What does Light Pen Mean?
A light pen is a light-sensitive computer input device, basically a stylus, that is used to select text, draw pictures and interact with user interface elements on a computer screen or monitor. The light pen works well with CRT monitors because of the way such monitors scan the screen, which is one pixel at a time, giving the computer a way to keep track of the expected scanning time by the electron beam and infer the pen's position based on the latest timestamp of the scanning.
Light Pen Explains?
The light pen can be considered as the predecessor to touchscreen technology and was first created in 1995 as part of the Massachusetts Institutes of Technology's (MIT) Whirlwind Project, a Cold War vacuum tube military computer. The pen allowed users to precisely select individual pixels on the screen and to draw and interact with menu elements in much the same way as users interact with touchscreen displays. The light pen became common in the 1960s on graphics terminals such as the IBM 2250 and was also available for text-only terminals. It also became popular during the 1980s for home computers such as the Atari and Commodore 8-bit computers. However, the concept of operation of the light pen is not compatible with modern LCD screens and, as a result, the input device eventually died out.
The light pen works by detecting the change in brightness of nearby pixels. which indicates that the CRT's electron beam is scanning in that area; it then sends the timing of this event to the computer, which then compares this information to the timestamp of the last scan by the electron beam, allowing the computer to infer the precise location of the pen.
Light Pen Uses :
- Light pens can be used as input coordinate positions by providing necessary arrangements.
- If background color or intensity, a light pen can be used as a locator.
- It is used as a standard pick device with many graphics systems.
- It can be used as stroke input devices.
- It can be used as valuators.
Digitizers :
The digitizers is an operator input device, which contains a large, smooth board (the appearance is similar to the mechanical drawing board) & an electronic tracking device, which can be changed over the surface to follow existing lines. The electronic tracking device contains a switch for the user to record the desire X & Y coordinate positions. The coordinates can be entered into the computer memory or stored or an off-line storage medium such as magnetic tape.
Advantages :
1. Drawing can easily be changed.
2. It provides the capability of interactive graphics.
Disadvantages :
1. Costly
2. Suitable only for applications which required high-resolution graphics.
A Light Pen may refer to any of the following :
1. A light pen is a light-sensitive pointing input device commonly used to select or otherwise modify text or data on a screen. Used with a CRT monitor, these devices were an early form of manipulating and highlighting data on the screen. In the picture, is an example of a woman using a light pen to highlight text on the screen.
Light pens were originally developed around 1955 and in the 1960s, they became more commonly used with graphics terminals, like the IBM 2250. In the 1980s, light pen usage expanded to home computers, like the BBC Micro computer. Some graphics cards also include a connection for a light pen.
Today, light pens are no longer used due to the invention of touch screens.
2. The term light pen may also refer to a pointing input device utilizing a light that is commonly used during a presentation. The light pen is a very focused flashlight-type of device or a laser pointer. It may be used to direct viewers' attention to a specific area, such as a picture or text in a presentation.
3. A light pen may also be used to describe the pen (sylus) used with a graphics tablet.
Writer: Mr. Krishan Kumar Saini
Today we have learnt Basics about Light Pen. Hope this lesson is helpful for you.
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