The document discusses the light pen, a pointing device shaped like a pen that contains light sensors and connects to a visual display unit. The tip of the light pen detects light from the screen to identify its location. It works by sensing changes in brightness when the electron gun refreshes spots on the screen. The light pen allows users to touch the screen to activate commands and selections with great position accuracy, similar to a touchscreen. While it provides accuracy and precision for selections and drawing directly on the screen, disadvantages include the inability to erase and fatigue from extended use.

1. A presentation on
Light Pen
By- Vinisha Pathak

2. What is Light Pen ?What is Light Pen ?
A Light Pen is a
pointing device
shaped like a pen
which contains light
sensors and is
connected to a VDU
(Visual Display Unit).

3. The tip of the light pen
contains a light-
sensitive element which,
when placed against the
screen, detects the
light coming from the
screen, enabling the
computer to identify the
location of the pen on
the screen.

4. How does it work ?How does it work ?
A light pen is fairly simple to
implement.
The light pen works by sensing the
sudden small change in bright-
ness of a point on the
screen when the electron gun
refreshes that spot.

5. 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 its side.
A signal is sent to the computer, which
then works to display light pen’s exact
location on the screen.

6. The light pen system
allows the user to
touch the computer screen
with a lighted pen to
activate commands and
make selections.
It also allows the user to
point to displayed
objects, or draw on the
screen, in a similar way to
a touch screen with
great position accuracy.

7. Its AdvantagesIts Advantages
Allows you to select object on
a display screen.
It has great accuracy and is
more precise.
It does’nt 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 !!

8. Its DisadvantagesIts Disadvantages
One of the main disadvantages is that
you cannot erase a pen. Once you've
written something with pen, it stays there.
Pen can obscure display, is fragile, can
be lost on a busy desk, tiring on the
arm.
Are less popular as compared to the
mouse !!

9. The endThe end
Any Question ??Any Question ??

10. ThankyouThankyou
Made by-Made by-
Vinisha PathakVinisha Pathak