FEATURE SENSING TECHNOLOGY
MAKING SENSE OF TOUCHSCREEN technology amidst all the options
Which touchscreen technology should system integrators choose for their new designs and how does sensing technology come into play? Brendan O’Reilly, Product Manager at Display Solutions investigates
s consumers in such a ‘digital’ generation, we have developed certain expectations when it comes to touch technology. Not only should monitors be able to be touched, they should offer bespoke information, and the ability to turn pages, flick through images, zoom in and out, amongst various other functions. A screen that doesn’t offer some kind of interaction is not appealing to consumers. The big challenge for system integrators, however, is to develop touch terminals and systems that provide customers with a solution that suits their needs. There are various pointers when navigating touch technology. Questions that need to be asked include; what do you want your touch screen to do? Where will it be located? How big does it need to be? How long will it be operational? In what environment will it operate? and most importantly, what gesturing and touch points do you need?
A
PCAP – HOW DOES IT WORK? Projected capacitive touchscreen technology (PCAP) is the most sought after technology when looking at multi- touch applications. It has many benefits over other touch technologies, in particular, a multi-touch capability, extreme durability with up to 250 million hours lifespan and superior optics with over 90 percent optical transmission. Comprising three major components; the sensor glass, the cover glass, and a flexible printed circuit (FPC) to the controller IC, this touch technology is both robust and reliable. The sensor glass is made up of a series of electrodes that are configured into rows and columns that are read’ one by one to get an exact reading or count. These electrodes are made of a transparent conductive coating called indium tin oxide (ITO). Each electrode is routed back with a metal trace to a connection point where the FPC can be bonded. The cover glass is optically bonded with an optical clear adhesive on top of the sensor glass, burying the electrodes within the stack of the lamination. The
26 OCTOBER 2014 | ELECTRONICS
problems with scaling up the optical sensors, hand and lap devices have been the limit of PCAP monitors for several years. However, due to extensive R&D, developers are now able to offer the technology on bigger screen sizes, but still keeping the accuracy and reliability found on smaller screens. Historically, PCAP has been an expensive option, but it is becoming more attractive price wise with the introduction of ranges such as DisplayTouch from Display Solutions, which offers cost-effective solutions, available in screens up to 42” guaranteeing an accurate and precise user experience. The most recommended type of touch technology if you want a touchscreen capable of supporting two point touch application at a lower cost is surface acoustic wave (SAW). SAW has been known to have problems with moisture and surface contaminates, which made it unsuitable for industrial applications. However, this issue has been solved by adding a layer of glass to protect the screen from dust, water and scratching. Infrared (IR) and optical technology is
suited to larger size screens, so can be seen in digital signage, wayfinding and public information applications. There is zero activation force needed which means it is very convenient for retail and offers great light transmittance with no distortion of images, even in screens of up to 85”. It can incorporate multi-touch of up to 10 points and can be used in harsh environments, giving a strong, waterproof option with great longevity, even in strong light. When investing in a type of touchscreen
cover glass serves as a dielectric between your touch and the electrodes of the sensor glass. It also acts as a barrier layer, protecting the sensitive electrodes from the environment and potential damage. The controller continually scans and
monitors the capacitance of the electrodes. When a finger touches the surface of the cover glass it pulls a small charge from the electrodes and using complex algorithms the controller can determine the exact location of your touch, the results are extremely precise.
MULTI-TOUCH BENEFITS PCAP has been around for some time, but it is only recently that this type of touch technology has moved away from phone or tablet size form. Due to
Figure 1:
Litemax PCAP touchscreen technology in use at a bus stop in Aberdeen
always extensively research the reliability, durability and performance of the product. Check the technology matches the end users needs and suits the environment in which it will be used, in terms of elements, types of users as well as touch functionalities needed. With all the different types of technologies available, to suit a huge variety of industries and applications,, it is guaranteed that there will be a touchscreen technology with the right level of ‘sensitivity’ available to suit every type of environment.
Display Solutions
www.displaysolutions.co.uk 01480 411 600
Enter 213 / ELECTRONICS
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