Touch Screens and Scanner

INPUT DEVICES
TOUCH SCREEN AND SCANNERS
HEM SAGAR POKHREL
FACULTY MEMBER, LECTURER
COMPUTER SYSTEMS AND IT APPLICATIONS
PRIME COLLEGE
Unit II

TOUCH SCREEN
▪ Screen with touch sensitive points
or program icons.
▪ When specific point or icon is
touched by fingertips, related
programs or prompts are activated.
▪ Mainly three types:
▪ Capacitive
▪ Infrared
▪ Pressure Sensitive.
Class handsout | BBA 1st Semester | Sagar Pokhrel, Faculty - CSITA , Prime College

CAPACITIVE TOUCH SCREEN
✓ A capacitive touch screen
panel is one which consists
of an insulator such as glass,
coated with a transparent
conductor such as Indium
tin oxide (ITO).
✓ As the human body is also a
conductor, touching the
surface of the screen
results in a distortion of the
screen's electrostatic field,
measurable as a change in
capacitance.

RESISTIVE TOUCH SCREEN
✓ A resistive touch screen panel
is composed of several layers,
the most important of which
are two thin, electrically
conductive layers separated by
a narrow gap.
✓ When an object, such as a
finger, presses down on a point
on the panel's outer surface the
two metallic layers become
connected at that point
✓ This causes a change in the
electrical current, which is
registered as a touch event and
sent to the controller for
processing.

OTHER TOUCH SCREEN
TECHNOLOGIES
✓ Resistive touch screen
✓ Capacitive touch screen
▪ Surface acoustic wave touch screen
▪ Infrared touch screen
▪ Acoustic pulse technology
▪ 3M Dispersive Signal Technology (DST)

SURFACE ACOUSTIC WAVE TOUCH
SCREEN
✓ Surface acoustic wave (SAW)
technology uses ultrasonic waves(sound
waves) that pass over the touch screen
panel in horizontal and vertical direction
across a glass plate.
✓ When the panel is touched, a portion of
the wave is absorbed.
✓ This change in the ultrasonic waves
registers the position of the touch event
and sends this information to the
controller for processing.
✓ Compatible only with fingers and soft
objects such as gloves which absorb
sound waves.
✓ Requires special-purpose stylus and may
react to substances like water drop or
small insects on the panel.Class handsout | BBA 1st Semester | Sagar Pokhrel, Faculty - CSITA , Prime College

INFRARED TOUCH SCREEN
▪ An infrared touch screen uses a ray of
X-Y infrared LED and photodetector
pairs around the edges of the screen to
detect a disruption in the pattern of
LED beams.
▪ These LED beams cross each other in
vertical and horizontal patterns. This
helps the sensors pick up the exact
location of the touch.
▪ Also called as optical touch panel.
▪ A major benefit of such a system is
that it can detect essentially any input
including a finger, gloved finger, stylus
or pen.

MULTI-TOUCH TECHNOLOGY
▪ On touchscreen displays, multi-touch refers to the
ability to simultaneously register three or more
distinct positions of input touches.

ADVANTAGES | TOUCH PANELS
✓ User friendly
✓ Fast response
✓ Error free input
✓ User finger, finger nail, gloved hand, stylus or any
soft tip pointer to operate
✓ Make computing easy, powerful and fun

DISADVANTAGES
▪ 1)Finger stress: Stress on human fingers when used for
more than a few minutes at a time. (for example,
ATMs).
▪ 2)Fingerprints: Touchscreens can suffer from the
problem of fingerprints on the display.

CONCLUSION
Though the touch screen technology contains
some limitations with it, it is fast, accurate, user
friendly and fun to operate .It is being widely
accepted.
With some modifications, it can completely
replace mouse and keyboard completely in the
near future.

SCANNERS
DATA SCANNING DEVICES
HEM SAGAR POKHREL

DATA SCANNING DEVICES
• Input devices that enable direct data entry into a computer
system from source documents
• Eliminate the need to key in text data into the computer
• Due to reduced human effort in data entry, they improve
data accuracy and also increase the timeliness of the
information processed
• Demand high quality of input documents
• Some data scanning devices are also capable of recognizing
marks or characters

IMAGE SCANNER
• Input device that translates paper documents into
an electronic format for storage in a computer
• Electronic format of a scanned image is its bit map
representation
• Stored image can be altered or manipulated with
an image-processing software

2 COMMON TYPES OF IMAGE
SCANNERS
I. Flat - bed Scanner
II. Hand - held Scanner

FLAT - BED
SCANNER
▪ Looks Like a photocopy machine
▪ Has a box with a glass plate on the top & a
lid.
▪ Sometimes called as stationary scanners and
usually fixed in one place.
▪ Document to be scanned is placed on the
glass plate.
▪ A light source below the glass plate moves
from 1 line to the another & scans all the
lines.
▪ Takes few seconds to scan a document.

HAND – HELD
SCANNER
▪ Contains LEDs & can be held in hand.
▪ To scan, dragged slowly over the document
from 1 end to another.
▪ Has to be dragged very slowly & steadily.
▪ Used only when high accuracy is not needed.
▪ Cheaper than a flatbed scanner.
▪ Used when volume of documents to be
scanned is low.

LIMITATIONS OF IMAGE SCANNERS
▪ Scanned document is stored as an
image & not as text. So it is not
possible to do any word processing
of the document.
▪ Storage space required is more for
an image than text.

OCR – OPTICAL CHARACTER RECOGNITION
▪ Scanner with a character recognition software (called
OCR software) that converts the bit map images of
characters to ASCII codes.
▪ Enables word processing of input text and also requires
less space for storing the document.
▪ OCR software is extremely complex because it is difficult
to make a computer recognize an unlimited number of
fonts
▪ Two standard OCR fonts are OCR-A (American standard)
and OCR-B (European standard)

OPTICAL CHARACTER RECOGNITION
OCR-A
FONT
OCR-B
FONT

MICR – MAGNETIC INK CHARACTER
RECOGNITION
▪ MICR is used by banking industry for faster processing of
large volume of cheques.
▪ Bank’s identification code (name, branch, etc.), account
number and cheque number are pre-printed
(encoded)using characters from a special characters on all
cheques.
▪ Special ink is used that contains magnetizable particles of
iron oxide.
▪ MICR reader, reads data on cheques and sorts them for
distribution to other banks or for further processing.

MICR CHARACTER SET

MICR – MAGNETIC INK CHARACTER
RECOGNITION
▪ The first three digits in the MICR code represent the city code that is the city in
which the bank branch is located. The next three digits stand for the bank code
while the last three digits represent the bank branch code.
▪ For example, if you have an account with NCC Bank, Kathmandu(Newroad)
then its nine digit MICR code may be like 110211004 where:
▪ 110, the first three digits representing the city code for KTM;
▪ 211, the next three digits representing the bank code for NCC Bank;
▪ And 004, the last three digits representing the bank branch code for Newroad
Branch.
▪ Apart from being a security bar code to protect your transaction, the MICR
code is also an essential part for online money transfers. Every bank branch is
given a unique MICR code and this helps the NRB to identify the bank branch
and speed up the clearing process.Class handsout | BBA 1st Semester | Sagar Pokhrel, Faculty - CSITA , Prime College

OMR – OPTICAL MARK READER
• Scanner capable of recognizing a pre-specified
type of mark by pencil or pen
• Very useful for grading tests with objective type
questions, or for any input data that is of a choice
or selection nature

OMR-OPTICAL MARK READER

OMR SHEET

BAR CODE READER
SUPPLIER
IDENTIFIC
ATION
NUMBER
SPECFIC
PRODUC
-T CODE
NUMBER

BAR CODE READER
▪ Scanner used for reading (decoding) bar-coded data
▪ Bar codes represent alphanumeric data by a combination
of adjacent vertical lines (bars) by varying their width and
the spacing between them.
▪ Scanner uses laser-beam to stroke across pattern of bar
code. Different patterns of bars reflect the beam in
different ways sensed by a light-sensitive detector.
▪ Universal Product Code (UPC) is the most widely known
bar coding system.
▪ How

AN EXAMPLE

DIGITIZER
▪ Input device used for converting (digitizing) pictures,
maps and drawings into digital form for storage in
computers
▪ Commonly used in the area of Computer Aided Design
(CAD) by architects and engineers to design cars,
buildings medical devices, robots, mechanical parts,
etc.
▪ Used in the area of Geographical Information
System(GIS) for digitizing maps available in paper form

ELECTRONIC CARD READER
▪ Electronic cards are small plastic cards having encoded data
appropriate for the application for which they are used
▪ Electronic-card reader is used to read data encoded on an
electronic card and transfer it to the computer for further
processing
▪ Used together as a means of direct data entry into a computer
system
▪ Used by banks for use in automatic teller machines(ATMs) and
by organizations for controlling access of employees to
physically secured areas

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