Extending battery life

HP researchers have come up a new way to reduce the amount of power used by the displays of mobile devices such as PDAs.

“Right now, there are only two things you can do to reduce the amount of power used by the display – you can dim the entire screen or have a smaller display. We thought there should be something better,” says Partha Ranganathan, a researcher at HP Labs.

So Ranganathan and his colleagues Ken Nicholas, Erik Geelhoed and Meera Manahan developed software that monitored the PDA’s screen when it was in use and automatically dimmed ‘ unimportant’ pixels. The team then tested the solution on a group of volunteers.

The result: Display battery life lasted from two to 11 times longer, depending on what the user was doing. What’s more, 95% of users said they preferred the new interface, even without the energy-saving advantages.

The team also explored changing the default appearance of the screen. The default display for an MP3 player has two hours of battery life. But one altered to highlight only the most frequently used features – the “Play” button, the names of the tracks and the equalizer – was able to last three times longer.

An alternate MP3 design targeted at those use the display infrequently (because they’re listening to music, for example) provided a twenty-fold improvement in battery life.

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