INPUT DEVICE
In computing,
an input device is any peripheral (piece
of computer hardware equipment) used to
provide data and control signals to aninformation processing system such as
a computer or
other information appliance. Examples of input
devices include keyboards, mice,scanners, digital cameras and joysticks.
Many input
devices can be classified according to:
·
modality of input (e.g. mechanical
motion, audio, visual, etc.)
·
the input is discrete (e.g. key
presses) or continuous (e.g. a mouse's position, though digitized into a
discrete quantity, is fast enough to be considered continuous)
·
the number of degrees of freedom
involved (e.g. two-dimensional traditional mice, or three-dimensional
navigators designed for CADapplications)
Pointing
devices, which are input devices used to specify a position in space, can
further be classified according to:
·
Whether the input is direct or
indirect. With direct input, the input space coincides with the display space,
i.e. pointing is done in the space where visual feedback or the pointer appears. Touchscreens and light pens involve
direct input. Examples involving indirect input include the mouse and trackball.
·
Whether the positional information is
absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be
lifted and repositioned)
Direct input
is almost necessarily absolute, but indirect input may be either absolute or
relative.[clarification needed] For
example, digitizing graphics tablets that do not have an
embedded screen involve indirect input and sense absolute positions and are
often run in an absolute input mode, but they may also be set up to simulate a
relative input mode like that of a touchpad,
where the stylus or puck can be lifted and repositioned.
Input and output devices make
up the hardware interface between a computer and a scanner or 6DOF controller.
Following are few of the important input devices which are used in
Computer Systems
·
Keyboard
·
Mouse
·
Joy Stick
·
Light pen
·
Track Ball
·
Scanner
·
Graphic Tablet
·
Microphone
·
Magnetic Ink Card Reader(MICR)
·
Optical Character Reader(OCR)
·
Bar Code Reader
·
Optical Mark Reader
Keyboard
Most common and very popular input device is keyboard. The keyboard
helps in inputting the data to the computer.The layout of the keyboard is like
that of traditional typewriter, although there are some additional keys
provided for performing some additional functions.
Keyboard are of two sizes 84 keys or 101/102 keys, but now 104 keys or
108 keys keyboard is also available for Windows and Internet.
The keys are following
Sr. No.
|
Keys
|
Description
|
1
|
Typing Keys
|
These keys include the letter keys (A-Z) and digits keys (0-9) which
are generally give same layout as that of typewriters.
|
2
|
Numeric Keypad
|
It is used to enter numeric data or cursor movement. Generally, it
consists of a set of 17 keys that are laid out in the same configuration used
by most adding machine and calculators.
|
3
|
Function Keys
|
The twelve functions keys are present on the keyboard. These are
arranged in a row along the top of the keyboard.Each function key has unique
meaning and is used for some specific purpose.
|
4
|
Control keys
|
These keys provides cursor and screen control. It includes four
directional arrow key.Control keys also include Home, End,Insert, Delete,
Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).
|
5
|
Special Purpose Keys
|
Keyboard also contains some special purpose keys such as Enter, Shift,
Caps Lock, Num Lock, Space bar, Tab, and Print Screen.
|
Mouse
Mouse is most popular Pointing device. It is a very famous
cursor-control device. It is a small palm size box with a round ball at its
base which senses the movement of mouse and sends corresponding signals to CPU
on pressing the buttons.
Generally it has two buttons called left and right button and scroll bar
is present at the mid. Mouse can be used to control the position of cursor on
screen, but it cannot be used to enter text into the computer.
ADVANTAGES
·
Easy to use
·
Not very expensive
·
Moves the cursor faster than the arrow
keys of keyboard.
Joystick
Joystick is also a pointing device which is used to move cursor position
on a monitor screen. It is a stick having a spherical ball at its both lower
and upper ends. The lower spherical ball moves in a socket.TheJoystic can be
moved in all four directions.
The function of joystic is similar to that of a mouse. It is mainly used
in Computer Aided Designing(CAD) and playing computer games.
Light Pen
Light pen is a pointing device which is similar to a pen. It is used to
select a displayed menu item or draw pictures on the monitor screen.It consists
of a photocell and an optical system placed in a small tube.
When light pen's tip is moved over the monitor screen and pen button is
pressed, its photocell sensing element detects the screen location and sends
the corresponding signal to the CPU.
Track Ball
Track ball is an input device that is mostly used in notebook or laptop
computer, instead of a mouse. This is a ball which is half inserted and by
moving fingers on ball, pointer can be moved.
Since the whole device is not moved, a track ball requires less space
than a mouse. A track ball comes in various shapes like a ball, a button and a
square.
Scanner
Scanner is an input device which works more like a photocopy machine. It
is used when some information is available on a paper and it is to be
transferred to the hard disc of the computer for further manipulation.
Scanner captures images from the source which are then converted into
the digital form that can be stored on the disc.These images can be edited
before they are printed.
Digitizer
Digitizer is an input device which converts analog information into a
digital form. Digitizer can convert a signal from the television camera into a
series of numbers that could be stored in a computer. They can be used by the
computer to create a picture of whatever the camera had been pointed at.
Digitizer is also known as Tablet or Graphics Tablet because it converts
graphics and pictorial data into binary inputs. A graphic tablet as digitizer
is used for doing fine works of drawing and images manipulation applications.
Microphone
Microphone is an input device to input sound that is then stored in
digital form. The microphone is used for various applications like adding sound
to a multimedia presentation or for mixing music.
Magnetic Ink Card Reader(MICR)
MICR input device is generally used in banks because of a large number
of cheques to be processed every day. The bank's code number and cheque number
are printed on the cheques with a special type of ink that contains particles
of magnetic material that are machine readable.
This reading process is called Magnetic Ink Character Recognition(MICR).
The main advantages of MICR is that it is fast and less error prone.
Optical Character Reader(OCR)
OCR is an input device used to read a printed text. OCR scans text
optically character by character, converts them into a machine readable code
and stores the text on the system memory.
Bar Code Readers
Bar Code Reader is a device used for reading bar coded data (data in
form of light and dark lines). Bar coded data is generally used in labelling
goods, numbering the books etc. It may be a hand held scanner or may be
embedded in a stationary scanner.
Bar Code Reader scans a bar code image, converts it into an alphanumeric
value which is then fed to the computer to which bar code reader is connected.
Optical Mark Reader(OMR)
OMR is a special type of optical scanner used to recognize the type of
mark made by pen or pencil. It is used where one out of a few alternatives is
to be selected and marked. It is specially used for checking the answer sheets
of examinations having multiple choice questions.