If you haven’t noticed, lighting is undergoing a quiet revolution that may ring the death knell for light bulb jokes.
By now, everyone is familiar with high-intensity LED flashlights, LED automotive brake lights, and solid-state emergency lamps. It’s plain there are fundamental changes happening that are as revolutionary as the cold-cathode fluorescent lamp itself.
In the realm of multi-color LEDs, there's a lot of activity. We recently
reported on Osram’s nifty MultiLEDs. Another company making clever illumination products is
Luminus Devices.
Luminus’ PhlatLight solid-state light sources combine LED and laser technologies. Unlike garden variety LEDs that emit light through epoxy encapsulants, these LEDs emit light directly.
Why are they called PhlatLights? The somewhat implausible moniker is actually derived from the two words
photonic and
lattice.Arc Lamp SubstitutesPhotonic lattice surface light emission makes for large-area LEDs that exhibit uniform brightness over the entire surface of an LED chip. The optical power and brightness produced by these big chips can even substitute for arc lamps and halogen lamps, a feat high-intensity LEDs can't match.
PhlatLights are claimed to be reliable, too, with device lifetimes greater than 100,000 hours, even under high-current operating conditions. Consider that an incandescent lamp radiates wasted energy as heat, and you'll appreciate the significance of the 100,000-hour metric. It's not easy to get rid of heat in a high intensity LED without proper sinking and a low thermal-path design. Hot running products are unreliable products.
Green ProjectionLuminus’ cool-running mercury-free PhlatLights are making inroads in green projectors, especially portables that weigh less than four pounds. One of these video products, from LG Electronics, uses these LEDs instead of mercury-arc lamps. LG's
HS-101 Ultra-Portable Projector is power stingy, dissipating 60% less power than forerunners and competitive portables. Moreover, while an arc lamp in a conventional projector might last for about 6000 hours, a PhlatLight LED in this service will go for 100,000 hours or more. That’s a number that will probably exceed the lifetime of the projector's other components.
Projectors aren't the only products that can benefit from this technology. The company’s recently introduced CST-90 series of LEDs can be used for lighting in general. Architectural lighting, retail lighting, and residential lighting are just a few proposed applications. Environmentally friendly CST-90 devices can serve as spotlights, bay lights, wide area lights, and even as streetlights.
3000 Lumens Per ChipThese monolithic devices are bright. They emit nearly 3000 lumens from a single chip, with efficiency specs coming in at more than 100 lumens/W (at 350 mA/mm2). They can be driven with currents ranging from 1 A to 13.5 A. With a thermal resistance from junction-to-heat sink of 0.9ºC/W, these devices also tout the lowest thermal resistance of any LEDs. This lets the chips be driven at high current densities, even while maintaining reasonably low junction temperatures.
PhlatLight LEDs also exhibit good shock, vibration, temperature cycling, and humidity resistance specs, a combination that helps reach median lifetime specs above 60,000 hours. Indeed, Luminus confers 2-year warranties on its CST-90 products.
The latest LEDs from Luminus are its SST-90 white devices. "SST-90s come in SMT form-factors that OEMs are familiar with," points out Dave Sciabica, head of the company’s Lighting Business Group.
The light-emitting surface of an SST-90 diode comprises a single monolithic die that’s only 9 mm2, yet it produces 1000 lumens at 10 W input power. At maximum rated drive current an SST-90 can emit 2250 lumens.
Next-Gen ProjectorsOne of the coolest (figuratively and literally) Luminus products is its PT-121 chipset, designed for next-generation data projectors. Rolled out at this year's Consumer Electronics Show, the PT-121 leverages Texas Instruments' DLP digital light processing technology. PT-121 chipsets, comprised of red, green, and blue LEDs, are slated for use in DLP data projectors with micro-displays ranging from 0.65 inch to 1 inch in size.
Like other PhlatLight LEDs, the PT-121 offers instant start up with no warm-up and cool-down periods like those needed for mercury lamps. The PT-121 covers a color gamut that exceeds NTSC standards and surpasses 60,000 hours of lifetime, eliminating the need for frequent replacement of costly projector light sources.
Luminus claims 100% uniform surface emission in this application, which ensures high collection efficiency and low optical losses. In addition, the monolithic emission area per color permits single-lens collection and simplified optics. The red, green, and blue LED chips produce more than 2000 white lumens, excited in a time-sequential pulsed mode.
Moving this technology into the mainstream, Japan’s Nichia Corporation and Luminus Devices inked a cross-licensing accord that covers intellectual property, the technology, and manufacturing rights. Nichia is presently a volume producer of blue and white LEDs, and it's the world's largest supplier of white LEDs; so, with this agreement, we should see PhlatLights proliferate. Whether operation on dc in home and industrial lighting applications will loom as a problem is anyone’s guess.
How many engineers does it take to change a PhlatLight? Let me know. Write me at
amm at en-genius dot net, or post your comments on our blog.
