What Kind of User Interface is Your Best Option?

Written by Epec Engineered Technologies
Posted on October 1, 2015 at 1:42 PM

As a leader in user interface technology, we frequently get asked the question; what kind of user interface is the best option for my application. Human Machine Interface (HMI) assembly designs are dependent on the application, housing, and the environment they will be used in. Choosing the right option and material is a key component.

In the past, user interfaces or more commonly known as membrane switches, had the dependency of utilizing a separate circuit board. For more reliability you can now incorporate the circuit board into the full user interface assembly. There are multiple options for your application and why one or two may be a better choice for your project.

Basic Membrane Switch Style User Interface

Everyone should be familiar with a microwave and/or dishwasher and the control panel. That is a perfect example of a basic membrane style switch. While this type of user interface is low cost it also has some design restrictions that others HMI types do not. Such as, they require a hard surface to mount onto in order to function correctly. They also have limited capability for embedded components and the connection is limited to 1mm pitch spacing.

Basic Membrane Switch Style User Interface

Basic Membrane Switch Style User Interface

 

Advanced Membrane Switch Style User Interface

An upgrade to the microwave control panel example is the printed circuit board (PCB) based user interface assembly. In these PCB backed style designs, embedded components are only limited by the overall size. In the past, PCB’s were much thicker but as technologies increase there are now circuit boards as thin as 0.010”. This allows for more design options while keeping a low profile and helping to lower the cost of the overall project. Using a PCB backed option also allows for more flexibility in trace width and can achieve a connection of 0.5 mm or less. If a tail is required it can be used as a connector or it can be soldered to the PCB. The housing in which the circuit board will mount into must allow for the final assembly to lay flat with clearance for the user interface.

Advanced Membrane Switch Style User Interface
Advanced Membrane Switch Style User Interface
 

Flex Circuit Board Style User Interface Assemblies

If you’re looking for a solution that allows for flexibility similar to a basic membrane switch then a flexible PCB based switch may be for you. Using a flex circuit board allows for embedded components much like the rigid PCB based designs. Additionally, this design allows for the ability to form to your housing and the tail is an integral part of the circuit.

Rigid-flex PCB HMI designs have fundamentally changed the industry by combining all of the value of a printed circuit board and flex PCB based options. It also allows for the incorporation of multiple switches on the same circuit located all over the housing which helps make the design smaller and more cost effective.

Flex Circuit Board Style User Interface Assemblies

Flex Circuit Board Style User Interface Assemblies

 

Don’t Forget About the Graphics

Something else to consider is the appearance of the graphic overlay or top layer of your switch. Utilizing robust designs will give the appearance and feel customers may want to achieve through digital or screen printed overlays as well as plastic and rubber buttons. Backlighting or luminescent paint options can also be incorporated into any designs as well as touch screens and LCDs.

User Interface Assembly with Graphical Plastic Buttons

User Interface Assembly with Graphical Plastic Buttons

 

Conclusion

In conclusion deciding what user interface type should be used can be difficult depending on our application and cost factors. It is best to get expect advice from the start of your project as the human to machine aspect can sometimes be the most important component.

Our state of the art facilities offer a complete range of high reliability HMI technology with the ability to manufacture your entire product from design, prototype, to production.


Topics: User Interfaces


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