Ultrathin Inorganic LEDs

There is now a new process under development to create ultrathin, ultrasmall inorganic light-emitting diodes (LEDs) and assembling them into large arrays, which offers new classes of lighting and display systems with interesting properties.

Applications for the arrays, which you can print onto flat or flexible substrates ranging from glass to plastic and rubber, include general illumination, high-resolution home theater displays, wearable health monitors, and biomedical imaging devices.

“Our goal is to marry some of the advantages of inorganic LED technology with the scalability, ease of processing, and resolution of organic LEDs,” said John Rogers, the Flory-Founder chair professor of Materials Science and Engineering at the University of Illinois.

Compared to organic LEDs, inorganic LEDs are brighter, more robust, and longer-lived. Organic LEDs, however, are attractive because you can form them on flexible substrates, in dense, interconnected arrays. The researchers’ new technology combines features of both.

“By printing large arrays of ultrathin, ultrasmall inorganic LEDs and interconnecting them using thin-film processing, we can create general lighting and high-resolution display systems that otherwise could not be built with the conventional ways that inorganic LEDs are made, manipulated, and assembled,” Rogers said.

To overcome requirements on device size and thickness associated with conventional wafer dicing, packaging, and wire bonding methods, researchers developed epitaxial growth techniques for creating LEDs with sizes up to 100 times smaller than usual. They also developed printing processes for assembling these devices into arrays on stiff, flexible, and stretchable substrates.

As part of the growth process, a sacrificial layer of material embeds beneath the LEDs. When fabrication is complete, a wet chemical etchent removes this layer, leaving the LEDs undercut from the wafer but still tethered at anchor points.

To create an array, a rubber stamp contacts the wafer surface at selected points, lifts off the LEDs at those points, and transfers them to the desired substrate.

“The stamping process provides a much faster alternative to the standard robotic ‘pick and place’ process that manipulates inorganic LEDs one at a time,” Rogers said. “The new approach can lift large numbers of small, thin LEDs from the wafer in one step, and then print them onto a substrate in another step.”

By shifting position and repeating the stamping process, LEDs can transfer to other locations on the same substrate. In this fashion, you can create large light panels and displays from small LEDs made in dense arrays on a single, comparatively small wafer. And, because the LEDs can be placed far apart and still provide sufficient light output, the panels and displays can be nearly transparent. The thin device geometries allow the use of thin-film processing methods, rather than wire bonding, for interconnects.

In addition to solid-state lighting, instrument panels, and display systems, the new method also allows for flexible and even stretchable sheets of printed LEDs, with potential use in the health-care industry.

“Wrapping a stretchable sheet of tiny LEDs around the human body offers interesting opportunities in biomedicine and biotechnology,” Rogers said, “including applications in health monitoring, diagnostics, and imaging.”

LED Backlighting

It is said that energy-saving flat-panel television sets are about to become common in shops, spawning a whole new range of technical words to understand in Berlin.

Most manufacturers believe the best way to reduce TV power consumption is to change the type of lamp at the back of the flat panel, as well as to devise clever ways to reduce wasted light output.

The newest liquid-crystal-display (LCD) television sets are to feature LED backlights instead of the cold cathode fluorescent lamps (CCFL) which have done the job in the past. LED stands for light- emitting diode.

That is where the confusion starts, because at the same time, the electronics industry has been trying, without much success, to develop TV-sized displays where the image itself is formed by a matrix of LEDs.

LED backlighting has got nothing to do with that technology: all it changes is the light source that shines through the LCD screen.

Word has been spreading for a decade that LED light bulbs are more efficient than fluorescent lamps, so it is no surprise that TV manufacturers are also turning to this new light source.

Philips, for example, claims an energy saving of 40 per cent on its televisions.

The different ways of configuring this new type of backlight are sure to set off more confusion.

The simplest way to deploy the LEDs is around the four edges of the screen and let the light diffuse across the back of the screen. This is cheaper, and salespeople will make a point of explaining that these ‘edge-lit’ displays are even thinner than their predecessors.

‘For the bigger screens, this requires about 500 LEDs,’ explains Peter Koch of LG Germany.

More expensive are the so-called direct LED backlights. Instead of being placed around the edges, these LED lamps are arrayed right across the back of the screen. Direct-LED backlighting is a smart idea because the intensity of the light can be dimmed behind dark parts of the image. This ‘local dimming’ creates deeper, more natural blacks.

‘If the image is of people under a night sky,’ all the LEDs behind the sky will be turned off so that it really seems dark,’ explains Sascha Lange of Toshiba Germany.

This matters, because LCD televisions are often thought to be a degree inferior when compared to plasma flat-panel televisions. The black on existing LCD screens is generally a dark grey, and colours generally seem washed out when viewed off-centre.

Over time, local dimming also helps to save electricity and keep the TV set cooler.

The new backlights generally use LEDs that give off white light, but there is a third variant, the so-called RGB backlight system, which uses a mixture of red green and blue LEDs.

This will only be offered in the most expensive sets, aimed at buyers who want the very best. In fact, television broadcasts do not demand such a subtle graduation of colours, but the difference will be visible while watching the highest-quality high-definition films from Blu-ray discs.

Do You Want to Make Your Bath Time More Fun?

We have always marveled at the simplicity and the beauty of the new shower head, which uses LED lights to give it an extra charm and makes the cleaning up time more colorful and fun, especially great for kids.

I haven’t really seen anything like this, and I think it is quite amazing. Using this shower, bath time will never be dull again, whether you are 3 years old, or you are 80. There are four different colors that appear on the shower, illuminating the water.

These lights are not just really cool to look at, but also have a certain level of practicality associated with them. The color of the LED light changes with temperature, and so if you have really hot water coming out of the shower, the lights glow red,and the color automatically changes with any fluctuations in temperature, going through yellow and blue and finally green for really cold water. This really helps because you will no longer have to test the water temperature before you step into the shower, and you can adjust the water accordingly until you reach the color that you want to.

The best part is you don’t need any additional batteries to operate the lights, they are powered by the water pressure, and this makes it an eco-friendly option. The shower head is also just the right size, very easy to install (just unscrew your old shower head and replace it with this one) and very sturdy, having been made with ABS plastic. They fit on to the standard shower pipe size, and so they are suitable for almost every bathroom.

This is most definitely the perfect accessory to make bath time more romantic, or even to entice your kids into showering. It is said that its price is around $67, so I think it isn’t even too expensive to consider, right?

New High Performance LED Lighting Systems

It is reported that AeroLED sponsored a media lunch today at AirVenture 2009 to introduce their new line of high performance LED lighting solutions. Based on super-bright LED technology, which is fully replaceable with original lighting systems, pronounced “aerolead” the company produces retrofit and OEM lighting options.

Nate Calvin of AeroLED reported the company’s product is a direct replacement for existing incandescent, or “legacy systems” products now in the field, including a replacement for the GE 4509 landing light bulb. Components include options for replacement of navigation and strobe units as well.

Calvin said all components exceed FAR requirements for lumen output. Stating that incandescent systems operate in the 2500 Kelvin range whereas the AeroLED product operates in the 6500 Kelvin range, providing a more white colored and intense light output. The lighting is directional for the strobe application, more closely matching the diminishing requirements from horizontal to vertical plane of the FAR’s. The units are also on the order of 4 times lighter than traditional systems with significantly lower amperage draw.

Initial products were offered to the experimental and homebuilt markets to facilitate a positive cash flow and to support FAR 23 and TSO testing requirements for certified systems. An added benefit to this business approach was the opportunity to receive feedback from the initial customer base. AeroLED also allowed OEM customers to provide opinions for improvements. Calvin stated that all the feedback was considered key to current product line development, resulting in a superior product.

The Pulsar series is the first all LED nav and strobe light combination according to Calvin. The units are ruggedly constructed having gone through complete and thorough vibration and abuse testing, including installation on aircraft equipped with diesel engines that destroyed incandescent bulbs in as little as 10 hours. The units are hermetically sealed and are displayed under water to demonstrate their durability for all weather operation. Calvin quipped that the underwater display was a bit “cheesy” but proved to be an eye catcher and brought people over to investigate. Testing on the units has indicated a life expectancy of around 60,000 hours, well beyond most airframe lifetimes. While not specifically stating a price for the components, Calvin said they were comparable to costs of traditional lighting systems when replacement bulbs and power supplies over the life of the aircraft were factored in.

All AeroLED units have built in overtemp protection and offer very low RF emmisions and will not interfere with radio operations. Operating on 9-36 volts the systems do not dim, as incandescent lights do, at lower voltage levels and deliver the same lumen output regardless of input voltage.

AeroLED is committed to providing a see and avoid product. The company believes, and is receiving encouraging reports, that their system allows much greater visibility at a longer range than any other system currently available. All systems have wigwag capability allowing spotting far in advance of typical legacy systems and AeroLED systems are more visible in daytime than other systems. PMA certification is expected by year end.

Mini LED Camping Light

A camping lantern, nicessity for home use or car camping or backpacking alike, which is so small and light it fits right on your keychain via a carabiner. Weighing under an ounce and measuring one by two inches, the LED Mini is a perfect back-up light. Throw this in your pocket and forget all about it until the sun dips below the craggy peaks and darkness engulfs you. Then turn it on and light up your tent; though it’s small, it outputs 3.5 lumens and is supposedly capable of lighting up an entire tent. Luckily, since it’ll be most at home in the backcountry, it will likely just have to provide enough juice for a slimmed-down, ultralight solo or two-man.

If you find yourself in a sticky situation where mere light simply won’t bail you out, the LED Mini also includes a strobe setting for catching the attention of other campers. It can run continuously for 25 hours (or 50 on strobe) with the two included 3 volt CR2032 batteries. It may not provide a spotlight for your acoustic guitar solo, but for $6.99 it’ll certainly be a valuable addition to your gear closet.

The Kast LED Task Light

The beautiful, sleek, yet simple design of the Kast light is complemented by its quarter-shaped array of two five-watt LED clusters which are precisely angled to deliver glare-free light projection.

Kast has been manufactured with sustainability in mind, using over 80 percent recyclable aluminum and steel, composed of 40 percent recycled material with 27 percent post-consumer recycled content, and 100 percent solvent free powder coat finishes. The LED light helps make the task light affordable to the user, offering an average rated life of 100,000 hours which is ten times greater than most compact fluorescent lamps. In addition, the LED diodes are nearly 25 percent more energy-efficient than comparable compact fluorescent technology.

This is the first year for the Green GOOD DESIGN Award. It is a specialized edition of the GOOD DESIGN Award program which was founded in 1950 by architects Eero Saarinen, Charles and Ray Eames, and Edgar Kaufmann Jr. The GOOD DESIGN Awards bestow international recognition on designers and manufacturers for advancing innovation and originality. The awards are presented by The Chicago Athenaeum: Museum of Architecture and Design and the European Centre for Architecture Art Design and Urban Studies.

The purpose of the Green GOOD DESIGN Award is to emphasize the importance of sustainable design and to develop a public awareness program to the international general public educating about which companies are doing the greatest job creating sustainable design for our world environments. The Green GOOD DESIGN Award received hundreds of submissions from over 40 nations. Only 105 products, programs, people, government, environmental planning, and architecture were selected as outstanding examples of Green Design.

The Kast(TM) LED task light by Details, a Steelcase company, recently received a 2009 Green GOOD DESIGN(TM) Corporate Award. This award sets the bar for outstanding examples of Green Design. The beautiful, sleek, yet simple design of the Kast light is complemented by its quarter-shaped array of two five-watt LED clusters which are precisely angled to deliver glare-free light projection.

Multi-chip LED Belt out up to 2,000 Lumens

It is said by LedEngin (a US LED company) that the high flux LED gives the brightest 40W light source with the highest light output and flux density for architectural and general lighting applications.

The LED light source has a thermal resistance of 0.7 C/W, and the company claims, is brighter than the competition by between six to 10 times.

The company is also offering 24 and 35 lenses optimized for the LED and mazimizes the light with uniform color. LedEngin says that there are no shadows or fringe effects that other lenses offer.

The 40W LED and lenses are available now, and the company is sampling them on a custom MCPCB for easier installation and alignment with the lens and lens holder.

Test on SAMSUNG LED TV B7000

LED is a kind of tiny light-bulb like those we use as break light at the rear of the BMW or Mercedes. Compare to the former CCFL Cold cathode fluorescent lamp on LCD TV, the LED light is brighter, no heat, last longer and more energy efficient. Samsung has incorporated an LED light-source in order to accentuate a deeper black, more dynamic contrast, enhanced visual fidelity and definitely the inevitable charm of slimmer panel design.

4 Picture Mode (Dynamic / Standard / Natural / Movie)

Black color variation range to bright white is nicely detailed.

Sorry Mr. Bond but your wrinkle is clearly countable due to glass panel.

Great depth and color vibrant.

Picture quality is so high that we can read out the multiple choice selections.

The LED Streetlights Could Drive You Crazy and Make You Fat?

This is a test on LED streetlight. During the day, the block of bungalows and houses at 22nd Avenue East and East Mercer Street looks like most of Capitol Hill. But at night, it looks crazy. This is one of seven test areas in the neighborhood where Seattle City Light swapped the high-pressure sodium streetlights, which emit a warm orange hue, with glaring LEDs. City officials want to replace all 40,000 residential streetlamps in Seattle with the new light-emitting diodes by next year to save energy and money. But the lights cast a sickening hue. “It is a very cold color—zombie blue,” says Dan Travers, who lives on the block. “My first thought was that people are going to look scary under these lights.”

“It looks like you are in a supermarket aisle,” says Andie deRoux, who lives in an apartment building seven blocks west of Travers. Abby Katzman, who has lived on the eastern slope of Capitol Hill for 20 years, says, “I like the energy it saves, but it does seem very cool and wintery.”

On the shortest night of the year, just after dark at 11:00 p.m., I walked to each of Seattle City Light’s test areas to see what’s sparking revulsion from Travers and others who live under the lights. The beams from the high-intensity, light-emitting diodes are striking. The rays turned my skin the color of white taffy and cast crisp shadows on the pavement. “Zombie blue” is exactly right: Like a day-for-night special effect in a vampire movie, the test streetlights create the sort of atmosphere where you almost expect the undead to emerge from the flower beds and begin eating your face. Everyone I spoke to enthusiastically supported the idea of the LEDs—which require 50 to 60 percent less electricity for the same lumens—but most resented the quality of the light itself.

The problem with the new lights isn’t just aesthetic. According to Dr. David Avery—a professor of behavioral sciences and light therapy at the University of Washington and the region’s leading researcher on the impact of light on human chemistry—the LED lights could interfere with human biorhythms. Certain photoreceptors in the eye’s retina react to cooler colors of the light spectrum, sending a signal to the brain that the sun is up. When humans see the blue light, our bodies think it’s daytime. “The sensitivity to these cells for the blue and greenish color makes perfect sense, because the sky is blue. So for millions of years, life has evolved with this 24-hour rhythm of blue light being very prominent for part of the day and then darkness,” he says. “This is kind of a conductor of a circadian symphony in the brain and body.”

According to Avery, “Theoretically, if someone has one of these LEDs or a blue light outside their window, it could fool the eyes and the brain into thinking that the sun is still up, so the melatonin hormone might not rise normally and sleep might be disrupted.” Incandescent lights, the standard bulb in homes, are on the red end of the spectrum. (You may think of them as being white, but they’re not.) Shifting the city’s primary outdoor lighting to blue-hued LEDS, Avery adds, “would be a major change in terms of our environment.” Studies suggest that people exposed to daylight at the wrong hours, like those who work night shift, have more health problems such as high blood pressure and obesity, Avery says.

Mayor Greg Nickels wants most Seattle residents to be living under new streetlights by 2015. Seattle City Light intends to install the lights specifically in residential areas—not commercial arterials or industrial zones, which require more illumination than LEDs can affordably provide.

“They would save about nine million kilowatt hours and about $408,000 a year,” says Seattle City Light spokesman Scott Thomsen. An LED lamp uses only 50 watts, while traditional high-pressure sodium bulbs require 130 watts and waste electricity on heat. The conserved power roughly equates to the energy used by 750 single-family houses a year, Thomsen says. Moreover, the LED lamps last three to four times longer—up to 18 years—which drastically reduces maintenance costs to the city. (The city currently pays about $100 in labor costs to replace each dead bulb.)

But LED fixtures cost much more. Whereas the bulbs in the existing fixtures (awesomely dubbed “cobra heads”) cost about $15, the LED lamps are part and parcel with their fixtures and each costs $300 to replace, says Edward Smalley, Seattle City Light’s streetlight engineering manager. “The real payout for the city, to the customer, is not having to go out to change the light.” Funding to kick-start the program comes from a $6.1 million federal stimulus grant to reduce energy use. Of that, $1 million will go toward installing the first 2,500 streetlamps next year, assuming the Department of Energy approves the expenditure this summer. If the city council expands the program, new streetlamps citywide will cost about $20 million.

City officials acknowledge the test lights aren’t great. (A different brand of LED is being tested at each site, or in some cases the same brand at different levels of brightness.) Although some people like the lights, other people in the test areas have been complaining—in one area, the reaction from residents has been so intense that Seattle City Light is canceling that test site. And it is continuing to look for better technologies. There’s a relationship between a light’s warmth and how much energy it saves. High-pressure sodium lights, which give off that night orange glow, emit light at about 2200 degrees Kelvin. But the pilot LEDs are between 5000 and 6000 Kelvin. While Smalley acknowledges the new lights are “a lot bluer, for sure, than what we have now,” LEDs as warm as the old lights aren’t energy efficient enough to be practical. Seattle City Light will begin testing slightly warmer-hued streetlamps in Seattle’s South Park neighborhood in late July. “We are looking at 4000 degrees Kelvin and above, so that way we can provide the best comfort for the city and the energy savings that we are looking for.”

Anchorage has begun installing 16,000 LEDs streetlamps, San Francisco has announced it will convert 30,000 streetlamps, and Los Angeles has announced plans to convert 140,000 lamps. Smalley says that technology to produce energy-efficient LEDs with a more palatable hue is evolving, with new generations of lights emerging as quickly as every six months.

Considering the bulbs live longer than most pets, the city should take as much time as necessary to pick a light we can live with for a while. Smalley said that those folks who dislike the lights, stay tuned and look to our next test sites like South Park. No one has locked into what you see out on the street now.

The First Purely White LED Produced in Korea

It is claimed from Korea Researchers that the world’s first purely white LED (light-emitting diode) has been produced in Korea.

Soo-Young Park, a professor of organic materials for photonics at the Department of Materials Science and Engineering at Seoul National University in Korea, led the group, which includes researchers from the University of Valencia in Spain.

LEDs are much more energy-efficient than incandescent or compact fluorescent lightng (CFL), but the quality of light they can give a room is up for debate.

Because LEDs do not naturally produce white light, getting them to look like they do adds to their production cost, making them much more expensive than your average incandescent or CFL. Many companies have been trying to come up with different LED recipes and components to produce a nice white light, while keeping the consumer cost down.

Park and his group claim to have engineered a molecule with one orange and one blue light-emitting material that produces a white light in the visible light spectrum when put together.

In other words, they say they’ve invented a white-light-emitting diode.

Repeated laboratory tests apparently showed that the new form of LED molecule is efficient, color stable, and able to be reproduced again and again, making it a legitimate candidate for use in LED lighting.

A detailed explanation of the group’s molecular work can be found in the current issue of Journal of the American Chemical Society.

According to Mr.Park and his group in their paper, an ideal material for a white-light source should be cost-effective, stable, robust, emit over the whole visible spectrum, not suffer from self-absorption, and its pure color should be easily reproducible. With this goal in mind, we have successfully synthesized and characterized, for the first time, a white-light-emitting single molecule dyad, consisting of two noninteracting chromophores showing excited-state intramolecular proton transfer.