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EETE DECEMBER 2012

DESIGN & PRODUCTS DISPLAYS & INTERFACES Specifying touchscreen displays for industrial applications By Dieter Kiermaier These Days, user frienDly touch applications have be- touchscreens can be cleaned come indispensable in consumer markets. Touchscreens are and sanitized thoroughly with also in high demand for applications ranging from automation little regard for acids or cleaning processes to industrial instruments and controls or medical agents). The protection against devices. Touch displays offer a variety of advantages over tra- condensation is also guaranteed ditional screen interfaces. They are less susceptible to damage in areas of high humidity. The from dirt and debris than other input units like keyboards or average storage temperature range is -40 to +95°C with an trackballs. Additionally, touchscreens are far more flexible in operating temperature range of -30 to +85°C. usage. When talking about industry requirements, terms like “pro- Glass/glass touch technology is perfectly suited for medical tection class iP65,” “neMa 4,” “high electromagnetic compat- and industrial applications. additionally, the look of glass/glass ibility,” “Ce characterization,” “intended for continuous 24 touched is customizable with a printed bezel that achieves a hour operation” and “high ambient temperatures in operation” true flat surface that is reminiscent of the the look and feel of are frequently used. Depending on the type and location of the apple’s iPad. industrial usage, the touch display has to fulfill many, if not all of these requirements. in outdoor or industrial environments, ITO-based (indium tin oxide) Projected Capacitive Touch electronics have to be protected against externals like dust, dirt, Systems (PCAPs) are currently available in sizes up to 32”. Their extreme temperatures and humidity; therefore protection class major advantage is that the capacitive sensor layer will func- iP64 – or even iP65 with protection against water jets – are tion through protection glass with thicknesses of up to 5mm necessary. This protection is accomplished mainly by means with no effect to image clarity - see figure 1. PCAPs also offer of customized, hermetically sealed front integration into an true-flat glass front areas, which are easy to clean and resistant enclosure. “neMa 4” requires additional protection against rain, to environmental impacts. specially hardened cover glass (i.e., snow and sleet. Gorilla Glass) makes ruggedized customization an easy option. PCAP touches typically offer two-finger operation (dual touch), A number of touch technologies with new developments enabling operation with up to 60 fingers The market offers several different touch technologies, for use in (multi touch). For applications in public areas where vandalism diverse industry applications. 4-wire touch is a resistive touch- may occur (display windows, automated or information termi- screen, for which ease of integration is key. frequently, control- nals, etc.), Zytronic offers vandal-proof touchscreens that have lers for 4-wire touches are already integrated into the control a 20mm thick protective glass in sizes up to 82”. computer, making it a cost-saving option. The main advantage Analog Matrix Real Touches (AMR) touch systems combine for industrial applications is that the 4-wire touch responds to the advantages of resistive technology like simple integration, contact from any kind of medium (finger, stylus, glove, etc.) EMI (electromagnetic interference) shielding and can be oper- Resistive 5-wire touch sensors offer the same control options ated with glove, stylus, finger and more, while offering the multi and advantages as the 4-wire technology, with the added bonus touch options of PCaP touchscreens. aMr touches are the of longer life cycles (up to 35 million touches), as well as high ideal solution when cost-competitive multi touches are needed. accuracy and stability towards drift, regardless of screen size. Making the appropriate choice Resistive glass-on-glass (glass/glass) touch is based on When selecting the appropriate touch technology for applica- 4-wire technology, which it broadens with additional features for tion, the advantages of the technology have to be adjusted to required industrial usage. In comparison to film-on-glass (film/ the requirements of the industrial application. glass) systems, glass/glass technology has a longer life span and improved image clarity. Glass is the material on the user side (outside) as well as on the operator side (inside), making glass/glass touchscreens particularly scratch resistant. use of highly transparent glass substrates reduces the diffraction of incoming light and provides a distortion-free view of the display and improved transparency. Outdoor usage benefits from a po- larization filter on the glass substrate of the operator area. This reduces inner reflection between the substrate and the LCD. By using glass, the reliability of the touch panel is improved and more durable than that of foil/glass elements (glass/glass Dieter Kiermaier is responsible for technical product marketing at Distec, part of the Data Display Group - Scheme of Projected Capacitive Touch Systems PCAPs www.datadisplay-group.com Source: Data Display Solution 24 Electronic Engineering Times Europe December 2012 www.electronics-eetimes.com


EETE DECEMBER 2012
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