Earlier this year, we profiled LED-based rear projection TVs using Luminus Devices’ PhlatLight technology. Several readers also expressed interest in LED-based front projectors. Well, after returning from the 2008 CEDIA show, I can definitely say that LED-based front projectors will be coming to a home theater near you in the not-so-distant future.
At this time, LED illumination seems to be focused solely on those projectors utilizing Texas Instruments’s DLP imaging technology. But Epson, who created the competing 3LCD display technology, believes that LED illumination will also be used in their projectors sometime in the future (but would not specify if it was next year or a couple of years from now).
Arc Lamps and Color Wheels
Currently, front projectors that use DLP technology require an arc lamp, color wheel, and mechanical shutter to produce images. Lamps offer terrific brightness, but burn out after a couple of thousand hours or so, and need to be replaced. Replacement bulbs can run several hundred dollars. LEDs, on the other hand, offer a stable light output solution during the entire life of the projector. Whereas, arc lamps decrease in brightness over time because of fading (and become dimmer), LEDs offer a constant and consistent light source over time. And, unlike arc lamps, there is no mercury in LEDs so there’s no replacement hazard or stockpiling of hazardous materials in landfills. LEDs are also an energy-efficient and green technology.
Color wheels have always been problematic in my mind. They spin at high RPMs, but can be subject to noise and mechanical degradation over time. Color wheels may also contribute to the annoying (for some people) “rainbow” effect that has plagued DLP projection displays for years. In my life as a product reviewer, I’ve even had sets with color wheels that wobbled distorting the on-screen image. Employing a stable light source such as LED (rated at somewhere between 50,000 and 100,000 hours of viewing) to illuminate front projectors eliminates another potential defect by taking away the color wheel entirely. Lastly, LED illumination also takes away the mechanical shutter, which has its own set of problems. Overall, the LED illumination system replaces the lamp, the color wheel and the shutter of a traditional projector. What is crucial here is that various companies have come together to produce a precise and complex control algorithm that allows the LED to work with the DMD to get high image quality.
The benefits of LED illumination are many fold including: Deep saturated colors (160-percent of color gamut as compared to NTSC), Precise brightness control (8-bit brightness for red, green & blue that improves contrast ratio, color resolution and grayscale), Fast and precise on/off switching (less than 1 millisecond), High stability of light output (for deeper blacks without mechanical iris), Long lifetime (between 50,000 – 100,000 hours), and Energy efficient (reduced power consumption). In fact, LED lighting is also moving throughout the home and your automobile.
Projectors powered by PhlatLight produce a reported 40-percent more color than traditional lamp-based displays due to the technology’s ability to individually create pure, primary colors. Luminus has been manufacturing its patented PhlatLight LEDs for DLP TVs since 2006 and claims PhlatLight LEDs remain the only LEDs that are bright and efficient enough to replace arc lamps in front projectors. They are much larger than conventional LEDs and are designed to operate reliably at significantly higher intensity.
According to Luminus, PhlatLight LEDs are environmentally friendly, and free of hazardous materials such as mercury or lead. Reportedly, these projectors consume approximately one-third the power of comparable lamp-based projectors and produce an instant-on image at full brightness without the cost and inconvenience of lamp replacement.
Delta Electronics announced at IFA and CEDIA that it has completed the development of a Full HD LED projector for the consumer market. Delta estimates the life of their LED module at more than 20,000 hours of normal operation. With its experience and close partnership with Texas Instruments, Luminus Devices and other key suppliers, Delta believes it has an early advantage in recognizing the feasibility of PhlatLight LED and the value of LED projectors, and hopes to commercialize this product in the near future.
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Dennis has been involved with Consumer Electronics forever it seems. His 25+-year career includes a 12-year tour of duty at Consumer Reports magazine, as well as stints as a product reviewer, market analyst, technical editor, and consultant for the electronics industry. He lives in Ossining, NY with his two children, one demanding cat and piles of A/V equipment.