Many of the publicity photos for pico-projectors show happy teenagers showing bright, clear images in a well-lit room (or outside!) using another teenagers back as a projection screen. How realistic is this scenario, considering the integrated pico-projectors they are using are expected to generate perhaps 7 lumens when they become available in 2009?

Matt Brennesholtz
Insight Media Analyst

Regardless of the contrast or color gamut of the projector itself, in a high ambient light environment all projected images look badly washed out with desaturated colors. This occurs in a well-lit area, especially with a low gain screen such as a shirt or a flat white wall. The brighter the projector, the less serious the effect, which is one of the main drives behind 1000 and 2000 lumen conference room projectors: to make the image look good even when there is enough light for people at the meeting to take notes.

With 5 - 15 lumen integrated pico-projectors in 2009, 10 - 25 lumen companion pico-projectors in 2008 or 25 - 100 lumen pocket projectors available now, this brute force approach to making acceptable images in the presence of ambient light doesn’t work, unless you want the same sized image you can have for free on your cell phone. Ambient light rejecting screens are the best answer to this problem.

Brightview Technologies is one company that makes a variety of ambient light rejecting screen materials and they sent Insight Media a sample. The sample screen was their Gigascreen super high gain material with a horizontal viewing ½ angle of 20°, a vertical ½ angle of about 10° and a gain of about 7.8. It was mounted side-by-side with a piece from a white vinyl gain 1 screen. We tested it using our low-brightness Torpedo game projector (DD 11/7/07).

The difference in image quality between the Gigascreen and the gain 1 material was like night and day-as long as you stayed within the viewing angle cone. Contrast was higher, the image was brighter and the colors were much more saturated. Later when we talked to Don Hirsh and Rob Woods at Brightview, we asked about the color improvement. They said there was no deliberate wavelength selectivity in the screen, although there was a slight wavelength dependence in the 100µm microstructures that made up the screen. The color improvement we saw occurred because ambient light washes out colors, making them more desaturated.

Brightview has designed a portable screen using this material, as shown in the photos. The screen rolls up into a self-contained case for portability and sets up in seconds. There is a video demonstration on the Brightview website (www.brightviewtechnologies.com). There is also a white paper on the site stating the advantages of high-gain screens in rejecting ambient light. While Hirsh says they don’t have any formal life test data on the screen material, they have a prototype they have been using for six months without signs of wear. The material is very abrasion resistant and can be cleaned with Windex or soap and water and a rag or paper towels.

While kids might not want to carry a projection screen in their backpack, I can easily see a businessman with a pocket projector carrying one in his briefcase. If you are planning on using your pocket projector in areas with uncontrolled lighting, a screen like this may become a "must have" item.

Read more about pico-projectors in the Insight Media pico-projector market segment analysis (http://insightmedia.info/reports/2007picoprojdetails.php). This report is available now, and all purchasers will get the update we are planning to finish after CES in January.

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