Patent ID: 8330728

Claim:
An information input device for a portable electronic apparatus comprising a touch unit for perceiving a touch from a user and generating a change in current, a current detection unit for detecting said change in current and sending corresponding detection signal, an input information generating unit for generating input information based on said detection signal and an output interface for transferring said input information to said electronic apparatus, wherein said information input device further comprises: an input state acquisition unit for acquiring and judging whether the input state is a trackpad input state or not when the user uses said portable electronic apparatus; and an input switch unit for turning on the trackpad-type input of said portable electronic apparatus when the said input state is a trackpad input state, otherwise turning off the said trackpad-type input; wherein said touch unit includes a plurality of sensors each configured to sense the touch from a user and generate a change in current, and said current detection unit detects change in current of each sensors, said input state acquisition unit comprises an area-calculating module configured to calculate, as a sum number of the sensors having a change in current, a size of a contact area between the user and the touch unit based on said detection signal from the current detection unit.