Keypads that utilize dome switches, silicone elastomer keys, or tactile switches rely on actuation force as a critical feature to define how much load is required to close the normally open switch. In this context, force is a vector acting normal to the keypad surface and is usually defined in grams (g) or pound force (lbf).
If you were to ask 5 separate people to explain the definition of keypad, likely you would receive 5 completely different answers that all center around the same basic concept. According to Wikipedia a keypad is a set of buttons arranged in a block or "pad" which bear digits, symbols or alphabetical letters (source https://en.wikipedia.org/wiki/Keypad). While this definition is correct, when communicating to a potential user interface supplier the term keypad requires further elaboration.
In this blog post you can view two videos that go into detail about the functionality of the human-machine interface (HMI) product sample and an overview of how capacitive touch membrane switches work. The transcription of both videos is also provided below. Take note that the transcriptions have been edited for better readability.
As capacitive touch human machine interface (HMI) assemblies become more popular, both designers and users are becoming more familiar with the technology as it replaces traditional mechanical HMI products. These capacitive touch HMIs can be used in extreme environments, with users wearing gloves, and can operate reliably for years.
Just as a mechanical HMI (membrane switches, tactile switches, etc.) relies on the overlay material properties to determine system function, capacitive touch HMIs rely on the overlay material properties to drive capacitive touch sensitivity and overall system performance.
When our customers are in the preliminary stages of launching a new SMART HMI project, they typically reach out seeking advice on the best way to start. With what can amount to a near infinite number of HMI design options and system feature combinations, brainstorming an embedded firmware project can quickly become overwhelming. Where does one begin? How does the firmware work? What level of detail is required now?
Recently I spent the weekend at a family member’s home and experienced two failures of everyday human-machine interfaces (HMI) devices that truly perplexed me. One was a collapsed dome switch on a spa controller; the other was a graphical display error on a touchscreen coffee maker.
Over the last 25 years, the evolution of touch screen technologies has brought sweeping changes to how society uses human-machine interface (HMI) products. Originally touch screens were small, monochrome, and required a stylus and single touchpoint to operate.
Manufacturing complete human-machine interface (HMI) assemblies can be a complex and difficult journey, which is especially true if it involves more than one supplier. This blog post mentions a few of the great advantages of being able to work with a single full service HMI supplier.
In all likelihood right now as you read this post, there is a smartphone somewhere on your person, on your desk, or otherwise within reach. These products have become much more than just a means to communicate with others.
When creating your SMART user interface design, the operating environment should be taken into careful consideration. Environmental contaminants, moisture, temperature extremes, UV radiation, and overall wear and tear from use in outdoor environments are factors that should be considered before determining material and component selection for your SMART user interface.