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Advanced Imaging Magazine

Updated: January 12th, 2011 09:49 AM CDT

A Touch of Glass

Touchscreen technology evolving from single touch to multitouch and gesturing
Ocular Inc.
Figure 1. Resistive touch screens have an outer layer of flexible film that must bend to make electrical contact. Projected capacitive touch screens feature a protective glass layer which conducts changes in the screen’s capacitance resulting from a touch.
Digital Dash
Figure 2. Digital Dash’s multifunctional solution uses familiar physical controls like knobs, buttons and sliders, with touch input, while remaining totally reconfigurable in software.
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By Barry Hochfelder

Resistive touch technology called for a layer of flexible film over the visual screen, Mozdzyn explains. “The single touch functions were present in resistive touch applications; however, there are significant durability limitations with the use of film. The next generation of touch panels, the multi-touch, projected capacitive panel, uses a glass faceplate which has multiple benefits, such as advanced gesturing, in addition to being scratch resistant.”

The glass faceplates, he adds, give a more high-tech look and don’t allow for harsh chemicals to damage the surface or get inside the unit and cause additional problems. The all-glass surface also enhances the optical clarity, increases readability and can be used in environments with extreme temperatures. Previous touchscreens could not handle high heat or extremely low temperatures for outdoor applications.

The Iphone, for example, uses projected capacitance, which obviously changed the entire market, allowing improved performance by optical bonding of touch glass to the LCD. With resistive, it’s more difficult to create a smooth, flat surface than it is with capacitive. The cover glass becomes an active element of the screen, so it has to be bonded without an air space between layers.

“Capacitive touch sensing has been around for many years before the iPhone, and if you look at the touchpad on a laptop, it’s really the same thing as a projected capacitive touch panel,” Mozdzyn explains. “The fundamental technology is the same; you just can’t see through them.

“We’ve been in the commercial and industrial side,” he adds. “We’re seeing adoption in all kinds of products—appliances, autos, thermostats. You name it. Everybody is looking at using touchscreens larger than handhelds and mobile devices.



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