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A light pen can refer to a pen with an LED lamp, a pen for long exposure photography, a tablet pen, or an input device for a computer display. The prototype was made by the Whirlwind Project at MIT and works by selecting dots on a CRT screen. While lightweight pens were popular in the 1980s, ergonomic strain limited their use. They are still used in industries such as retail sales, gaming, and healthcare, with new innovations including barcode scanners.
The term light pen has several meanings. First, it refers to a battery-operated lighted pen that has an LED lamp in the tip to allow you to write in the dark. Secondly, it refers to pens used to create light “scribbles” for long exposure photography. Third, it is used by some to refer to a tablet pen for interacting with a computer via a peripheral tablet, whether or not light is actually used in the operation of the tablet pen. Fourth, and most frequently, it is an input device that allows a user to interact with a computer display.
The prototype of the light pen was made by the Whirlwind Project at the Massachusetts Institute of Technology (MIT). Whirlwind was a 1950s prototype computer for the United States Air Defense System, and the light pen – shaped like a gun with a handle attached under the barrel of the pen – was used to select dots on the CRT screen (tube cathode) of that system.
The light pen works like a receptor that works in connection with a computer display. The button on the pen is pressed when it contacts a dot on the display. Then, when the pixel that the pen is marking updates, the flash of light identifies the position, transmitting information related to that position, identifying the x and y coordinates. The pen can be used to select items on the display or to draw on the display. The opportunity to be able to interact “naturally” as one does with a pencil or pen, rather than a keyboard or mouse, was seen as a great advance.
Lightweight pens enjoyed 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 in use on the Jeopardy TV show as a tool for contestants to write their bets, as well as in some industries. The arenas where the pen continues to be used include retail sales in POS applications, kiosks, gaming, graphic arts and healthcare applications. New innovations in light pens include models that combine technology with a barcode scanner.
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