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See through force sensing material for touchscreens

Posted: 07 Apr 2011 ?? ?Print Version ?Bookmark and Share

Keywords:force sensing? touchscreen? QTC Clear?

Peratech has developed a see through version of their Quantum Tunnelling Composite (QTC) material called QTC Clear. This force sensing material can be used to create a whole new class of Force Sensitive touchscreens that, Peratech claims, can replace current resistive touch screen technologies or enhance capacitive ones to create solutions with more features such as 3D input.

The QTC Clear layer is 6-8 microns thick with a transparency similar to existing touchscreen technologies. This is sandwiched between two layers of Indium Tin Oxide (ITO), which is in turn sandwiched between two hard sheets, typically glass. It is so sensitive that it can detect deflections of only a few microns so that the top surface can be rigid and robust, e.g. glass, unlike current Resistive designs that have to be soft enough to deform easily making them susceptible to damage. QTC boasts that virtually no current flows unless a force is applied. This overcomes the drawbacks of capacitive designs that constantly draw current and create design challenges to overcome EMI issues.

Resistive touchscreen manufacturers can upgrade to QTC Clear and use their existing manufacturing procedures and equipment to produce this new class of Force Sensitive touch screens. Capacitive touchscreen manufacturers can augment with the addition of QTC Clear to provide additional features from the force sensitivity such as touch activation of the capacitive matrix to save power, 3D menus, variable line widths, and more intuitive gaming interaction. The company says very little alteration is needed to the control electronics in either case except to take advantage of the new features.

QTC Clear

Peratech's QTC Clear can detect minor deflections.

QTC Clear is available under license from Peratech and has already been licensed to a leading touch screen manufacturer. Licensing terms are competitively positioned so that manufacturing costs are only slightly greater to reflect the additional commercial benefits that using QTC Clear brings.

About QTC
QTC's are electro-active polymeric materials made from metallic or non-metallic filler particles combined in an elastomeric binder. These enable the action of 'touch' to be translated into an electrical reaction, enabling a vast array of devices to incorporate very thin and highly robust 'sensing' of touch and pressure. QTC's unique properties enable it to be made into force sensitive switches of any shape or size. QTC switches and switch matrices can be screen printed allowing for development and integration of switches that are as thin as 75 microns.

QTC is low power and interfaces can be designed with no start resistance so that without pressure, the switch draws no power and passes no current. Importantly, when pressure is applied, the resistance drops in proportion to the amount of pressure which allows sophisticated human machine interface designs that react to variations in pressure. QTC technology has no moving parts and requires no air gap between contacts. This makes it extremely reliable and suitable for integration into the thinnest electronic designs and with industry leading operational life.

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