HMIs can vary quite a bit between manufacturers, applications, and user markets. Inputs range from capacitive or resistive digital buttons to physical buttons and voice control. Displays might be high-definition, high-resolution TFT LCD or high-performance OLED. Applications differ from next-gen automobiles for infotainment, in a high-tech tractor to monitor GPS position, or in a construction vehicle to monitor instruments.
Be it a field harvester, crane, skid steer, excavator, or any type of agricultural or forestry equipment, HMIs in these applications have recurring as well as application-specific design challenges.
HMIs must have high brightness, contrast and glare or reflection control for readability in any environment or time of day. Extreme temperatures cause materials to expand, contract, dry out, swell, or outgas over time; all of which affect HMI longevity. Add to the mix ingress contaminants, such as dirt, dust, and water, and it’s clear there are numerous weatherability challenges for HMI adhesives and sealing materials.
The various electronics and electrical components within the HMI have two unique operating challenges. First, they must withstand road conditions and vibration through everyday operations. These environmental factors are considerable for heavy machinery. They must also exhaust heat from internal electronics and the display module, which can compromise performance. To deliver the aesthetics and user experience consumers expect from phone and tablet displays, the HMI must also be thin, lightweight, and immersive, which means unusual sizes and contoured screens to fit within dashboards, mirrors or control panels.
There is also the issue of electromagnetic interference (EMI), radio frequency interference (RFI) and electromagnetic compatibility (EMC). New and more electronics networked into heavy industries increases the chances for signal interference or electronic crosstalk. Ensuring the right data is received and processed is key to the task at hand.
This is where foams, tapes and other materials with high-performance compression and electrical characteristics play an important role. These materials can ensure thermal and electrical contacts remain consistently connected, potential damage due to overheating is prevented, and HMIs are protected from short circuiting, contaminant ingress or mechanical failure from vibration.