A British company called Peratech has announced a new technology for touch screens that registers pressure as well as the position of a finger. This could provide new ways of interacting with apps for touch screen mobile phones and tablets.
In addition to adding pressure sensitivity to screens, the company claims that the technology, called Quantum Tunneling Composite (QTC) Clear, could make touch screens thinner, more rugged, and more energy-efficient.
Peratech aims to bridge the gap between the two main touch-screen technologies: capacitive and resistive, says joint CEO Philip Taysom. Capacitive touch screens are found in mobile phones and tablets. They respond quickly to multiple fingers at a time, but rely on a grid of electrodes that constantly draw power when a screen is switched on; the bigger the screen, the more power the capacitive sensors gobble up.
Resistive touch screens were used in some early generation handheld devices, and are commonly found at ATMs and point-of-sale screens. They use less power, which makes them more appealing for larger displays, but they aren’t as responsive or as durable as capacitive touch screens.
Resistive screens are built by sandwiching a thin layer of air between two sheets of relatively soft material. Applying pressure on the screen forces the layers into contact, closing a circuit and registering a touch. It’s a simple approach, but it doesn’t allow for high precision or multitouch. And because the screens are constantly deformed, longevity is an issue.
Taysom claims that QTC Clear has the benefits of both technologies while avoiding the downsides of either. A layer of composite material, composed of electrically conducting particles, is sandwiched between sheets of a rigid material like glass. When a finger or stylus presses the top sheet of glass, the particles in the composite conduct electricity proportional to the pressure applied. And, unlike capacitive screens, the system only draws power when touched.
A QTC Clear screen could be more durable than resistive touch screens. Instead of requiring an air gap of a fraction of a millimeter, as with resistive screens, the company uses a six-micron layer of composite material. “There’s a lot less of a gap,” says Taysom, “and that has a number of significant benefits.”
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