1) Keyboards are the most common method of entering text into computers. They use electronic switches under each key and come in standard and ergonomic designs. 2) Mice allow users to control the on-screen cursor with hand movements. Standard mice use rollers or optics to detect movement and buttons to click. Alternatives like trackballs and touchpads reduce strain. 3) Graphics tablets enable natural drawing input but are best for artwork not menu navigation. Their styluses can detect pressure to vary line thickness.

1. INTERACTIVE
INPUT DEVICES

2. Keyboard
• Common method of entering data
• Often called the QWERTY keyboard
• Consists of a rows of electronic
switches encased in a plastic
surround, which has a graphic that
describes its function
• Key stokes are combined to modify
the input

3. Keyboard
Advantage:
• The most efficient way of entering
numbers, text and commands into the
computer, as each key has a specific
function.
• Inexpensive, as virtually every
computer needs one.

4. Keyboard
Disadvantage:
• You have to learn to type!
• There are 'arrow keys' but they are
not as good as a mouse for controlling
the screen cursor.
• May cause sore wrists and arms

5. Alternative Keyboards
• Designed to reduce repetitive strain
• Hands fit in the molding and wrist
need not have to move so much
• Use key combinations to type letters
and characters
• Another type – more comfortable
than the standard one

6. Keyboard for physical
disabilities
• Keyguard – plate fits over the
keyboard with holes positioned over
the keys
• Keyguard – steel with wipe clean
surface and held in place with dual
lock
• People with disabilities rest their
hands on the keyguard – prevents
accidental keystrokes

7. Mouse
• Popular way of controlling the screen
cursor through the use of on-screen
‘menus’
• Fits within the palm of your hand
• Detects the back and forth
movement and input the X-Y (left-
right,forward-backward) data into
the computer

8. • Switches – depressed to cause ‘click’
data to be input, ‘clicks’ control
screen menus
• Some have little wheel – to scroll
within windows
• Wireless mouse – use radio signals
rather than wires to connect to
computer
• Two mechanisms to detect hand
movements
 ‘Roller ball’
 ‘Optical’ mouse

9. Advantages:
• One of the easiest way of
translating. X-Y hand movements into
the computer.
• Excellent for controlling the cursor,
menus and windows on screen.
• Easy to use.

10. Disadvantage:
• You have to have space next to the
keyboard to move the mouse.
• Prolonged use can give you sore
wrists and arms.
• Not as good as a graphics tablet for
drawing straight lines and shapes on
screen

11. Alternatives
‘Trackball Mouse’
 reduce wrist movements, thus
reduce repetitive strain
 rolling the ball controls the
cursor
 switches – work in same way as
standard mouse

12. Alternatives
‘Whale Mouse’
• Contoured palm rest encourages neutral
wrist, hand and finger positions.
• Promotes the use of the larger arm
muscles relaxing the more delicate
muscles
• Minimizes sharp, quick wrist movements
that can lead to injury.
• Easily adjusts to fit any size hand - left
or right.

13. Graphics Tablet
• Excellent device for use with drawing
or graphics package
• Using pen – natural method of
drawing lines and shapes
• Allows X-Y data input same as mouse
• Slide the stylus along the surface
which inputs the movement to the
computer

14. • Natural hand and arm movement than
mouse for creating sweeping lines and
curves
• Can create thick and thin lines –by
pressing harder or lighter on the
stylus

15. Advantage:
• Excellent for use with a drawing or
graphics package to draw lines and
shapes.
• Can input pressure data for use in a
graphics package

16. Disadvantage:
• More expensive than a mouse,
especially in the larger sizes.
• Not as precise as a mouse for menu
control, so it tends to be an addition
rather than a replacement- you can
run both perfectly well by making
sure the pen is off the tablet when
you do not need it.

17. Concept Tablet
• Touch sensitive
• Plastic sheet with various pictures
and graphics is placed on the surface
• Tapping the picture cause a command
to input
• Appropriate software is used to
sense these commands

18. Advantages:
• Can be used to issue specific
commands to the computer.
• Avoids staff having to know the price
of everything.
• Allows software to be controlled with
a single touch of the tablet.

19. Disadvantage:
• There has to be the right software
running for the command to make
sense.
• Number of commands that can be
issued is limited by the size of the
device.

20. Touch Screen
Uses:
• Dusty, dirty or wet environments
where a keyboard would be damaged
• Hazardous environments where there
must not be any chance of a spark
• Constricted areas where there is no
room for another input device
• Hygienic environments where it must
be simple to wipe clean

21. • Optical touch screen
 LEDs along one vertical and
horizontal edge and detectors on the
other
• Electrical touch panel
 Two transparent plates one
coated with conductive material and
other resistive material separated by
distance

22. • Acoustic touch panel
 high frequency sound waves
generated in horizontal and vertical
directions across a glass plate
 touching the screen reflects
the wave from fingers to emitters
 time interval between
transmission and reflection gives the
position of contact

23. Advantage:
• No moving parts
• Can use any number of menu levels
• Can display large text to assist less-
sighted people

24. Disadvantages:
• Expensive compared to a standard
keyboard or mouse.
• Has to have specific software to
make sense of the input.
• Can be a problem seeing the screen in
bright sunlight.

25. Scanner
• Input graphic information
• Input picture is laid flat, face down on
the scanner surface with lid lowered
to avoid stray light creeping in
• Sensor sweeps along the picture –
image is built up as a series of ‘pixels’

26. • A scanner can
1) Create a black and white image -
handy for line drawings and text
2) Create a full color image - excellent
for inputting photographs
• Low resolution, black and white image
 small file size with a few hundred
kilobytes at most
• High quality, high resolution image 
huge file size with several megabytes

27. Advantage:
• Scanners can convert photographs
and flat documents into electronic
images.
• Both color and black & white images
can be created.
• Extremely high resolution if required.
• Relatively inexpensive compared to a
digital camera.

28. Disadvantages:
• Cannot take 3 dimensional images.
• Document has to fit on the glass
• Relatively slow compared to taking a
digital photograph.

29. Space ball and Track ball
• Trackball
 ball rotated to produce screen
cursor movement
 potentiometers attached
measure the amount and direction of
rotation
 mounted on keyboards or mouse

30. • Space ball
 Trackball : 2D positioning devices
whereas space ball provides 6 degrees
of freedom
 Simultaneously pan, zoom or
rotate 3D models scene or camera
datasets with the controller in one
hand, while the other hand selects,
inspects or edits with the mouse

31.  Eliminate tedious and repetitive
steps that put unnecessary stress on
mouse hand
 Used for 3D positioning and
selection operations in virtual reality
systems, modeling, animation and CAD
and other applications

32. Joysticks
• Small, vertical stick mounted on a
base used to steer the screen cursor
around
• Distance moved in any direction from
center position corresponds to
screen cursor movement
• Some respond to stick movement and
others to pressure

33. Joysticks
• Potentiometers mounted at the base
the measure the amount of movement
• Springs return the stick back to
center position
• One or more buttons programmed to
signal certain actions once screen
position is selected

34. ADDITIONAL INPUT
DEVICES

35. Optical Mark Reader
Advantage:
• Good for inputting large volume of
data at low cost.
• Very little training or instruction
required to use the forms/card.
• Good for multi-choice questionnaires.

36. Optical Mark Reader
Disadvantage:
• Can only input a limited data set
• Poorly marked forms/cards cause
errors.
• Creased/folded forms cause errors.

37. Optical Character Reader
• Combination of scanner and special
software that converts printed text into
electronic ASCII characters
• Additional mechanisms to handle multiple
sheets
• Eg 1) Converting paper records into
electronic files.
2) Scanning invoices into spreadsheets

38. • Advantage:
 Allows paper records to be
converted into electronic format
• Disadvantage:
 Conversion is often not perfect
and so someone has to read the
results and correct them.
 Can be slow (unless an
expensive system is used).

39. Magnetic Stripe Reader
• Information is simply encoded in
magnetic form on the strip
• The reader picks up the information
by swiping the card through it and
inputs it to the connected computer
• Eg. Bank card, Credit Card, Security
passes etc.

40. Advantage:
• Inexpensive
• Robust - not easily damaged
• Simple to use
• Fast
Disadvantage:
• A card can be copied fairly easily.
• Sensitive to strong magnetic fields

41. HARD COPY DEVICES

42. • Quality of picture depends on dot
size (spot size) and no. of dots per
inch (addressability)
• In high quality prints, adjacent dots
overlap
• Printers produce output by either
impact or non impact methods
 Impact: press character faces
against inked ribbon onto the paper
 Non Impact: use techniques like
inkjet sprays, electrostatic method…

43. Dot-Matrix Printers
• Print head of 7 to 24 pins
• Each pin fired individually to strike a
ribbon against the paper
• Print head moves across the paper
one step at a time and paper is
advanced one line
• Raster output device requires scan
conversion

44. • Colored ribbon  produce color hard copy
• Two approaches
Multiple print heads: each with
different color ribbon
 Single print head with multicolored
ribbon
• More colors created by overstriking two
different colors at the same dot on the
paper
• With 3 colors upto 8 colors can be created
• Often true black is added to the ribbon

45. LASER PRINTERS
• Positively charged rotating drum is
coated with selenium
• Areas of drum hit by laser beam lose
charge
• Positive charge remains only where
the copy is to be black
• A negatively charged powdered toner
adhere to the positive areas and is
then transferred to the paper

46. • In color xerography: this process is
repeated three times, one for each
primary color
Selenium
coated Laser
drum beam
LASER
Deflection
system

47. Ink-jet Printers
• Two methods
I method
 Spray cyan, magenta, yellow and
sometimes black ink onto the paper
 Ink jets are mounted on a head
 Head moves across page to draw
one scan line, returns while paper
advances

48. II method
 Wrap paper around a drum
 Drum rotates rapidly while print
head moves slowly along the drum

49. Thermal transfer
Printers
• Finely spaced heating nibs transfer
pigments from colored wax paper to
plain paper
• Wax and plain paper are drawn
together over the strip of heating
nibs, which are selectively heated to
cause pigment transfer

50. • For color printing, the wax paper is
on a roll of alternating cyan, magenta,
yellow strips each of length = paper
size
• Nibs heat and cool rapidly, a single
color hard copy image is created in
less than a minute