touchscreen technology
Touchscreens for industrial control
Developments in touchscreen technology have made screens an increasingly viable option beyond popular consumer devices
By Ian Crosby , Sales and Marketing Director , Zytronic – www . Zytronic . co . uk
New developments in touchscreen technology are widening their suitability for industrial control applications . Enhanced sensitivity ensures that screens perform better than ever behind protective cover glass and with gloved hands . New controllers are also less sensitive to electrical noise in the environment , and attractive new features are emerging .
One touch technology , projected capacitive or P-CAP , is dominating the industrial touch control landscape . P-CAP is also the most popular technology in high volume phones and tablets ( see The Business Research Company ’ s report ‘ Touch Screen Market Globally 2015 ’).
This success has been driven by a compelling set of features including an effectively unlimited lifespan conferred by a resistant all-glass surface , edgeto-edge design capability ( with no requirement for bezels ) and high levels of sensitivity . These features also appeal to industrial control applications . The volume of sales in the consumer market reduces costs , but drives R & D investment leading to capabilities , some of which are also suitable for the industrial market . Examples include force recognition ( Z-axis detection ) and gesture recognition .
High sensitivity Fundamentally , the key attribute of P-CAP touch technologies such as PCT and MCPT is its high sensitivity . It can detect a touch through thick overlays , protective glass and even heavily gloved hands and therefore has an unsurpassed level of Z-axis sensitivity and control . Coupled with a well-designed touch controller it can offer a reliable and intuitive touch experience , responding precisely to up to 40 touches .
Although many instrument designers believe that users will only touch the screen with one finger at a time , multi-touch functionality can still bring advantages . For example , gesture recognition such as the pinch and zoom action popular with tablet users relies on the ability to recognise more than one touch point . Palm rejection , where a screen ignores a hand resting on the screen but still recognises and responds to an intentional touch , similarly requires multi-touch support .
Force sensing A further development as yet little used in instrument user interfaces , but with great potential , is force sensing . A common objection to touchscreens is that they don ’ t provide feedback in the way a mechanical button does , if a user is looking away . Using force recognition , a verbal message can alert the user to the option selected when the screen is touched lightly . The selection can be confirmed by pressing harder . So , for example , an instrument can say ‘ temperature ’, ‘ pressure ’ or ‘ time ’ as the user ’ s finger moves across the screen . Once the finger is over the correct option , a firm press makes the selection . This approach also allows partially sighted users to be accommodated .
Extending force sensing from handheld devices to larger touchscreens used in commercial and industrial applications is much more than a matter of simply scaling up the same technology . Most smart phones use capacitive sensors integrated into the display . This approach would be very costly if scaled up to a large screen , and is also incompatible
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