Display Technology
capable of supporting most gesture recognition and multi-touch software. Two variants of PCT sensors are currently available. An ITO-based solution suits higher volume applications that require a rugged interface with a relatively small screen size, such as white goods and industrial vehicle telematics. Although this senses in the self-capacitive style, it uses the same basic manufacturing processes as mutual capacitive sensors designed for consumer electronic applications. For large format and lower volume applications, a solution based on copper is offered. Here, the capacitive matrix within the sensors is made of 10 micron diameter copper electrodes. One advantage of this material is its extremely low resistivity (10 times less than ITO) allowing touch detection without noticeable degradation of sensitivity, even on screens larger than 80 inches. Another advantage of using copper electrodes is that they can be deposited directly onto the rear glass surface without the need for photo masks – this means that new
Redmond, WA). A wrap-around ZYBRID touch sensor was supplied for its conceptual 10 display multi-monitor workstation, called the Spatial Desk, operated through a single PCT touch- enabled surface and used to demonstrate the latest Microsoft technologies to key customers. With a choice of materials and of mutual or self-capacitive sensing p-cap methodologies, OEM interface designers have a toolkit at their disposal that allows them to create a touch screen for any application, depending upon factors such as the deployment environment, touch performance, physical screen size and volume required.
An example of an unusual application solved by p-cap sensing occurred when advanced user interface specialist Sunvision Technology was asked to create interactive dining tables for the exclusive Taipei restaurant Mojo. For this project, it was necessary to make the wooden tables touch sensitive. This required a technology
presenting interactive menus on the touch- enabled surface. With the touch sensors hidden from view, when coupled with software specifically written for Mojo by Sunvision, diners are now able to interact with projected images, scrolling through dining options, placing orders, playing games and messaging diners at other tables.
The ability of PCT to enable far larger
screens than can be realized using conventional mutual capacitance alternatives is demonstrated by its increasing use by digital signage specialists
scale) normally employed in the production of mutual capacitive p-cap screens mean they will probably remain best suited to small format, high volume designs. In more demanding, ruggedised applications, which require volume flexibility and large form-factors, alternative approaches are essential. As a result, p-cap sensors derived from advanced self capacitance sensing such as PCT are likely to remain at the forefront of such applications as industrial controls, self- service terminals and medical devices. This technology is already delivering touch
Figure 3: Zytronic touch sensors specified by Infinitus for large format digital signage application
Figure 2: PCT brings multi-touch table service to Mojo restaurant
designs can be quickly created, tested and manufactured with minimal effort. Furthermore, the ductility of copper means it can also be applied onto curved planes. Microsoft Corporation made good use of this capability when developing a touchscreen for its Envisioning Lab (at the corporation’s global headquarters in
with extremely high levels of Z-axis sensitivity and the capability to detect touch through the wooden surface of the dining table. With this challenging brief, Sunvision chose to embed Zytronic’s 22- inch ZYBRID PCT sensors behind each table top, linking each to a computer-controlled projector mounted above the table
such as Infinitus. Here a 65-inch version of the ultra-rugged ZYTOUCH product was specified for the iMotion high-definition digital signage systems designed for use in outdoor, public environments (such as ski resorts, plazas and amusement parks). Design engineers in a broad range of markets outside of consumer electronics, are increasingly keen to adopt similar levels of touch interactivity already enjoyed in the latest hand held tablets and smart phones. In the process, the limitations of conventional mutual capacitance techniques become apparent. The nature of the materials used and their manufacturing processes (with resulting economies of
interaction in products that simply would not have been possible using other methodologies and has the potential to enable further innovation in the future. The continued improvement in p-cap
controller ICs coupled with sensor developments using printable conductive inks and nano-materials are likely to extend the capability and use of this versatile touch technology family further still.
Zytronic |
www.zytronic.co.uk
Ian Crosby is Sales & Marketing Director and Dr. Andrew Morrison Technical Director, Zytronic
www.cieonline.co.uk
Components in Electronics
May 2013 33
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