Touch force estimation in an ftir-based projection-type touch-sensing apparatus

A device for data processing in relation to an FTIR-based projection-type touch-sensing apparatus, wherein the touch-sensing apparatus is operable to generate projection signals for radiation that has propagated on plurality of propagation paths by total internal reflections inside a transmissive panel beneath a touch surface on the transmissive panel such that a touching object on the touch surface causes attenuation of at least one of the projection signals, said device comprising a signal processor configured to:

• obtain a time series of magnitude values representing a magnitude of a peak in a time series of two-dimensional interaction patterns generated by image reconstruction processing of the projection signals, the peak corresponding to the touching object on the touch surface;
• and
• generate, as a function of the time series of magnitude values, a time series of force values representing the application force of the touching object onto the touch surface.

A device for data processing in relation to an FTIR-based projection-type touch-sensing apparatus, wherein the touch-sensing apparatus is operable to generate projection signals for radiation that has propagated on plurality of propagation paths by total internal reflections inside a transmissive panel beneath a touch surface on the transmissive panel such that a touching object on the touch surface causes attenuation of at least one of the projection signals, said device comprising:

• means for obtaining a time series of magnitude values representing a magnitude of a peak in a time series of two-dimensional interaction patterns generated by image reconstruction processing of the projection signals, the peak corresponding to the touching object on the touch surface;
• and
• means for generating, as a function of the time series of magnitude values, a time series of force values representing the application force of the touching object onto the touch surface.