In the past, the operation of panel PCs using a touchscreen was generally only possible using one finger per single touch in the case of industrial applications. Thanks to its operating options, multitouch offers great ergonomic comfort with two or more fingers. We place the focus on today’s most widespread analogue-resistive touch and PCT technology.
In principle, only one touchpoint can be registered with this technology due to its design. New solutions also enable full multitouch functionality. Here the entire screen area is divided into several zones, each representing a single touch with individual connections to the controller. Any type of touch pen can be used to operate the screen; even gloves do not restrict functionality in any way.
From a hardware perspective, projective capacitive touch (PCT) already has multitouch capability; its grid structure can register several touchpoints in parallel. This allows shift and rotary motions to be executed ergonomically on a large display even over extended distances. The sensors are protected on the reverse side of the glass with capacitive touchscreens. This technology is particularly useful for environments in which stringent requirements apply to the systems’ cleanability – for example, in the pharmaceutical industry or in medical technology.
Nowadays almost every touch display comes with ITO sensors (indium tin oxide). For displays of up to 15 inches, ITO is coated on PET film; glass substrate dominates for larger formats.ITO is extremely conductive, almost transparent and therefore not visible in the display.
In the case of DITO sensors (double-sided ITO), the top and bottom sides are ITO-coated. They also feature an extended temperature range and display very linear behaviour.
Tiny silver particles are employed as conductive material in SILVER-NANOWIRE technology. As a result, you can have extremely thin, malleable touch film with excellent capacitive properties that guarantee minimal reaction times. In addition, you get a much narrower bonding area of the touch sensor to the terminal lug. The sensor is suitable for applications with an ultra-wide viewing angle, extreme brightness and an extended temperature range. t works in wet and dirty conditions, and gloves can also be used.
The touch controller affects approx. 40 parameters which influence the touch behaviour for optimal operation – for instance, the sensitivity of the touch surface, the distance to the screen at which the finger triggers a function and whether you can use gloves to make entries.
The availability of an operating system – prepared subject to the controller and integrated via standardised interfaces with any multitouch hardware – is crucial. Windows 7, Windows 8 and Linux offer full multitouch support in various forms. In addition to multipoint operation, they also support gesture controls.