A touch sensor comprising an
acoustic wave transmissive medium having a surface; a plurality of
acoustic wave path forming systems, each generating a set of incrementally varying paths through said transmissive medium; and a
receiver, receiving signals representing said sets of
waves, a portion of each set overlapping temporally or physically by propagating in said transmissive medium along axes which are not orthogonal. The
waves may also be of differing wave
modes. The
receiver system may include a phase, waveform or amplitude sensitive
system. Reflective arrays are associated with said medium situated along a path, said path not being a linear segment parallel to a coordinate axis of a substrate in a Cartesian space, a segment parallel to an axial axis or perpendicular to a radial axis of a substrate in a cylindrical space, nor parallel and adjacent to a side of a rectangular region of a small
solid angle section of a sphere; situated along a path substantially not corresponding to a desired coordinate axis of a touch position output
signal; situated along a path substantially non-parallel to an edge of said medium; has a spacing of elements in said array which differs, over at least one portion thereof, from an integral multiple of a
wavelength of an incident
acoustic wave; has elements in said array which are non-parallel; has an angle of acceptance of acoustic
waves which varies over regions of said array; and / or coherently scatter at least two distinguishable acoustic waves which are received by said receiving
system.