1. An electronic device, comprising: a touch screen, comprising: a sensing array comprising a plurality of sensors of the same type, wherein a first number and a second number of the sensors are activated when the sensing array is respectively in a fingerprint sensing mode and a touch detection mode, and the first number is larger than the second number; and a display panel, comprising a displaying area, wherein a sensing area of the sensing array is smaller than or equal to the displaying area; a processor, for determining whether a user's finger touches an icon displayed on the display panel when the sensing array is in the touch detection mode, wherein the icon corresponds to an application, wherein when the processor determines that the user's finger touches the icon displayed on the display panel, the electronic device controls a first sensing area of the sensing array corresponding to a first displaying area of the icon to enter the fingerprint sensing mode to capture a fingerprint image of the user's finger for fingerprint recognition, wherein when the processor determines that fingerprint recognition is approved, the processor activates the application corresponding to the icon.