Prysm, Maker of Laser Screens, Quietly Breeds a Large-Display Revolution in Concord

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the picture shows up. Other parts of Prysm’s devices are made in Bangalore, India, and the finished displays are assembled at the startup’s headquarters in San Jose, CA.

Tan and his colleagues gave me a comprehensive tour of the lab spaces where Prysm’s 35 Concord-based employees are building and testing the screens. So comprehensive, in fact, that it included many of the “secret sauce” particulars that tech companies are usually loath to reveal to anyone, let alone journalists. In exchange for this rare glimpse behind the scenes, I agreed to gloss over some of the key details in this writeup.

John Ritter, Senior Director of Process Development, PrysmJohn Ritter, senior director of process development at the Concord plant, spends a lot of his time in the clean room. He explained to me that the job of the screenprinting devices—by far the most expensive machines in the building—is to deposit thin stripes of material on the ribbed polymer mats at the heart of the Prysm screens. There are four machines: one for the red phosphor stripes, one for blue, one for green, and one for the glue used to bond each mat to a base layer of glass.

If you look closely at a finished Prysm screen, you can make out the individual red, green, and blue stripes, which are reminiscent of the phosphors on the inside surfaces of the cathode ray tubes in old-fashioned televisions. This is part of what I mean when I call Prysm’s technology “old meets new.” The beauty of Prysm’s laser phosphor technology is that the screens have no fixed pixels. Rather, a tiny dot of color shows up whenever a laser beam strikes one of the phosphor stripes, in much the same way that the phosphor dots in a CRT light up when struck by an electron beam. This way, there’s no need for the complicated, expensive, finicky array of switches and transistors that drives the individual pixels in a flat-panel LCD or LED display (the so-called “backplane”).

Prysm's panel manufacturing lineOf course, if you want to draw a high-definition video image on an LPD screen at 30 frames per second, some fancy engineering is required to direct the laser beams to the right spots. That’s the job of the so-called “light engine” portion of the Maui units. The light engines aren’t manufactured in Concord, but Tan showed me around a testing lab where several of these engines were in various states of dishabille. They resemble compact versions of the tabletop optics experiments your high-school physics teacher probably showed you, with lots of lasers, lenses, and mirrors.

The core of the light engine is an array of indium-gallium-nitride laser diodes, which emit coherent beams of light at the same 405-nanometer wavelength used in Blu-ray players. There have been many previous attempts to build laser-driven displays, but the real “aha” moment that gave Prysm’s founders hope for their own technology, senior director of systems and test engineering Dave Kent told me, was the realization about five years ago that the laser diodes then being developed for optoelectronic storage devices like Blu-ray players would be perfect for display applications. Not only would these lasers be relatively cheap, since there were already plans to mass-produce them for Blu-ray players, but … Next Page »

Wade Roush is a contributing editor at Xconomy. Follow @wroush

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