Backlights

Backlights

Posted Nov 25, 2008 15:30 UTC (Tue) by sladen (subscriber, #27402)
In reply to: Observations on power management by sbergman27
Parent article: Observations on power management

The digital watch you're describing is using a simple LCD display (not a VFD/TFT/LED). If you were to flip the polarising glass over on the watch (more easily done on a household/school calculator) then you will have a display that default to black, with clear (reflected) writing.

In a self-illuminated colour TFT display, the bright white backlight is used as a starting point, and selectively blocked out (meaning "black" never looks quite black). Transreflective screens complement the blacklight with reflected incoming light (as with the digital watch/calculator's primary source).

Finally, high-end recent flat-screen displays are now are able to selectively shut-off/tone down the output of the backlight in areas where the image is dark or black; by avoiding producing extra light in the first place, less of that light needs blocking to produce a satisfying black.

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