Patent ID: 8400403

Claim:
A key input apparatus for a portable apparatus, comprising: a display unit configured to display a key selected by a user input; a light sensor comprising: a plurality of light emitting elements disposed at predetermined intervals on a border of a first side of the display unit, and a plurality of light receiving elements disposed on a border of a second side of the display unit to face the light emitting elements, wherein the light emitting elements are configured to generate first light signals at a predetermined angle from a direction in which the light emitting elements face the light receiving elements and wherein the light sensor is configured to output light signal information of at least one of the light emitting elements and the light receiving elements; and an input detection unit configured to: receive the light signal information from the light sensor, detect at least one of the light receiving elements that receive the first light signals using the light signal information, and detect a user's space input position using the at least one of the light receiving elements that receive the first light signals if the at least one of the light receiving elements that receive the first light signals are detected.