TOUCH SCREEN

A touch display screen includes a display panel, a touch-sensing part, a biosensor and a controller. The touch-sensing part is disposed on a light emitting side of the display panel and has a touch-sensing surface. The touch-sensing part includes a light-emitting device and a light receiver. The light-emitting device is used to provide at least one positioning light and at least one high-energy light. The light receiver is used to detect a change of the positioning light on the touch-sensing surface in response to a touch action and determine the position on which the touch action occurs on the touch-sensing surface. The biosensor is used to determine whether a living body getting close to the touch-sensing surface. The controller is used to drive the light-emitting device to selectively provide the positioning light and/or the high-energy light to the touch-sensing surface according to the determinations of the biosensor.