Scientists at Sharp's European research headquarters at Oxford Science Park have invented a power-saving device aimed at reducing the battery drain on mobile telephones.

The next generation of mobiles will be able to deliver text, pictures and video.

Sharp's power-saving screen checks the format of each frame as it is displayed. If the information is plain text, the screen switches to low-power mode to display black-and-white, but for video clips it goes into high-power full-colour mode.

Sharp researcher Graham Cairns says the interface also optimises the power needed if different formats are displayed together.