio of 3000:1. Due to its tunable features, the LT3956EUHE#PBF LT3956EUHE#PBF is up to a 94% efficient. Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topology. However the 6% in efficiency, or 1.5W (25W*0.06), is dissipated as heat, even with the UHE package (5mm x 6mm) heat-sinking is inevitable.

Another option is the Renesas LED headlight driver, μPD168891, which can provide constant-current control for up to 12 LEDs in series. Renesas's IC has built in overcurrent protection, diagnostic functions, emergency shutoff to prevent current issues, and is in a 48-pin VQFN package to reduce heat generation.  A few others ICs exist, but no one chip is the end-all option in this fledgling industry. Choosing the right components is based on individual design requirements, and should be chosen accordingly.

A mere 100 years after the kerosene headlight, the automotive lighting has grown to be an over 10 Billion USD industry. Electrically efficient high lumen LEDs made it possible, and more of them are coming every quarter. With few components available in this relatively new automotive LED Lighting industry, the brave and the willing to get up to speed in a very short amount of time. Very few times in technological advances can someone start at the leading edge of an industry without extensive training. The building blocks are here, they just need someone to put them together.

Cabe

Personal automotive lighting design story:

I started in the automotive industry designing a side (turn) lamp systems for a future hybrid.  What I discovered is nothing more than V = I*R is needed for me to begin that career path. At first I was meticulous and cautions about power regulation, but eventually it came down to just matching a resistor to a LED ( R = V/I ). A later incarnation of my circuit used a driver IC like mentioned above, all I had was a datasheet. The prototype was finished and on its way to being part of the LED Auto Revolution. I will say with my first hand  experience, the industry needs more engineers.

The ‘Aurora in a Box’ which recreates the physics involved in the creation of the Northern Lights or Aurora Borealis, will be used to demonstrate how electrically charged particles in the atmosphere create the spectacle seen at the earth’s poles. Dr. Wild, a Physicist studying the space environment and the links between the Sun, the Earth and other planets, was awarded a grant from Research Councils UK to create the outreach tool to explain the research to non-specialist audiences. Dr Wild uses the model to help him explain his research to children in schools, at university events and at national science events. “For a start it’s just really interesting science, but it also has very practical uses. We use a lot of technology in space, like communications and positioning satellites, and those satellites are sometimes outside the protection of the Earth’s magnetic field. They’re therefore more vulnerable to changes in space weather and can be damaged or have their services disrupted. Being able to predict this would be very useful,” said Dr. Wild. The Aurora in a Box consists of glass tubes full of gas through which electrons move, causing the gas to fluoresce exactly as it does at the Earth’s poles. Auroras are linked to the solar wind, a flow of ions and electrons continuously flowing outward from the Sun. The Earth's magnetic field traps these particles, most of which travel toward the poles where they are accelerated towards the Earth. Collisions between these particles, and atmospheric atoms and molecules, causes energy releases in the form of streams or arches of colored light.

Zero