Designed for long service thanks a high-efficiency, extended-service-life backlight (50,000 hours*)
* Measured at ambient temperature of 25° C, with display on continuously. Service life is considered to have ended when luminance reaches 50% of its initial value. Service life will vary depending on environmental and usage conditions.[link|http://sharp-world.com/corporate/news/001205.html|Sharp link.]
That's well over 5 years of continuous use. I would think an active screensaver (other than blank black screen) would constitute use.