Appliance Design - February 2009 - (Page 12)

CONTROLS & SENSORS TOUCH Force-sensing provides alternative touch–control method. by anders molne and david griffith Anders Molne is vice president of product operations and David Griffith is vice president of engineering, F-Origin, Morrisville, N.C. 12 applianceDESIGN February 2009 t first glance, touch-based interfaces would seem ideal for a variety of residential and commercial appliances. The ability to reconfigure appliance controls in software, combined with the potential for improved mechanical and environmental resilience seems very promising. Unfortunately, existing touch technologies have often fallen short. All of the common touch technologies in use today have significant weaknesses in durability, manufacturability, or cost. These weaknesses make the integration of touch technology much more challenging for the product designer. There are four common types of touch technology: resistive, capacitive, standing acoustic wave (SAW) and infrared (IR). Resistive technology is commonly found on point-of-sale devices like the electronic signature pad at a grocery store checkout. Resistive touch screens rely on a thin film that is applied to the touch surface. The technology is relatively inexpensive to implement, but it’s also fragile. Not only does the surface film degrade the optical A FORCE clarity of the display, it wears out. In high demand situations, resistive touch screens can fail quickly. Capacitive touch screens, such as the one found on some appliances and mobile electronics, are generally more robust than their resistive counterparts. However, the manufacturing process is complex, resulting in low yields, high prices, and an inability to reliably manufacture larger touch screen devices. Capacitive systems typically require the use of a finger as an input device – most cannot detect a stylus, gloved finger or other object. SAW and IR devices use surface mounted components that project either an acoustic wave or an infra-red beam across the touchscreen area. Such systems can be much more robust than either resistive or capacitive systems, but they are dramatically more expensive. SAW and IR also impose more product design constraints, as the screen bezel has to be prominent from the screen and large enough to accommodate the necessary electronics. Lastly, SAW and IR can suffer from blind spots created by on-screen contamiwww.applianceDESIGN.com http://www.appliancedesign.com

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Appliance Design - February 2009 Contents Editorial Shipments/Forecasts News Watch Force-Sensing Technology Offers Designers an Alternative Approach to Creating Touch-Control Interfaces A Flammable Vapor Sensing Technology that was Originally Developed for use in Water Heaters has Evolved for use in a Broader Array of Applications Latches, Hinges, and Slides Must Reliably Secure Parts Together, Sometimes for Hundreds of Thousands of Cycles. Beyond their Utilitarian Functions, They Can Also Change Consumer Perceptions Elastomeric Electrical Connectors Can Solve Space Constraint Problems in Electronic Products and Provide Some Cost Advantages as Well A Multi-Layer Ceramic Capacitor with a Novel Electrode Design Can Suppress Electromagnetic Interference, Improve Circuit Performance, and Reduce the Number of Needed Components Design Marts Association Report: AHRI Advertisers’ Index

Appliance Design - February 2009

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