Since the emergence of touchscreens, user interface technology has experienced continued and rapid evolution in order to meet ever rising consumer expectations.
Projected capacitive touch sensing – detecting without contact – now enables multitouch and gesture recognition in most smartphones and tablets, creating a level of expectation amongst users of other devices.
However, smartphones have access to considerable processing power, which not all applications can afford from a hardware, software or power budget aspect. Applications such as access panels, simple keypads or thermostats, gamepads, remote controls and even wearable technology all present significantly different use-cases in terms of response time, resolution or cost. The flexibility to optimise a design is therefore crucial if the technology is going to transition successfully across multiple vertical markets.
Power consumption, in particular, represents a significant challenge for projected capacitive sensing (PCAP) in many applications. The relatively high power consumption of most PCAP solutions limits their use in low-power applications. Beyond smartphones, embedded devices can now offer battery lifetimes in terms of months or even years instead of hours. Assessing the power consumption and management is now an essential part of evaluating any PCAP technology, but through the combination of its eXtreme Low Power (XLP) technology and royalty-free source code, Microchip can successfully address the issue of low-power PCAP.
As an example, single-touch tap, swipe, swipe and hold, and double-tap gestures can be implemented using low-power and inexpensive devices. For example, a small sensor running at 2 V would consume just 15 A in active idle mode; when woken with a touch this rises to just 150 A when actively scanning. In a recent design example, this translated to more than two years battery life.
Remote controls, gamepads and other power-conscious devices could benefit from these advancements in PCAP technology and power management. As with all applications, there are sometimes performance trade-offs, but power, size and other characteristics can be managed to meet the low-power design requirements.
Flexibility is the next challenge to expanding PCAP into new markets; the rapidly emerging market trend of incorporating touch and gesture detection into devices beyond mobiles requires rapid innovation from developers. As a result, faster design cycles require progressive and flexible PCAP touch controllers and sensor design options.
Traditional PCAP solutions have long design cycles with rigid implementations, consisting of an ASIC-style touch controller and fixed sensor design. Many suppliers of touch technology offer dedicated black box, ASIC-style touch controllers that match up with specific touch sensors; they work for their dedicated application but the developer has limited design flexibility.
These fixed solutions don’t allow for code modifications if, for example, a small change is needed during the development phase. This means that any changes to the sensor design could constitute a new design, requiring extensive work with the technology supplier. Such closed designs also prevent the integration of code for other functions in the same controller, such as driving or controlling LEDs to extend the functionality. Being locked into a closed solution can introduce significant penalties for manufacturers who need to react quickly to market demands.
Developers shouldn’t be ‘boxed in’ by hardware or software with their PCAP solution; one approach to meet the challenge of maintaining flexibility and supporting design changes is to empower designers with source code access and the tools to allow them to independently customise their PCAP technology, in order to create optimised solutions. This design flexibility allows customers to manage their touch-interface solutions to enable fast and targeted modifications on their own timetable, without depending on external vendors.
Microchip has taken a unique approach to addressing customer needs when it comes to selecting the right PCAP solution, by offering both flexible black-box touch controllers and royalty-free source code options that can be used across its standard portfolio of 8-, 16- and 32-bit PIC microcontrollers. This allows developers to optimise their design for features, performance and cost, while providing a migration path with many options to help keep future design paths open and system costs down.
The sensor is the third challenge in enabling other markets to adopt PCAP technology. Touch sensors in the mobile market are often proprietary designs with limited access to supply chains. This restricted access presents a sourcing challenge as well as functional uncertainty for those trying to make their own custom solutions.
Fortunately, the recent development of various types of inexpensive projected-capacitive touch sensors that are easily available and manufacturable now enable designers to start working on these new market segments with PCAP-enabled designs.
Some examples of these sensor types include touch pads and flexible sensors. Typical touch pads are inexpensive sensors based on a PCB that can be used under a plastic overlay, similar to the look and feel of touch pads on laptops. These standard sensor designs provide the desired smooth surface feel, with tap and swipe touch response, which are applicable to many applications such as gaming pads, light switches, automotive consoles and remote controls.
Other sensor options include flexible PCB sensors and printed sensors created using conductive inks. These flexible sensors offer options for designs with curved surfaces, or backlit keypads that may need cutouts for LED lighting. Printable and transparent conductive inks can now offer an inexpensive and
manufacturable touch sensor solution for wearable electronics, a rapidly emerging and highly innovative market segment.
The use of touch sensing beyond its traditional smartphone and tablet application space is driving manufacturers and developers to innovate at an increasingly rapid rate. Adopting a PCAP technology that supports this rapid evolution may prove essential if the technology is to meet its full potential and successfully revolutionise modern electronic devices across all vertical markets.
For more information contact Tempe Technologies, +27 (0)11 455 5587, willem.hijbeek@tempetech.co.za, www.tempetech.co.za
| Email: | willem.hijbeek@tempetech.co.za |
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