North America

A Way to Boost Light from OLEDs

sarafan — Wed, 23 Jul 2008 06:07:34 +0000

Energy efficiency and flexible lighting applications of OLEDs hasn't lived up to its promise, however, because in typical OLEDs, only 20 percent of the light generated is released from the device. That means that most light is trapped inside the bulb, making it highly inefficient.

It's reported the scientists are on to a way to break the OLED-efficiency logjam. TThey have designed an OLED that boosts illumination by 60 percent using a combination of an organic grid working in tandem with small micro lenses that guide the trapped light out of the device.

Generally, In OLEDs, white light is generated by using electricity to send an electron into nanometer-thick layers of organic materials that behave like semiconductor materials. Typically, the light in the substrate is internally reflected and runs parallel and not perpendicular. That's the crux of the problem because the light can't escape in the vertical direction without some coaxing. In Forrest's devices, the grids refract the trapped light, sending it to the five micrometers dome-shaped micro lenses. The light is sent off in a vertical orientation that helps release the trapped rays.

According to the expert said the technology emits about 70 lumens from a watt of power. In comparison, incandescent lightbulbs emit 15 lumens per watt. Fluorescent lights put out roughly 90 lumens of light per watt but have liabilities: they produce harsh light, lack longevity, and use environment-damaging substances like mercury.He says that the next step in the research is to use OLEDs that are more efficient than those the team used in the current project. Looking beyond the research lab work on these OLEDs, he is cautiously optimistic that it should be possible to scale up the manufacturing of the devices, and that production costs for manufacturing the new OLEDs will be competitive.

Now, an estimated 22 percent of the electricity produced goes to lighting buildings. A highly efficient form of OLED lighting could significantly reduce the electricity demand and boost savings. Another factor influencing broad adoption of LEDs is the fact that they outlast incandescent bulbs. Over the next 20 years, the rapid adoption of LED lighting in the United States could reduce electricity demands by 62 percent and thus eliminate 258 million metric tons of carbon emissions, according to the Department of Energy.

New Breakthrough Allows LED Lighting to be Processed on Silicon at Low Cost

sarafan — Tue, 22 Jul 2008 08:49:21 +0000

It's reported Purdue's Professor Sands and a graduate researcher man the reactor, which produces the first blue LEDs based on a silicon process. The new LEDs promise greater efficiency, longer lifetimes, and much lower costs. Purdue research have developed new production methods which will cut LED lighting costs to about a twentieth of current expenses.

Recently, The U.S. Department of Energy announced a $20M USD "L Prize" for the first solid-state lighting meeting a strict standard of criteria. While the prize sounded very intriguing because solid-state lighting on the market today falls short of the requirements by a sizable margin. However, a new breakthrough in processing from the Purdue University may change all of that. Researchers at Purdue have developed a technique to manufacture LED solid-state lighting at great savings using metal-coated silicon wafers.

The light-emitting layer of an LED light is a gallium nitride crystal in traditional. In sapphire based LEDs, used for green or blue lighting, mirror-like reflectors are need to reflect and resend emitted light, increasing the efficiency. Typically, this layer is extremely expensive to produce, part of the reason the current generation of LED lighting costs so much, costing at least 20 times more than conventional incandescent and fluorescent bulbs. Also, the LEDs are built on sapphire crystals, which provide the color, but are extremely expensive. The method uses aluminum nitride to provide the tint.

Now LEDs use a layer of zirconium nitride to provide the mirror effect. Normally, zirconium nitride reacts with silicon, making a silicon process difficult. However, by isolating the zirconium nitride with a protective layer to prevent reaction, scientists are able to fully deposit the need layers, including the gallium nitride necessary to build a full LED.

With the advance, for the first time the LEDs will be able to be produced on standard silicon wafers. The new wafers can be made using cheap existing processes. To deposit the colored layer, reactive sputter deposition is used. Aluminum is bombarded with positive Argon ions, which send it flying out into the air, reacting with nitrogen gas and being deposited on the silicon. For the zirconium reflective layer, an identical process is used with zirconium metal in place of aluminum. The final gallium layer is deposited using organometallic vapor phase epitaxy; a common deposition technique performed using high heat.

The new techniques yield a crystalline structure aligned to the crystalline silicon. This means that the LEDs are less prone to defects and will perform more efficiently. Further, by using common techniques costs are dramatically reduced from using more expensive alternative methods like crystal growth on glass using sapphire crystals. Another advantage is that silicon dissipates heat more effectively than sapphires. This will reduce damage during operation and lead to longer lifetimes and more reliability. The new device is extremely promising as it may allow lighting to finally do primarily what it was intended -- make light. Traditional incandescent bulbs are better heaters than lights, wasting 90 percent of energy as heat. LEDs currently on the market have efficiencies from 47 to 64 percent of energy converted into light, with the Purdue design expected to fall on the high-end of this range.

Professor Sands expects the process to be commercially adopted and operating within two years. A final hurdle for it to overcome is a problem with the gallium nitride layer cracking during cooling. He believes this problem will soon be solved, though, with a bit more research. He states, "These are engineering issues, not major show stoppers. The major obstacle was coming up with a substrate based on silicon that also has a reflective surface underneath the epitaxial gallium nitride layer, and we have now solved this problem."

Cree expects the production costs of LED lighting to drop fast

sarafan — Tue, 22 Jul 2008 08:28:43 +0000

Cree expects LED lighting production costs to drop fast, coming close to the levels of fluorescent lamps by 2012. XLamp MC-E has been widely adopted by clients for commercial lighting, flash lights, street lamps and others.Cree showcased its XLamp MC-E LED lighting solution at a demonstration it jointly arranged in Taipei with IC distributor WP Industrial (WPI), a subsidiary of WPG Holdings. WPI displayed driver ICs and related solutions for LED lighting. Cree mentioned, the XLamp MC-E LED is a lighting-class multi-chip LED that provides four times the flux as XLamp XR-E in the same footprint, without compromising thermal performance. XLamp MC-E reduces LED system cost by reducing system complexity and the number of components required.

Low-cost, silicon-based LEDs should be on the market within two years

sarafan — Mon, 21 Jul 2008 08:55:34 +0000

The technique overcomes prohibitive costs of current LED technology by building the diodes on low cost silicon wafers, instead of currently-used sapphire.

LEDs are said to be four times more efficient than conventional incandescent lights, more environmentally friendly than compact fluorescent lights, and have a far longer lifespan of up to 15 years.

According to Purdue University researchers who developed the technique, LED technology could cut electricity consumption by 10 percent if widely adopted. Timothy D. Sands, the Basil S. Turner Professor of Materials Engineering and Electrical and Computer Engineering said "If you replaced existing lighting with solid-state lighting ... it could reduce the amount of energy we consume for lighting by about one-third."

Sands described currently-used incandescent bulbs as heaters, explaining that they convert only 10 percent of electricity into light, and the rest into heat. In comparison, LEDs designed to emit white light operate at efficiencies ranging from 47 to 64 percent, but cost around 20 times more than conventional incandescent and compact fluorescent light bulbs.

Current LEDs are built on sapphire and comprise of a light-emitting material called gallium nitride and a costly mirror-like collector to reflect light that ordinarily would be lost.Researchers expect the use of silicon to enable the industry to "scale up" the process, or manufacture many devices on large wafers of silicon, which is not possible using sapphire. Sands said Producing many devices on a single wafer reduces the cost.

Another advantage of silicon is that it dissipates heat better than sapphire, reducing damage caused by heating, which researchers expect will improve reliability and increase the lifetime of LED lighting."When the cost of a white LED lamp comes down to about $5, LEDs will be in widespread use for general illumination," Sands predicts. "LEDs are still improving in efficiency, so they will surpass fluorescents,」 he said. 「Everything looks favourable for LEDs, except for that initial cost, a problem that is likely to be solved soon."

Affordable LED lights should be on the market within two years, he expects.

Avnet Expert to Keynote at 2008 LED Technology Investment Forum

Emma — Tue, 13 May 2008 03:20:10 +0000

According to Avent, Eskow is a twenty-seven-year Avnet veteran who holds two industry patents and will present On the Shoulders of Edison a view of the current state and future opportunities for solid-state lighting (SSL) using light emitting diode (LED) technology.

In one sense, we're all at the leading edge of the solid state lighting revolution, said Eskow. To date the impetus has been improved energy efficiency, but the true innovators will go beyond efficiency and leverage LED-based lighting's potential to positively impact the quality of life in many segments, ranging from improving a surgeon's acuity in the operating room to enhancing the visual appeal of merchandise by managing the color temperature of white light. The horizons for LED-based lighting are nearly limitless.

One-on-one discussions with investors will follow Eskow s address and the question and answer session.

New Industrial LCD Panels With Long-Life LED Backlighting Systems From Toshiba America Electronic Components

Emma — Tue, 13 May 2008 03:17:57 +0000

TFT LCD Modules Feature Replaceable LED Backlights, High Brightness and Low Power Consumption

Toshiba America Electronic Components, Inc., a committed industry leader that collaborates with customers to create breakthrough designs, today announced a new color active-matrix thin-film transistor (TFT) liquid crystal display (LCD) module product lineup for industrial applications that incorporates long-life light-emitting diode (LED) backlighting systems. Developed by Toshiba Matsushita Display Technology Co., Ltd. (TMD)**, the modules are designed to satisfy the requirements of a broad range of industrial applications, such as test and measuring equipment, medical equipment, portable handheld computing devices, and more, utilizing the latest LED backlighting technology.

The series includes five new LCD products: 5.7-inch QVGA 320 x 240, 6.5-inch VGA 640 x 480, 8.4-inch SVGA 800 x 600, 8.4-inch 1024 x 768, and 10.4-inch XGA 1024 x 768. All the products have replaceable, long-life, LED-based backlighting systems, and are designed such that a resistive touch panel can be added as an option.

"These new, leading-edge LED-backlit modules are an important addition to our line-up and address a growing demand in a wide variety of industrial LCD applications," said Sean Collins, vice president business development, Display Devices and Components Group, for TAEC. "TMD continues to demonstrate a long history and commitment to the industrial market by providing displays that feature high brightness, wide viewing angles, wide operating temperature ranges, and replaceable backlighting structures. The addition of these new LED long-life product will bring clear and further benefits to industrial system designers."

The LED-based backlighting systems provide an average backlight lifetime of 70,000 hours, or approximately 8 years continuous operation, (to half-brightness of the initial luminance specification), which exceeds that of today's common TFT LCDs for industrial applications utilizing long-life cold cathode fluorescent lamp (CCFL) backlighting systems. TMD has achieved this by applying long-life LEDs, and by optimizing the thermal design of the industrial-type LED-based backlighting system based on TMD's extensive experience in utilizing LED backlighting for mobile notebook PC TFT displays. The modules have been designed with a replaceable backlight structure to accommodate the product longevity requirements, and the harsh-usage environments, of industrial applications. In addition, TMD has added the LED driver circuitry into the electrical interface for the displays, an added benefit for customers to simplify their design-in time and costs.

Compared to CCFL backlit displays, LED-backlit displays feature superior characteristics such as lighter weight, lower electrical noise, lower power consumption, and offer a wider adjustable luminance range. LED-backlit displays also reduce the environmental impact, in consideration of both material and energy consumption, since they are mercury-free(1) and lower in power consumption. Also, the new LED-backlit displays do not require the high-voltage and high-frequency circuits required to control luminance in CCFL-backlit displays, thus enabling a higher level of flexibility in system design in terms of safety, electro-magnetic interference (EMI) compensation, and system architecture.

These newly developed products will be exhibited by TMD at the 11th Embedded Systems Technology Expo & Conference (ESEC), booth #EAST35-15, to be held at Tokyo Big Sight, Tokyo, Japan, May 14-16, 2008, and by Toshiba America Electronic Components at the 2008 Society for Information Display International Symposium, Seminar and Exhibition, booth #135, to be held at Los Angeles Convention Center in Los Angeles, CA, USA, May 20- 22, 2008.

LED rings in the IR spotlight

Emma — Mon, 12 May 2008 06:32:32 +0000

The OPA80 Series and OPA83 Series from Optek Technology are available in a variety of ring sizes and configurations, and feature an optional ambient light sensing device to minimise current consumption during high ambient light conditions "The OPA80 and OPA83 Series light rings were designed to easily illuminate a specific area with infra-red light", says Roland Chapa, Vice President of Optek Technology's Assemblies Business Unit

"With a variety of configurations and sizes, along with the option for reduced current consumption, the light rings are ideal for applications ranging from mood lighting to daylight security camera lighting".

Additional applications for the near-infra-red light rings include spot lighting, flash lighting and under-counter lighting.

The near-infra-red light ring series includes the OPA80 12V light ring with ambient light sensor; OPA81 12V light ring without sensor; OPA82 5V light ring with ambient light sensor; and OPA83 5V light ring without sensor.

LED quantities range from 10 to 24, depending on voltage rating and ring size.

LED types include surface mount devices, with a viewing angle of 100 degrees, as well as 3mm through-hole packages with viewing angles of 18 degrees.

The OPA80 and OPA83 Series light rings are available in either 850nm or 880nm centre wavelengths.

Typical forward voltage for each LED is 1.35V.

Reverse voltage per emitter is 2.0V, with a continuous forward current of 50mA and peak pulsed forward current of 1.0A at 1% duty cycle.

Operating temperature ranges from -40 to +85C.

Custom mounting, electrical, cabling and connectors are also available.

The light rings are RoHS-compliant.

Typical pricing for the OPA80 and OPA83 Series light rings starts at US $11.75 each in quantities of 1000.

Lead time, if stock is not available, is from 6 to 8 weeks

RGB-LED Development Board Includes Wireless Remote

Emma — Mon, 12 May 2008 06:25:26 +0000

Addressing the high level of interest in solid-state lighting, TPS62260LED LED develoipment board from Texas Inatruments enables lighting designers to develop and evaluate a variable-color RGB-LED lighting system using an RF lighting control for management of lighting intensity and color. The board combines three OSRAM high-brightness LEDs (red, green and blue) with an MSP430F2131 microcontroller to control the brightness of each LED using the output of three dedicated TPS62260 solid-state lighting drivers (SSLD).

The eZ430-RF2500 development tool plugs directly onto the board to allow designers to create a lighting network of RF-controlled lamps. The design module is also pin-compatible with TPS62240 buck converters for lower-current applications such as indoor ambient lighting and the TPS62290 for higher-current applications such as wall washing. The TPS62260LED board is available today at a suggested resale price of $19 and includes a populated and pre-programmed MSP430 microcontroller, plus board documentation. Additionally, the eZ430-RF2500 development tool can be ordered for $49.

Acuity inks LED pact with Lighting Science Group

Emma — Mon, 12 May 2008 03:36:53 +0000

Acuity Brands Lighting Inc. has forged a relationship with Dallas-based Lighting Science Group Corp. (OTC BB: LSCG) to develop and sell multiple light emitting diode (LED) lighting products.

The products will be added to the Acuity Brands Inc. (NYSE: AYI) unit's portfolio, which includes Lithonia Lighting, Holophane, Hydrel and Gotham. The products will be for architectural, commercial, industrial, and public infrastructure use.

"This alliance with Lighting Science Group allows Acuity Brands Lighting to enhance its existing LED portfolio using advanced technology," said Vernon J. Nagel, chairman, president, and CEO of Atlanta-based Acuity Brands. "We continue to seek out strong alliances to accelerate our ability to integrate advanced technologies, such as LED, into leading edge fixture design to serve specific customer needs. LSG's patented technology, experienced management team, and expertise in thermal management, driver design, and color control will give us a broader product offering for the growing LED market."

Acuity said LED light sources can sometimes surpass traditional technology in energy efficiency, fixture life, and environmental impact. LEDs consume up to 80 percent less energy than traditional incandescent sources and as much as 50 percent less energy than compact fluorescent lamps.

AXT to Present at the 2008 AmTech Research LED Technology Investment Conference

Emma — Mon, 12 May 2008 03:25:26 +0000

AXT, a manufacturer of compound semiconductor substrates, announced that Robert G. Ochrym, Vice President of Business Development, will present at the American Technology Research 2008 LED Technology Investment Forum at the New York Palace Hotel in New York, NY on Thursday, May 15th, at 9:30 a.m. ET.

Ochrym will address the requirements and outlook of gallium arsenide (GaAs) semi-conducting substrates for the LED industry.

A copy of his presentation is available on AXT's website, the company noted in a release.