The growth of PCAP technology: Infinite Touch
13 September 2017
The touchscreen has been used for many decades as an input device for computer systems, and there have been different types over the years, including Infrared, and of course, Resistive. This piece looks at the new alternative: the Infinite Touch.
All of these technologies had the sensor part of the touchscreen on the surface so you had to physically touch the sensor, or in the case of IR, break an array of beams across the front of the surface.
The fastest growing technology is Projective CAPacitive or PCAP touch. This allows the sensor to be positioned on the rear of a glass substrate, and as the capacitive ‘finger’ approaches the surface, the touchscreen can sense the finger approach. The controller is then tuned to the thickness of the glass and its noise surroundings and the touch point will then be determined when the finger touches the surface of the glass.
Unlike traditional surface capacitive touchscreen technology, this will also allow for a gloved finger to be used to activate the touch via tuning of the controller. Previously this was achieved through resistive technology which had a number of disadvantages, including reduced light transmission, the need for recalibration over time/temperature and susceptibility to surface damage – as the front was a flexible polyester layer.
Although the PCAP technology has been available for nearly two decades, the iconic tablet market has made PCAP the technology of choice, due to its modern-looking aesthetics and the ability for customisation to offer a true flat edge-to-edge glass solution. The majority of touchscreens will have a HID (Human Interface Device) controller which will allow for a simple Windows plug-and-play, eliminating the need to load complex drivers. The technology also forms as many as 40 simultaneous multi-touch points, although most controllers specify 10 multi-touch points, which in most applications is more than sufficient.
Any touchscreen will need to be fitted to the display. Traditionally the most common method is via Strip Bonding where a border of double-sided adhesive tape is placed between the bezel of the LCD and the touchscreen. The second method is through Optical Bonding: this is the process of applying a silicone layer between the front of the glass and the rear of the touch sensor, eliminating the air void. This has the advantage of making the solution stronger and reduces condensation with rapid changes in temperature. The main advantage, however, is that this stops the internal reflected light between the layers and increases the contrast in high-ambient light conditions. Display Technology uses their VacuBond process to optically bond displays in a clean room environment. Allowing the manufacturer to fit the touchscreen reduces the risk for the end customer. It also stops the chance of misalignment and the need for removal/replacement, which then gives a high chance of damage.
The Infinite Touch range
Display Technology Ltd have utilised this PCAP technology to create their Infinite Touch range. This is the process of optically laminating the touch sensor to the rear of a bespoke cover glass, which gives a completely unique solution for the end client. This customisation includes: glass shape, rear screen printing in single or multiple colours, holes in the glass, and different glass thickness/finish. DT can also laminate ultra-thin Guerrilla/Xensation glass. These bespoke solutions are possible at low quantities with minimal setup costs.
For more information on Display Technology products and solutions, visit www.displaytechnology.co.uk.
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