Touch-Based Human-Machine Interaction

Abstract

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Piezoelectric Based Touch Sensing for Interactive Displays—A Short Review

“…Furthermore, the different orientations of the same applied force will also result in different responsivities, as the force closer to the perpendicular orientation will obtain more stress in the z-direction. In the study of [ 42 ], it was shown that the responsivity increases by 51% when the touch orientation increases from 30° to 90° as shown in Figure 7 .…”

“…According to the transmission speed and the timing of the mechanical waves, the touch location can be evaluated. However, it only provides 2-dimension information [ 42 ].…”

“…The block diagram of piezoelectric touch panel system is shown in Figure 6 . As the frequency of the piezoelectric signal is 0–10 kHz [ 42 ] while the frequency of the capacitive signal is around 100 kHz, they can be separated smoothly by using a low pass filter and a bandpass filter. The ADC is then used to convert the analog signal to a digital signal, which is then calculated to interpret the force amplitude and the touch location by the signal processor.…”

“… Four typical stack-ups of the piezoelectric touch panel: ( a – d ), the electrodes are on and underneath the piezoelectric film layer [ 42 ]. …”

“…The former is detected by the capacitive layers whereas the latter can be interpreted by the piezoelectric layers. To obtain 3-dimension information, including the x-y position and the force amplitude, the most widely used architecture is the sandwich architecture [42]. In this architecture, two electrodes are attached to both sides of the piezoelectric material.…”