The term light pen has several meanings. Firstly, it refers to a battery-powered illuminated pen that has an LED lamp at the tip to enable writing in the dark. Second, it refers to pens used to create light “squiggles” for long-exposure photography. Third, it is used by some to refer to an electronic pen for interacting with a computer through a peripheral graphics tablet, regardless of whether or not light is used in the operation of the electronic pen. Fourth, and most often, it is an input device that allows the user to interact with the computer screen.
A light pen can refer to a battery-operated illuminated pen that has an LED bulb at the tip.
The prototype of the light pen was made by the Whirlwind Project of the Massachusetts Institute of Technology (MIT). Whirlwind was a prototype computer from the 1950s for the United States air defense system, and the stylus, in the form of a pistol with a cable attached below the barrel of the stylus, was used to select points on the CRT screen. (tube lightning) as part of that system.
Some people refer to tablet pens as light pens.
The optical pen works as a receiver that works in connection with a computer monitor. The pen button is pressed by making contact with a point on the screen. Then, when the pixel the pen is marking is updated, the burst of light identifies the location, transmitting information connected to that location, identifying the x and y coordinates. The pen can be used to select items on the screen or draw on the screen. The opportunity to interact “naturally” as one does with a pencil or pen, rather than a keyboard or mouse, was considered a breakthrough.
Light pens had a heyday in the early 1980s, but the ergonomic strain of holding the pen to a screen over time limited their use. However, they are still used on the television show Jeopardy as the tool with which competitors write their bets, as well as in some industries. Areas where the pen continues to be used include retail point-of-sale (POS) applications, kiosks, gaming, graphic arts, and healthcare applications. Innovations in lightweight pens include models that combine the technology with a barcode reader.
