Advances in Capacitive Touch Panels

Mike Logan – Display and Input Technology Manager – andersDX

Although capacitive touchscreens can normally respond when the user is wearing thin latex or rubber gloves, demand is now growing for touchscreens to offer an acceptable user experience for wearers of thicker gloves, such as cut-resistant industrial gloves worn to comply with safety regulations, or ordinary leather or synthetic gloves, to allow wearers to interact with industrial automation or machinery, smart signage, access-control panels, or outdoor point-of-sale equipment, to name a few.

Often, these systems are installed behind thick cover glass for protection, for outdoor use or other applications where harsh treatment is expected. In the past, typical project requirements have called for cover glass up to about 1.8mm thick, whereas a growing number of customers today are looking for a touchscreen to operate behind glass up to 4mm or even 6mm thick.

A large part of the solution is in the performance of the touch controller, rather than the touch sensor itself. Moore’s Law improvements in processing performance enable the latest touchscreen controller ICS to deliver a better combination of sensitivity and response time than preceding generations of devices. The latest knowhow for laying-out ITO (indium-tin oxide) electrode patterns, also allows design tools to determine patterns that are better-optimised for touchscreens to be placed behind thick cover glass or to accommodate users wearing gloves. It may soon be possible to create touchscreens that can be tuned for optimum performance with a certain type of glove, such as application-specific industrial gloves.

System Approach Recommended

Whether engineers designing touch-enabled user interfaces into their latest projects can satisfy application requirements for thick cover glass, or end-user demand for response when wearing gloves     depends on achieving a suitable combination of ITO pattern, controller performance, and cover-layer properties including optical clarity and thickness.

Of course, there are several interdependencies between the components, materials and settings, and these should be considered from a system perspective at an early stage of the project. The ITO pattern that forms the array of sense and drive nodes, which sets up the capacitances for touch detection, influences the signal-to-noise ratio and, together with the touch-controller firmware, determines the touch threshold. Both factors influence the permissible cover-glass thickness, and potential performance if the user is wearing thick gloves.

The graphical display behind the touch sensor can couple noise into the capacitive touch-sensing layers and therefore the ITO pattern can determine the sensors susceptibility to EMI.  Including a ground shielding layer in the touch-sensor stack-up can reduce noise emanating from the LCD and entering the sensor’s circuitry.

In addition to considering the ITO pattern design, the firmware of the selected controller IC can be adjusted to suit various types of cover lenses to optimise system performance. If the sensitivity needed to allow touch response with the anticipated type of gloves cannot be achieved using glass of the intended thickness, the designer may consider trading-off some physical resilience by specifying thinner glass in exchange for increased sensitivity. Alternatively, a specialised type of glass, such as Gorilla Glass, could be considered instead. Gorilla Glass is both tough and thin: a combination that is widely appreciated in the mobile industry. Thanks to the economies of scale of the mobile industry, it is available at relatively low cost for standard screen sizes up to about 7 inches.

Firmware in conjunction with special algorithms designed to filter out unwanted EM noise are critical to achieving the desired touchscreen performance and one should always be prepared to make allowances to fine tune the FW if necessary, should various elements of the display module, including cover glass, touch sensor, bezels, backlights, and adhesive layers require modification. Further fine-tuning of the FW settings may be needed when the touchscreen is integrated with the circuitry that comprises the remainder of the overall system.

Early Decisions Guide the Project

Generally, touchscreen performance parameters are wider today than at any time in history. High performance and almost seamless user experiences, including good response to users wearing gloves or fast-acting single- or sometimes multi-touch response from behind thick and robust cover glass. Today’s touchscreens can be designed to operate reliably in extremely cold environments, in wet or humid conditions, or where harsh treatment or frequent heavy impacts against the cover glass can be expected.

The key to successful design is to establish an achievable specification at the beginning, usually working with an experienced technical partner to identify the best combination of controller chipset, touch panel, cover glass and other key components. Making the right choice early is important to ensure the required features can be delivered, and can help simplify fine-tuning and avoid unexpected problems later in the project.

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Why FM must utilise IT to drive strategic change

asta2-Michael-McCullen-Exec-ChairmanBy Michael McCullen, Executive Chairman, Asta Development

We are told that UK business is experiencing ‘economic recovery,’ however, while confidence is rising, the business community shows no sign of returning to its pre-crash complacency. Economies of scale are the aim of expansion, efficiencies are the goal of restructuring, and there seems general acceptance that future uncertainty and rising energy costs are the only things that business can really count on. A new business culture is emerging within which constant cost minimisation is the norm and is becoming as central to business strategy as the pursuit of sustainability and social responsibility.

As businesses continue to streamline operations and plan investments around efficiencies, one spotlight will always fall on the cost of real estate and its management, which forms a significant proportion of operational costs. Despite the fact that FM has enjoyed an increased profile in recent years, individual FMs and FM organisations alike must increasingly demonstrate their value and contribution to driving efficiency and performance — or risk becoming the target of efficiency drives. FMs face a choice of whether to step up to become a true strategic business partner or remain as a service — a challenge acknowledged repeatedly in major FM reports by organisations such as RICS[1] and the BIFM.

FM is in a strong position to add strategic value; it is in possession of detailed and valuable information about the very environment in which the business operates. When information is power, information technology is an inevitable and critical component. With the right tools, data can be turned into FM business assets. IT has always been a factor, but project planning has often been spreadsheet-centric, facility cost management often divorced from core financials, building control systems rarely integrated into other IT, and even Computer Aided Facilities Management (CAFM) systems are often only used as glorified records filing systems. FM has had a piecemeal approach to IT adoption.

FM’s role as one of the stakeholders in Building Information Modelling (BIM) is beginning to change this. For the first time, facilities will be commissioned with a full 3D modelling history linked to their planning and construction project schedules. FMs will be expected to put these valuable assets to work: link them to building management and evolution, manage and plan the maintenance of assets in a 3D environment and exploit stored information about building infrastructure and services from this rich data resource. BIM-enabled systems will go further than standard CAFM: not only to collect and automate aspects of building data, but to utilise rich, dimensional data and sophisticated planning and scheduling capabilities to:

  • Work smarter to schedule and plan activities and resources, projecting potential scenarios and creating flexible plans
  • Demonstrate strong and appropriate utilisation of people and equipment – supporting and justifying resource investment and replacement
  • Build powerful, useful and business-aligned performance measures as well as track traditional FM measures
  • Schedule work aided by intelligence about infrastructure and services inside the very fabric of buildings — without the potential delays and cost of surveys
  • Deliver repair-and-replace services more predictably and with the ability to demonstrate cost effectiveness and business value
  • Show how FM actively prevents issues and interruptions with forward analysis of costs and dependencies
  • Take control of the energy and waste reduction agenda – embracing, creating and driving sustainability programmes
  • Partner with functions such as IT, to build the business case for the right technical programmes, or with HR to show how environment enhances productivity and wellbeing
  • Influence building design as part of a design review team: to create buildings that are easier and cheaper to maintain without compromising design objectives

Going forward, FM must actively embrace 3D planning: not only inheriting BIM-enabled plans and models, but becoming directly involved far earlier in the development timeframe and delivering expert insight pre-construction to create better buildings and avoid costly mistakes which could cause future maintenance and FM issues. A  new generation of tools is already emerging which is bringing modelling and planning together using common data formats like the IFC standard, which is being adopted by an increasing number of software vendors. Whichever way FM chooses to approach IT, it must do so more rapidly than before in order to evolve as a business function. If it isn’t a clear part of the cost efficiency solution there is a risk it will be seen as part of the problem, but with stronger IT engagement and the right tools, it can show its readiness to contribute to improved business and design processes, as well as long-term building sustainability and efficiency. It can demonstrate that it is not just a management function for buildings but a true part of the constant drive for greater business efficiencies.

Michael McCullen, Executive Chairman, Asta Development

Michael McCullen was one of the founders of Asta Development, which was formed in 1988, and he has played a key role in driving the profitable growth of the company, which was acquired by Eleco plc in 2006. Michael is Executive Chairman of Asta and sits on the main board of Eleco. He holds a Computer Science degree (Manchester) and an MBA (Warwick).

[1] http://www.rics.org/Global/Raising_the_Bar_II_29_01_14_dwl_pc.pdf

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