Working principle of a barcode Reader

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

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 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. 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. 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 Universal Accuracy Productivity Time Savings Employee Training Inventory Control Disadvantages Cost Range Physical Damages Label Damages Information Security