What is bar code ? How does bar code Works ? Write the application areas of bar code readers.

Subject Introduction to Computer System
NU Year Set: 2.(c) Marks: 4 Year: 2009

What is a Barcode?

A barcode is a square or rectangular image consisting of a series of parallel black lines and white spaces of varying widths that can be read by a scanner. Barcodes are applied to products as a means of quick identification. They are used in retail stores as part of the purchase process, in warehouses to track inventory, and on invoices to assist in accounting, among many other uses.

How does barcode works:

It would be no good having barcodes if we didn't have the technology to read them. Barcode scanners have to be able to read the black-and-white zebra lines on products extremely quickly and feed that information to a computer or check-out terminal, which can identify them immediately using a product database. Here's how they do it.

For the sake of this simple example, let's assume that barcodes are simple on-off, binary patterns with each black line corresponding to a one and each white line a zero. (We've already seen that real barcodes are more sophisticated than this, but let's keep things simple.)

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.

Application of barcode readers:

·         Barcodes are used in admission tickets in movie theaters and other events to uniquely identify and verify the validity of the ticket before the customer can enter the theater or the event. 

·       Advertisers are taking advantage of barcodes by using them to reach out to customers in a more interactive, interesting, and unique way. With the use of smartphones, just by downloading and installing an app that can read barcodes you can discover a lot more information about the product being advertised.

·         Barcodes have become so popular that they have been used as inspiration for art and architecture. This building in St. Petersburg, Russia has been designed with the linear (traditional) barcode in mind

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