2. Input – Output Devices
• Also known as Peripheral Devices.
• These surround a computer’s CPU and
3. Input Devices
• An Input Device is an electromechanical
device that accepts data from outside
world and translates them into a form a
computer can interpret.
• It a hardware device that sends data to a
6. • A 'keyboard' is a human interface device
which is represented as a layout of
• Keyboards allow a computer user to input
letters, numbers, and other symbols into a
• Keyboards are also used for computer
11. • A trackball is a pointing device consisting
of a ball held by a socket.
• The socket contains sensors to detect a
rotation of the ball about two axes.
• The user rolls the ball to direct the cursor
to the desired place on the screen and can
click one of two buttons near the trackball
to select objects on the screen.
12. TOUCH SCREEN
• A display device that allows a user to
interact with a computer by touching areas
on the screen.
13. • These are used in
ATM, Tablets, Smartphones, and other
15. LIGHT PEN
• A light pen is a pen-shaped input device.
• A light pen utilizes a light sensitive
detector, requiring you to hold a pen and
point it at the screen.
• The device contains a light sensor
which, when pointed at a cathode ray tube
screen, generates a signal each time the
electron beam raster passes by the spot
the pen is pointing at.
16. • Light enters the lens of a light pen, where
it encounters a photoelectric cell, which
converts the energy to a signal that is sent
to the computer. The light is obtained from
the refresh of the CRT, and at the instant
the light is generated, the computer knows
what location on the screen is being
refreshed; this information is coordinated
with the signal from the light pen, and is
subsequently used by the graphics
software to make a decision.
• Also known as a digitizer or graphics
• A digitizer tablet is an input device used to
convert hand-drawn images into a format
suitable for computer processing.
• Images are usually drawn onto a flat
surface with a stylus and then appear on a
computer monitor or screen.
20. • The device consists of a flat surface upon
which the user may "draw" or trace an
image using an attached stylus.
• The image is displayed on the computer
• Used for technical drawing, CAD, graphics
editing program, etc.
21. Imaging And Video Input Devices
• Digital Camera
• Fingerprint Scanner
• Image Scanner
• Optical Recognition Devices --
OMR, OBR, OCR
• A scanner is an input device used to
capture information, such as, photographs
and documents on paper and translate the
information into a computer image.
• It is a device that optically scans
images, printed text, handwriting, or an
object, and converts it to a digital image.
• Most scanners have a flat scanning surface.
24. • OMR: OMR which stands for Optical Mark Recognition
is the process of gathering data with an optical scanner
by measuring the reflectively of light at predetermined
positions on a surface.
OCR: OCR stands for Optical Character Recognition.
OCR is the recognition of printed or written text
characters by a computer. It is the application software
that allows a computer to recognize printed or written
characters, e.g. letters, numbers, punctuation
marks, and pictograms using an optical scanner for
input. OCR is being used by libraries to digitize and
preserve their holdings.
OBR: It stands for Optical Bar Code Reader which is
used for reading bar-coded data. It scans a set of vertical
bars of different width for specific data and is used to
read tags. Bar code reading is done by a light pen or
scanner connected to a computer.
25. BAR CODE READER
• Bar code readers are used very
extensively in supermarkets. Look closely
at a packet of biscuits. Do you see a set of
narrow ad broad lines printed on the
wrapper? This is a bar code. Bar codes
contain all the information about an
item, such as price and weight. When this
bar code reader is shown over a bar code
reader, the information about the item is
automatically sent to the computer. Then