Key input method and apparatus for portable apparatus

摘要

A key input apparatus for a portable apparatus includes a display unit that displays a key selected by a user input. The apparatus includes a light sensor comprising a plurality of light emitting elements and a plurality of light receiving elements. The respective light emitting elements generate first light signals upward at a predetermined angle from a direction in which the light emitting elements face the light receiving elements. The apparatus also includes input detection unit that detects the light receiving elements that receive the first light signals, and detects a user's space input position using the light receiving elements that receive the first light signals if the light receiving elements that receive the first light signals are detected.