Conventionally yes, this is true. However, what actually happens is that when power is applied, the liquid crystals twist the polarity of the light (from an initially polarized bottom polarizer) such that the light and the top polarized layer have a different polarity and light is blocked from being transmitted through. It should be feasible to allow the transmission of light when power is applied by simply changing the configuration of the top polarizer (yawing it 90deg relative to the polarizer beneath the LCD)! A great vid: http://www.youtube.com/watch?v=jiejNAUwcQ8 Even a MEMS or 'e-ink' esque solution should be possible requiring power only on a shift. Again, it's a play on polarity of light with multiple layers. My only concern would be a loss of visibility if there was a crack in the glass!