Rear-Projection Tiled Digital Media Walls

Modular video building blocks provide high-impact solutions for interior spaces
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Sponsored by Christie® for Christie MicroTiles®
Barbara A. Nadel, FAIA

Digital Technology Formats

To understand the benefits of rear-projection tiled digital media walls, it is helpful to review the basics of various digital technology formats. There are three commonly used technologies: light-emitting diode (LED) screens, flat panels and traditional rear projection.

The outdoor advertising industry often uses LED screen displays on large billboards along highways or in major city centers such as New York’s Times Square or London’s Piccadilly Circus. Two specific characteristics of LED displays present serious obstacles to indoor use.

First, the brightness of most LED displays ranges from 2,000-6,000 nits, which is well suited for outdoor applications in direct sunlight, but too bright for most indoor environments.

Second, LED displays are made up of thousands of small light-emitting diodes that combine to produce visuals that appear crisp from a distance. However, the closer viewers get, the worse the images look because of what’s called the pixel pitch. The pixels on an LED display wall are spaced much further apart than with flat screens or rear projection, making them better suited for longer viewing distances. Even with the most densely populated LED screens, where LED clusters are spaced 3 mm apart on centers, viewers should be standing at least 30 feet away. Closer spacing generally produces a sharper image as there are more pixels in a given area. A pixel pitch of less than 0.6 mm provides super-fine quality images even when viewing from up close.

Liquid crystal display (LCD) and plasma flat panels found in public and commercial spaces are very similar to the consumer models found at home, except typically they have been optimized for longer operation and offer a greater range of inputs and integrated features. Nevertheless, even commercial flat panels are prone to image retention over time, and lack the richly saturated colors of LED-based rear projection.

Within the last few years, flat panels with relatively small bezels have entered the market. These can be tiled together to form a single canvas with image-to-image gaps between each panel of 2 to 6 mm. Although the size of these seams is ground breaking for flat panels, they remain large enough to disrupt the image at typical viewing distances.

Traditional rear projection is another option for digital media displays in large spaces, but challenges also exist. These systems may require special optical film on glass to eliminate shadows or silhouettes. In addition, the physical requirements of traditional rear-projection displays frequently demand unimpeded access to the rear of the projection media for servicing. Those arrangements are often difficult to achieve in existing spaces, unless the displays are mounted above and out of the way, and therefore out of natural sightlines.

Many rear-projection systems use lamps to generate their bright images. These lamps are rated to last for months, not years, before needing replacement. The cost of the lamp bulbs, and the labor associated with changing them, has typically ruled out projection systems as viable options for most digital signage projects.

However, a new approach to tiled rear-projection systems has overcome these challenges. Through the use of digital light processing® (DLP®) technology, LEDs instead of lamps and a small tile form factor, issues associated with digital displays in interior areas—such as physical space, maintenance and cost—are resolved. These rear-projection tiles are video building blocks that can be organized in almost any size or shape, without thick, unsightly seams between units, or compromises on contrast and clarity found in other formats. These display modules have super-fine pixels that are viewable from any distance, with superior viewing angles.

An asymmetrical hexagon with a passageway in the middle fuses mission, message and architecture at Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada.

 

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Originally published in Architectural Record
Originally published in September 2012

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