Touchscreen panel haptics

Touchscreen system for generating haptic excitations comprises: a touchscreen panel (91, figure 35) for measuring force and/or capacitance; one or more first and one or more second piezoelectric transducers, e.g. discrete ceramic piezoelectric transducers 86, arranged to generate excitations in the panel; a pressure and/or capacitance sensing module 71 configured to measure force and/or a capacitance from the panel. Haptic driving module 98 drives the first and second transducers at first and second frequencies, the difference of these frequencies being a beat or beating frequency perceptible by human skin, or at a modulated carrier frequency perceptible by human skin. In an aspect the first and second piezoelectric transducers, which may be arranged in linear arrays 95, 96, generate excitations along first and second lines, the second line being inclined to the first line at an angle selected to cause Moire fringes. Each piezoelectric transducer 86 may comprise a first electrode, a second electrode and a layer of piezoelectric material. May be used to generate haptic vibrations in a mobile device, e.g. a smartphone or tablet, in silent mode or to provide tactile user feedback relating to input.