A barcode scanner is an input device that uses light beams to scan and digitally convert printed barcodes. It then decodes the data and sends the data to a computer. It consists of a lens, a source of light, and a light sensor that can translate optical impulses into electrical signals

1. Working principle of Barcode reader
Marajul Islam
16CSE038

2. Outlines
What is barcode reader?
What are the components of a barcode?
What is the difference between
barcode and QR code?
What is barcode?

3. Barcode and barcode reader
Figgure1: Bar-Code
Figgure2: Bar-Code reader
Figgure3: QR-Code

4. Components of barcode reader
• A barcode reader consists of
• A scanner ,
• A decoder (either built-in or external), and
• cable used to connect the reader with a computer
• Barcode scanners can be connected to a computer through a
• serial port ,
• keyboard port ,
• an interface device called a wedge.

5. Working
process of
barcode
reader
• Scanning head shines LED or laser light onto barcode.
• Light reflects back off barcode into a light-detecting
electronic component called a photoelectric cell. White areas
of the barcode reflect most light, black areas reflect least.
• As the scanner moves past the barcode, the cell generates
a pattern of on-off pulses that correspond to the black and
white stripes. So for the code shown here ("black black black
white black white black black"), the cell would be "off off off
on off on off off."
• An electronic circuit attached to the scanner converts these
on-off pulses into binary digits (zeros and ones).
• The binary digits are sent to a computer attached to the
scanner, which detects the code as 11101011.

6. • Figure4 : Barcode extracting process

7. Types of bar code scanners
CCD method
 Laser light is shwon on
the label surface and its
reflection is captured by a
sensor (laser photo
detector) to read a bar
code.
 A laser beam is reflected
off a mirror and swept left
and right to read a bar
code Using laser allows
reading of distant and
wide bar code labels.
Pen method
 This method only has a
LED light source and a
sensor to capture its
reflection.
 Since a person moves
a scanner to read a bar
code, practice is
required for operation.
 The mechanism is
simple, making this
method inexpensive.
Laser method
 A oscillating mirrors or rotating
prisms to scan the laser beam back
and forth across the barcode.
 A photodiode then measures the
reflected light from the barcode.

8. Advantages
1.Universal
2. Accuracy
3. Productivity
4. Time Savings
5. Employee Training
6. Inventory Control
Disadvantages
1.Cost
2. Range
3. Physical Damages
4. Label Damages
5. Information
6. Security