Z-axis sensing unlocks new touch potentials

Ian Crosby
Sales and Marketing Director
capture force sensing
Ian Crosby looks at some new innovative developments for transitioning touch screen technology from smaller devices used on smartphones up to much larger devices.

Smart phones and tablets are still the benchmark for touch experience for most users, so it’s no surprise that no sooner has a feature like force or pressure sensitivity become available on consumer devices, then it is also released on larger touch screens used in kiosks, touch tables and interactive video walls.

Extending force sensing from handheld devices to large touch screens used in commercial applications is much more than a matter of simply scaling up the same technology. Most smart phones with Z-axis sensing capability use thin projected capacitive (p-cap) touch sensors applied to a piezoelectric layer and mounted over the display.

This approach would be very costly if scaled up to a large screen, and is also incompatible with the rigid, thick impact resistant glass often fitted to kiosks and other touch screens used in public places. Zytronic’s approach is based on a measurement of the surface area of an applied touch, which changes the measured capacitive signal levels at the relative touch location on the sensor. This enables the measurement of applied force or pressure, even on vandal resistant toughened glass surfaces.

The feature is also entirely implemented in the touch controller firmware, so existing customers could retrofit force sensing by refreshing the firmware and adapting their application software to respond appropriately.

Z-axis, force or pressure sensing literally and figuratively adds a new dimension to the touch experience. It is particularly powerful when used in combination with multi touch technology, exceeding what is possible on all but the most advanced tablets and smart phones today. For example, in a wayfinder or web browsing application, a soft touch can open a preview window – then by pressing harder, fully opens the window. On a kiosk, a soft touch can bring up a menu of options and increasing the applied force makes a selection.

This opens up  new opportunities for making kiosks and ATMs more accessible to partially sighted users, and potentially takes away the need for a user to be constantly looking at the touchscreen during use (as they can receive feedback without committing to a selection on the screen) - with an initial touch triggering an audio confirmation of the selection, then increasing the force activates the choice. Developers can also create drawing and writing applications that respond to applied force without an active stylus. There is huge potential for innovative music applications, as well as for gaming and other smart user interfaces.

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