Optoelectronic keyboard

Claim 1

An optoelectronic keyboard, comprising: a plurality of transmitting elements for transmitting a luminous flux, a plurality of receiving elements for receiving said flux an activation circuit for activation of the individual transmitting elements in one of time or frequency multiplex operation or a special merged operation, an evaluation circuit for processing the signal path of different multiplex cycles received by said receiving elements, said evaluation circuit including predetermined threshold values and means for adding consecutive multiplex cycles to determine signal changes, a main body in which said transmitting and receiving elements are arranged, said main body including a cover and having a first space for flux flow between said elements and a second space for housing said evaluation circuit and said activation circuit, said first space for flux flow in the main body being separated and shielded from the second space containing the activation and evaluation circuits, a plurality of mechanical keys guidably arranged in said cover and having key stems shaped for altering flux flow between said transmitting and receiving elements and for converting diverging bundles of rays from said transmitting elements into essentially parallel bundles of rays which extend essentially parallel to said cover, with the changes in the luminous flux caused by actuation of one of said keys resulting in a signal which defines the actuated key, and shielding for said main body that has the effect of an optical and electromagnetic shield and including shielding means comprising one of a metal coating and a metal plate which encloses the entire space containing the evaluation circuit and which is provided with openings for entering and exiting light.