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Electronics

Transflective Displays

Electronics - November 2001
Electronics November 2001
By Ben Ellison


Transflective Displays
New sunlight-viewable technology adds to the possibilities--and the confusion.
   
 



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Consider the riches that will accrue to he who can produce a vibrant color LCD screen, viewable in all conditions, and more reliable, less power-hungry, and cheaper than its predecessor. Engineers are hard at it, and we boaters who think we understand sunlight-viewable displays, NITS and all, should not be surprised at yet newer technologies.

Simrad has introduced a line of multifunction marine electronics whose "transflective" displays employ a new blend of LCD techniques. Most marine electronic LCDs are "transmissive," meaning their image quality is dependent on artificial light coming from the back of the display toward the observer. Hence, "sunlight-viewable" displays overcome the brightness of direct sunshine by cranking up the backlighting (measured in NITS). Meanwhile, the latest crop of color handheld devices--like the Compaq iPaq--are "reflective"; a rear polarizer reflects ambient light that has entered the front of the display back through the LCD cells. They are startlingly counterintuitive, getting brighter and more readable the more direct light shines on them; however, the side lighting they use for shaded and dark conditions can be problematic, especially on larger screens.

The Simrad C42 display is something like a one-way mirror, illuminated with reflected available light, artificial backlighting, or both. The results I experienced when I tested one were downright amazing. With a full-on Maine summer sun directly over my shoulder, the Simrad screen was bright and crisp, even with the backlight off. Leaving the backlight on had no effect on the sunlight viewability, but kept the display even and readable in all other conditions. Indeed, the display brightness seemed nearly self-regulating, requiring adjustment--dimming--only as night truly fell.

There are many implications of transflective technology. While the displays seem to cost about as much as the current crop of high-NIT units, the technology looks much less complex so it may become less expensive. The elimination of high-bright backlighting also means less electronics-damaging heat, which makes it easier to build the displays thin and waterproof. Simrad is first with large transflective marine displays, which it calls "SunView," but is also quick to note that the basic display parts are made by Sharp and are available to any marine manufacturer. In fact, John Caballero, Simrad's U.S. general manager, predicts that "in 18 months high-NIT monitors will be replaced by transflective units throughout the industry."

The low power needs of transflective displays should also mean that good handheld color displays are possible, but my initial experience with one was ambiguous. I refer to the new Garmin GPSmap 176C. It's a WAAS-enabled handheld able to display Garmin's new "Blue Chart" full-detail vector marine cartography on its 3.8-inch-diagonal screen. The charts are excellent, and the unit is fast and full of well-designed software goodies like tide and celestial predictions and searchable databases of nav aids, anchorages, even restrooms! The 176C was quite readable in full sun or in darkness but washed out notably in overcast or under-the-bimini conditions; the backlighting simply didn't contend well with indirect daylight. I suspect that Garmin's alternate monochrome display has a greater range of readability, but then again it wouldn't show the chart detail as well without color.

Next page > Transflective Displays continued > Page 1, 2

This article originally appeared in the June 2003 issue of Power & Motoryacht magazine.

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