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.

1. LIGHT PEN
TECHNOLOGY

2. Contents:-
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Topic
Introduction
History
The present
Mouse and Light Pen
How does it work?
Advantages
Stylus and Light Pen
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3. Introduction
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• A light pen is a pencil-shaped input device
that are used in conjunction with CRT (
Cathode Ray Tube) displays.
• It allows the user to point to displayed
objects or draw on the screen in a similar
way to a touchscreen but with greater
positional accuracy.
• It contains light sensors and is connected to
a VDU ( Visual Display Unit).

4. History
◇ The light pen was invented by Ben Gurley.
◇ The first light pen was created around 1955 as part of
the Whirlwind project at MIT.
◇ During the 1960s light pens were common on graphics
terminals such as the IBM 2250, and were also
available for the IBM 3270 text only terminal.
◇ Light pen usage was expanded in the early 1980s to
music workstations.
◇ Later, Sanyo produced a light pen interface cartridge.
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5. The present
Now-a-days, the light
pen has come in handy
for laptop users.
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6. Mouse is a most popular pointing device. It is a
cursor control device having a small palm size box
with a round ball at the base which sense the
movement of the mouse and sends corresponding
signals to CPU when the mouse button are pressed
whereas a Light Pen is a pointing device which is
similar to a mouse which is just like a writing pen with
a pointing ball in it’s tip.
Mouse and Light Pen
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7. How does it work?
 A light pen is fairly simple to implement.
 The light pen works by sensing the sudden small
change in brightness of a point on the screen
when the electron gun refreshes that spot.
 It is used to choose objects or commands on the
screen either by pressing it against the surface
of the screen or by pressing a small switch on
it’s side.
 A signal is sent to the computer, which then
works to display light pen’s exact location on the
screen.
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8. It’s advantages:
 Allows to select object on a display
screen.
 It has great accuracy and is more
precise.
 It doesn’t need a special screen or a
screen coating.
 It can be used for fine selections and
drawing.
 It draws directly on the screen so that it is
more accurate.
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9. Stylus and Light pen
Due to an inherent difference in intended function, the
stylus differs greatly from the digital pen. Both are utilized
to input information into a display device , but their role in
doing varies.
 Stylus : A stylus is primarily used to input and
manipulate information on a PDA device. Small
and thin, these pens allow users to tap through
menus, write notes and draw on their device.
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 Digital Pens: Used in conjunction with a computer,
digital pens allow for a much broader range of
function than a stylus. Graphic designers often use
digital pens to create art on tablet PCs while avid
students take full-blown notes in class. These
devices translate motion back to the computer,
where it is rendered into graphics, writing or text.

11.  Other differences: A stylus is generally smaller
and much thinner than a digital pen because it
contains no internal electronics. Many digital
pens do more than just write or draw. While
stylus requires only pressure on the screen of a
PDA for it’s input to be recorded whereas digital
pens require some form of connection to a
computer to operate, whether a form of a wire,
Bluetooth connection etc. Many digital pens
also require the use of special types of paper
whereas a stylus needs only the screen of it’s
parent device.
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12. Thank
You All!
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13. Credits
Special thanks to all the people who made and released
these awesome resources for free:
◇ Presentation template by SlidesCarnival
◇ Photographs by Unsplash
◇ Information from the internet.
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