Hey guys, after a lot of theory lets hop on to some technical advancements...
U can see a light pen in the above pic. wanna know about light pen????
given below are the details of this pen!!!
- Light Pen, a pointing device in which the user holds a wand, which is attached to the computer, up to the screen and selects items or chooses commands on the screen either by pressing a clip on the side of the light pen or by pressing the light pen against the surface of the screen.
- The wand contains light sensors and sends a signal to the computer whenever it records a light, as during close contact with the screen when the non-black pixels beneath the wand's tip are refreshed by the display's electron beam.
- The computer's screen is not all lit at once—the electron beam that lights pixels on the screen traces across the screen row by row, all in the space of 1/50 of a second.its hard to imagine.. right???
- By noting exactly when the light pen detected the electron beam passing its tip, the computer can determine the light pen's location on the screen.
- The light pen doesn't require a special screen or screen coating, as does a touch screen, but its disadvantage is that holding the pen up for an extended length of time is tiring to the user.
- Light pens are often used in computer-aided design and computer-aided manufacture (CAD and CAM) technology because of the flexibility they provide.
what a wonderful invention.. isn't it??????
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