Monday, February 4, 2013

SpectraVue for Outdoor Signage

When LCDs had terrible viewing angle, many solutions were being developed to fix the issue prescriptively. Of course, the best solution is most always fixing the issue rather than applying a bandaid which is why most of these external fixes were dropped. One of these external fixes was a product called SpectraVue. It consisted of two components, and channel waveguide and a viewing film. The viewing film was an array of cones embedded in a black matrix. Light from the LCD entered the array columnated, bounced off the side of the cones a few times and left the viewing film very dispersed. The film produced an LCD appearance that was virtually the same as a CRT. It was described by Toshiba Labs as "Virtually Perfect viewing angle". Although I have seen several startups and other corporate projects where the intended function of the device depended on building a light funnel, basic geometry shows that funnel structures have exactly the opposite effect on bosons as they do on physical matter. Spectravue takes advantage of this effect to essentially provide something of a photon diode.

Although it was a great solution to the LCD viewing angle problem, it had two problems of its own. The first is that the maker, AlliedSignal, had problems actually manufacturing the product. The second, and more compelling issue was that it was a cost adder. It was being developed at the same time as IPS technology which fixed the problem in the LCD with no additional layers or costs.

Examining the diagram, there is another advantage that SpectraVue had, though it did not count for much at the time. The surface is virtually all blackfill. It adds inherently better sunlight viewability withoug significant loss of display aperture. As IPS development was the reconsideration of an old solution, as I note in my previous post, reconsidering the LCD optical stack might be in order for the digital signage market.

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