Touch panel for an acoustic touch position sensor using shear wave propagation

Abstract

Abstract An acoustic touch position sensor is shown in which a transducer coupled to a side of a substrate imparts a shear wave into the substrate for propagation along a first axis. A reflective array is disposed along the first axis to reflect portions of the shear wave along a plurality of parallel paths extending across a touch surface of the substrate to a second reflective array the axis of which is parallel to the axis of the first reflective array. The second reflective array reflects the shear waves incident thereto to a transducer mounted on the side of the substrate and responsive to shear waves propagated thereto for providing a signal representative of these shear waves. A touch on the substrate results in a partial absorption of the energy in the shear wave so as to produce a perturbation therein which is sensed to determine the axial position of the touch on the substrate. In another embodiment of the present invention a laminated touch panel is provided such that a back plate of any desired thickness is bonded onto the touch substrate. A nonshear wave coupling adhesive may be used to bond the back plate to the substrate. Alternatively, the back plate may be chosen such that the velocity at which acoustic waves propagate in the back plate is greater than the velocity at which acoustic waves propagate in the substrate. The touch panels of any of the embodiments shown may include means for suppressing spurious acoustic waves.

Inventors

• 👤 Terence J. Knowles

Bibliographic Details