light pen
Noun: A light pen is a handheld input device used with a computer display. It functions as a pointer by detecting light emitted from the screen. When the tip of the pen is pointed at a specific spot on the display, it senses whether that spot is illuminated, allowing the user to select, draw, or interact directly with the screen.
The light pen is used to interact directly with a cathode-ray tube (CRT) computer monitor. The user points the pen at the desired location on the screen. * The graphic designer used a light pen to draw directly on the monitor. * Early computer-aided design (CAD) systems often relied on a light pen for input.
While largely obsolete for modern displays, the light pen was a precursor to modern touch-screen and stylus technology. Its operation was dependent on the specific scanning technology of CRT monitors. * The light pen could only function correctly with a compatible CRT display due to its method of sensing the electron beam's illumination.
- Stylus: A pen-like tool used for input on touch-sensitive screens, but it does not sense light; it interacts via pressure or electrical conductivity.
- Touchscreen: A display that detects touch input directly, eliminating the need for a separate pointing device like a light pen.
- Electronic pen
- Light gun (a related device used for targeting on screens, often in gaming)
- Pointer: A general term for any device, like a mouse or pen, used to point to locations on a screen.
- Input device: A broader category including light pens, mice, keyboards, and touchpads.
- (computer science) a pointer that when pointed at a computer display senses whether or not the spot is illuminated