There are two different devices that can be referred to as infrared (IR) keyboards. One type of IR keyboard is similar in design and function to a traditional keyboard, though infrared light is used to transmit data to a computer rather than a hardwired connection. These keyboards can be used with desktop personal computers (PCs), laptops and even personal digital assistants (PDAs). The other type of IR keyboard uses a visible laser to project a virtual keyboard over a flat surface. An invisible infrared sensor beam then tracks movement over that surface and translates it into keypunches.
Infrared is a type of invisible light that can be pulsed or modulated for use in data transfer. It is typically less expensive than other wireless methods, but has range and line of sight limitations. An IR keyboard that makes use of this technology to communicate with a computer typically needs to be within about 30 feet (9 meters) of the receiver, though many devices are less powerful. It is sometimes possible to use a mirror or another extension device to get around the line of sight limitation, though this is often not an issue when using an IR keyboard under normal circumstances.
Some computers come equipped with infrared sensor ports, though it is not a common option. In order to use a keyboard that communicates over an IR connection, some type of receiver peripheral is typically needed. These receivers often connect via universal serial bus (USB), and some are designed specifically to pair with a certain IR keyboard or keyboard and mouse combination.
IR keyboards that are designed for use with PDAs, smartphones and other similar devices are often collapsible or can be folded up for easy transport. Instead of a simple IR transmitter, this type of keyboard typically has a cradle or a swing arm. The cradle or swing arm is designed to hold a PDA or smartphone so that the IR sensor on the device will line up with the IR transmitter on the keyboard. Some of these can also adjust to allow either a portrait or landscape orientation for the PDA or smartphone.
The other type of keyboard that makes use of infrared light is typically known as a projection keyboard. These devices use visible laser light to project a keyboard image across a flat surface. This space is also bathed in invisible infrared light, which is able to measure the movement of a typist's fingers over the keys. This motion is translated into keypunches and sent to a computer just like the inputs from a regular keyboard.