Light pen Technology

This document discusses light pen technology. It provides a brief history of the light pen, noting it was invented in 1955 and commonly used with graphics terminals in the 1960s. The document explains that a light pen contains light sensors and works by sensing changes in brightness on a CRT screen when the electron gun refreshes spots. When pressed against the screen, a light pen sends a signal to the computer with its location. Advantages of a light pen include precision, ability to select objects and draw directly on screen. The document contrasts light pens with styli, noting styli are smaller and require only screen pressure while light pens require a computer connection and can perform additional functions like note taking.