If you keep up with our blog here at Nelson Miller, you’ve probably heard of human machine interfaces (HMI). They live up to their namesake by offering an interface through which a human operator controls one or more machines. HMIs are used in a wide range of applications, some of which includes industrial factories, offices, retail stores and more. While most people are familiar with the general definition of an HMI, few know its components. So today we’re going to take a closer look at the different components which power HMIs.
Before we begin, it’s important to note that there’s no universal standard for creating an HMI. On the contrary, many companies have their own definitions regarding what exactly is an HMI. As such, different HMIs may feature different components. With that said, most HMIs share some basic components.
One of the most common components found in HMIs is a membrane switch. Switches, as you may already know, are used to toggle on and off an electrical circuit. When the switch is “on,” it completes the circuit; thus, allowing the device or component to function. When the switch is “off,” the circuit is closed. A membrane switch performs these operations with the use of a membrane-like design. Membrane switches are resistant to moisture and debris, making them an excellent choice when used in the construction of an HMI.
In addition to membrane switches, many HMIs also feature rubber keypads. Keypads are made using many different materials, including plastic and rubber. The latter, rubber, is unique in the sense that it provides a combination of light tactile feedback, water and dust resistance properties, and improved ergonomics. Rubber keypads are also less prone to breakage when compared to its plastic counterpart. Generally speaking, you can expect rubber keypads to last longer than plastic keypads, which is just one more reason why they are frequently used in HMIs.
A third component that’s commonly used in HMIs is a touchscreen interface. Touchscreen interfaces typically use either resistive or capacitive technology to identify the operator’s touch. With capacitive technology, the electrical charge created by the operator’s hand is transferred to the HMI, at which point the HMI uses this information to calculate the point of touch. Resistive touchscreens differ in the sense that they use pressure, not electrical charges, to identify touch.
Did this give you a better understanding of the different components used in human machine interfaces?