For most of us, touch interactivity is how we interface with our phones and tablets, as well as a growing number of smart home appliances and even the cars we drive. Given the mainstream adoption of touch control available on consumer devices, it's no surprise that a feature like force (or pressure) sensitivity is increasingly common on larger touchscreens used in kiosks, touch tables and interactive video walls.
Applying force sensing techniques used in handheld devices to large touchscreens used in commercial applications such as kiosks is not a matter of simply scaling up the same technology. Most smartphones with a pressure sensing capability use thin projected capacitive touch sensors applied to a "piezoelectric" layer mounted atop the display. Scaling this approach to a large screen would be very costly, and is also incompatible with the thick, rigid, impact-resistant glass often used in kiosks and other touchscreens found in public places.
So the race is on to deliver force sending capabilities to these larger format displays.
One sensible approach is based on measurement of the surface area of an applied touch, which alters 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. And because this functionality is enabled via the touch controller's firmware, existing customers could retrofit force sensing by updating the firmware and adapting their application software to respond appropriately.
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 smartphones today. For example, in wayfinding or web browsing applications, a soft touch could open a preview window — then by pressing harder, fully open the window.
In the case of a kiosk, a soft touch could bring up a menu of options, while increasing the applied force could complete the selection. This opens up new opportunities for making kiosks more accessible to partially sighted users, and potentially eliminates 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 that activates the choice.
Developers could also create drawing and writing applications that respond to applied force without an active stylus. I expect the kiosk industry in particular will be quick to adopt force sensing in future models, with users responding positively to this new interactive capability.
Ian Crosby is Zytronic's VP of Sales & Marketing, managing the companys growing global commercial activities. Prior to Zytronic, he was Global Account Director at Filtrona, and before that he spent 15 years at Corning Incorporated. Ian earned a BSc (Hons) in combined Science at North Staffordshire Polytechnic in 1988.www