Silicone-rubber keypads have become increasingly popular in recent years. Characterized by the use of silicone-rubber materials, they create an angled webbing-like texture around the center of each switch. When the operator presses down on a button, it causes the webbing to deform; thus, producing a tactile response. And when the operator releases his or her finger, the webbing returns to its default state, complete with positive feedback. Today, we’re going to take a closer look at silicone-rubber keypads, revealing some important terms associated with this technology.
Snap Ratio — the term “snap ratio” is often used in conjunction with silicone-rubber keypads. So, what does this term mean? Snap ratio is essentially a measurement of tactile feedback felt by the operator. According to Wikipedia, the recommended snap ratio for silicone-rubber keypads is between 40 and 60%. Using a silicone-rubber keypad with a snap ratio of lower than 40% will reduce in a loss of tactile feedback. On the plus side, however, lower snap ratio are associated with longer lifespan, meaning the keypad will last longer.
Tactile Feedback — now that you know the definition of snap ratio, you might be wondering what is tactile feedback. Even if you are unfamiliar with the term, you’ve probably experienced tactile feedback before. Tactile feedback is the “feeling” produced by a device as a response to input. When you tap a key on your smartphone, for instance, it usually responds by producing a light vibration, which is a common type of tactile feedback used in touchscreen devices.
International Protection Marking — you’ll also notice that many silicone-rubber keypads are labeled with an International Protection Marking (IPM). Often referred to an Ingress Protection Marking, this label indicates the keypad’s ability to withstand the intrusion of dust, moisture and other elements. Long story short, a silicone-keypad with a high IPM will function more effectively in “dirty” and moist environments than a similar keypad with a low IPM.
Laser Etching — many silicone-rubber keypads are made with laser etching technology. As the name suggests, laser etching involves the use of high-powered laser to selectively remove portions of the paint covering the top layer of the keys. In turn, this reveals a lighter color of paint from underneath the newly removed top portion; thus, producing an enhanced backlight.
Human Machine Interface — silicone-rubber keypads are often used with human machine interfaces (HMIs). Not to be confused with a graphical user interface (GUI), HMIs offer an interface through a human operator controls a machine.