The LEDs also simplify a projector's design because they create individual red, blue and green beams of light. This eliminates the need for the single hardest part of a standard projector to design and build properly -- the spinning color wheel that separates the bulb's white light into its primary colors before reflecting it off of the imaging chip.
Instead of light running through a tiny LCD panel, think mirrors, lots of them. The Optoma Pico PK-101 and the Dell M109S use a Digital Light Processing (DLP) chip from Texas Instruments. The chip's surface has hundreds of thousands of microscopic mirrors that swing into and out of the beam of light to selectively reflect a pattern. Each micro-mirror corresponds to an individual pixel onscreen.
By contrast, 3M's MPro110 uses Liquid Crystal on Silicon (LCOS) technology, which has no moving parts. Rather than tiny mirrors moving back and forth, LCOS uses a special reflective LCD panel where the pixels either reflect or absorb the LED's light. It's like a magical mirror that can control what's reflected off its surface.
Limitations
The downside is that these devices run the risk of looking more like flashlights than projectors. While conventional projectors put out between 2,000 and 3,000 lumens of illumination -- about what a car headlight produces -- the best pocket projectors produce less than 100 lumens.
They require darkened rooms and will fail to satisfy for a big meeting with dozens of participants. On the other hand, they should be fine for presenting to a small group and are perfect for impromptu gatherings. "It's just enough light now," says Insight Media's Brennesholtz, "but I expect that the technology will evolve and brightness will increase rapidly."
What these pocket projectors lack is as important as what they have, and many presenters will be disappointed by their minimalist designs. None of the three has a lens cover, a remote control or adjustable feet for aiming the projector's beam. Plus, only the Dell M109S has keystone correction to square the image when it's projected at an angle.
Still, their miniscule size and weight make them very attractive in certain circumstances. Read on to see how they performed in my tests.