US Patent 10175771 Secured compact keyboard

A keyboard of a data entry device includes a printed circuit board, a spacer having a plurality of key-positioning locations, a plurality of keys, each key being disposed so as to be at least indirectly in contact with a corresponding key imprint on the printed circuit board and a plate of transparent material in which holes corresponding to each key are made. The printed circuit board, the spacer and the plate of transparent material are applied so as to constitute an assembly that is non-dismountable from the exterior of the data entry device.