InGlass™ technology extends the range of touchscreen size and capabilities

November 27, 2015 // By EDN
Charles Limonard, Product Marketing Manager, Dialog Semiconductor
The capacitive touchscreen has revolutionised the design of user interfaces across a wide range of consumer devices, from smartphones to digital signage. The ability of capacitive touchscreens to recognise multiple touches has made it possible to create increasingly intuitive systems and enable new ways of interacting with them. But the capacitive touchscreen technology has limitations. It does not scale readily to larger displays. Capacitive’s ability to detect touch positions degrades as the size of the screen increases beyond a certain limit. This is a problem for new applications that need large displays. This article describes a solution to the problem.

Signs and billboards based on multitouch technology will provide ways for advertisers to interact with potential customers, allowing users to zoom in on products displayed in an end-of-aisle display within a shop or a large panel outdoors. In schools and colleges, teachers and students can move from simple electronic whiteboards to interactive displays that let them find images and text online and then zoom in annotate them for the rest of the class.

A technology that supports large displays of more than 20in can also change the way we think about building industrial and other real-time control-oriented applications. A single display can replace entire banks of readouts and dials – and let operators interact with more intuitive controls. They could touch an object on the screen to see its detailed state and then dial in new parameters with another finger instead of having to type in detailed commands or find a relevant control on a separate panel of controls.

A technology exists that can enable these 15-110” applications: InGlass™ multi-touch, otherwise known as planar scatter technology. As its name suggests, InGlass™ multi-touch technology by FlatFrog uses the way that transparent materials reflect light internally if the light hits them at an angle greater than a critical angle and the refractive index of the medium beyond the surface is lower than that of the transmission material itself. Unlike, capacitive solutions it does not require light obstructing sensors that can degrade the visual transparency, resulting is an uncompromised visual experience.

If an object touches the surface, the internal reflections are frustrated and the infrared light projected into the panel is scattered elsewhere. This change in light intensity can be picked up by the detectors around the edge of the display.

 

A key benefit of the technology is that practically any object touching the screen will alter the scattering profile. This makes InGlass™ sensing more flexible than capacitive, which only works reliably with ungloved fingers or certain types of stylus. This makes the technology highly suited to industrial environments where the only option up to now for sealed displays was the traditional low-resolution, single-touch infrared approach. InGlass™ multi-touch technology can use the protective, transparent screen as an integral part of the design. It is also easy to integrate with existing LCDs – it does not need custom modules to be made, allowing for much greater variety in display choices for systems integrators.

Developed in conjunction with InGlass™ multi-touch specialist FlatFrog, Dialog Semiconductor’s DA8901 Smartwave multi-touch integrated circuit (MTIC) provides the control functionality needed to create large-display touchscreens, making it easy to integrate the technology into a new generation of products that extend the benefits of touch-based interfaces into many new markets.

There’s more information about it here: http://www.dialog-semiconductor.com/multi-touch