US Patent 7764276 Touch control system and apparatus with multiple acoustic coupled substrates

An apparatus and system for recognizing touch positions is comprised of multiple acoustically coupled substrates, said coupling functioning also as an environmental seal. At least one secondary substrate, with means to transmit and receive acoustic waves, is coupled to a primary substrate capable of propagating acoustic waves such that an intentional touch on the surface causes a perturbation of the waves passing through a desired region of touch detection. Said perturbation is analyzed by circuitry to determine corresponding physical position of the touch on surface.