Display Technology

HMI and the rise of touch

Clive Dickinson, business manager for Displays at GTK UK, examines the progression of touch display technology over the last half-century, highlighting the functionality millennials want, and providing guidance on how to cost-effectively design it into new products


here are many milestones in the development of the Human Machine Interface (HMI), beginning with Sir

Clive Sinclair’s ground breaking keyboard design and vacuum fluorescent starburst character display, which signalled the first step in connecting the user to a complex electronic device, with no prior knowledge of how to use or programme it. Fast forward fifty years and we find children today are introduced to high

quality, highly complex user interfaces almost from the moment they are born, as evidenced by a video recently circulated on social media showing a baby attempting to zoom in on a picture in a magazine with two fingers.

So why does that matter if I’m designing a fire alarm or a wall thermostat? The millennial comes in for a lot of flak

but there is no escaping the fact that today’s young are tomorrow’s customers. This generation has grown up with an amazing ability to understand complex products; they wouldn’t countenance getting on their hands and knees to programme the video recorder. If they can’t connect to it with their phone and programme it from anywhere in the world, they won’t bother. They expect a level of in-built connectivity and functionality, and for your product to be usable immediately, flexible and adaptable to their needs. With regards to aesthetics, they expect a sleek, beautiful interface that is strong and tough, fast to respond and flexible. In the time it would take a Ferguson TV to warm up, they have fired up their iPhone and are already five minutes into Game of Thrones. It’s not just fashion, it’s a serious issue. Your product might be competent and

carry high levels of approvals but if it looks clunky and out of date, they won’t buy it, turning instead to something that looks and feels how they expect.

But I can’t afford a fancy colour touchscreen on my budget Designers often regard this kind of HMI as for high volume consumer goods only, but this isn’t true. It’s possible to source custom designed touchscreen HMIs in low volumes and at a tolerable cost. In fact, if the designer takes a holistic approach, it’s likely to greatly enhance the functionality of your product and take cost out in other areas to offset the cost of the HMI.

But my electronics can’t drive this kind of device There are many amazing solutions out there today. The introduction of ARM’s Cortex product ten years ago revolutionised the microcontroller market, enabling hitherto difficult and expensive features like Ethernet, Wi-Fi, gyro/accelerometer, USB etc. and at low cost to acquire. These devices are reputed to achieve 100Mbps for one US dollar in high volume and that benefit has filtered down into the industrial market. Single Board Computers (SBC) with operating systems have proliferated at an amazing rate, the most famous of which is Raspberry Pi and is reputed to be shipping at 15,000 units a day. The recently launched Compute Module is aimed at the industrial market and offers 700 MHz quad-core performance with amazing levels of support and integration, all for $25. This device can drive a touch HMI directly, with no additional cost and no engineering time - just connect it up and off it goes.

So how do I go about getting a touch HMI? Firstly find a TFT display of a suitable size for your user and to fit in your product. These are available from sizes small enough to fit in a watch, up to a metre across, but popular sizes like 7 inches and 10.1 inches are a good choice because of multiplicity of supplier and wide usage. Then decide whether you need any enhancements. For outdoor applications, sunlight readability; for walk past applications, you might want all round viewing angles or high resolution. Some

12 May 2019 Components in Electronics

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