Abstract: A switch for use in a keyboard consists of an input light pipe, one or more output light pipes and means selectively operable to cause light to be reflected from the input light pipe into the output light pipes. The output light pipes are preferably connected to photodetectors which detect whether or not the switch is actuated by determining the amount of light incident thereon. When such a switch is to be used in a keyboard which is required to produce a coded output, one photodetector is provided for each digit of the code and output light pipes on the various switches are connected to the photodetectors in accordance with the code.