Keypads are used in countless applications, ranging from handheld calculators and TV remote controls to human machine interfaces (HMIs), elevator buttons and more. But even if you’re familiar with their general design, there are probably some things you don’t know about keypads and how they work.

#1) Available in a Variety of Materials

Plastic is the most common material in which keypads are made. However, it’s not the only material in their construction. While most keypads are made of plastic, some are made of alternative materials like silicone rubber. These rubber silicone keypads boast a uniquely soft and supple texture that many people prefer.

#2) Mechanical and Membrane Switch Technology

All keypads feature an electrical switch, with mechanical and membrane switches being the most common. A mechanical switch, of course, uses copper and plastic parts to mechanically control the circuit, whereas a membrane switch uses the conductive properties of copper, silver or graphite ink to control the circuit.

#3) Some Keypads Have Backlighting

You may discover that some keypads have backlighting. Just like TVs, computer monitors and other display devices, these keypads are characterized by an internal light source that illuminates the front of the keypad. The most common types of backlighting used in keypads include light-emitting diode (LED), optical fiber and electroluminescent (EL). Of those three options, LED offers the highest level of energy efficiency. LED-backlit keypads last longer while consuming less energy than both optical fiber- and EL-backlit keypads.

#4) The Numerical Layout Was Published in 1960

According to Wikipedia, the numerical layout that’s now used in nearly every keypad was published by Bell Labs in 1960. Specifically, the company published a study called “Human Factor Engineering Studies of the Design and Use of Pushbutton Telephone Sets,” which cited the benefits of using the layout.

#5) Keypads Consisting Mostly of Numbers Are Called Numerical Keypads

Not all keypads contain letters; some consist entirely or mostly of numbers. These keypads are called numerical keypads because of their emphasis on numbers. Numerical keypads are simple, easy to use and familiar to most users, making them a popular choice in certain applications.

#6) Keypads Containing Letters and Numbers Are Called Alphanumeric Keypads

There are also keypads that contain both letters and numbers. Known as alphanumeric keypads, they tend to be larger than their numeric counterparts, requiring a larger surface area to accommodate for the additional letters. Alphanumeric keypads are frequently found on point of sale (POS) systems, HMIs and more.