Keypads are a fundamental component used in a variety of human machine interfaces (HMIs). Some people assume that all keypads are the same, but this isn’t necessarily true. The two most common types of keypads are membrane and mechanical. We’ve talked about membrane keypads before on our blog, so today we’re going to discuss the latter. While the underlying principle behind them remains the same — to support input from the operator- – there are other subtle differences that shouldn’t go unnoticed. And we’re going to explore these differences in today’s blog post.
Mechanical keypads are characterized by the use of individual, separate keys. This is in stark contrast to membrane keypads, in which the keys are all embedded together. In a traditional, standard mechanical keypad, the key cap sits atop a plunger that depresses when pressed. Pressing down on a mechanical key causes this key to make contact with the plunger; thus, the electrical circuit is created and the respective keypress is registered by the device. It’s a relatively simple mechanism that works surprisingly well.
It’s important to note that most mechanical keypads register the keypress before the key comes into contact with the plunger. For instance, it’s not uncommon for a mechanical keypad to register the kepress about halfway through this process, meaning you don’t have to press down the key completely in order for your keypress to register.
There are several benefits associated with the use of mechanical keypads, one of which is the presence of tactile feedback. Tactile feedback refers to any mechanism that informs the operator that his or her touch was registered. Pressing down on a mechanical keypad typically produces a light vibration-like feeling from the plunger attempting to return to its default position, which lets the operator know that his or her keypress was registered. While membrane keypads may also support the use of tactile feedback, it’s typically less than that of a mechanical keypad.
On the other hand, however, mechanical keypads are more prone to failure than membrane keypads. If dirt, debris and/or moisture becomes embedded underneath the keys, it may prevent the electrical circuit from being completed when the key is pressed; thus, rendering the keypad ineffective. Business owners who are looking for a new keypad to use outdoors or in other high-stress environments should probably stick with a membrane keypad for this very reason.
Hopefully, this will give you a better understanding of mechanical keypads and how they work.