Bar Coded ID Cards

Bar Coded ID Cards

Posted September 3, 2013 by



In a world fuelled by money, where 6 billion people vie with each other for power, supremacy and money, where each passing year the world economy climbs the ladder of trillions, where the buying and selling of goods has become a necessity, and where time is money; this humble, cute little 10 sq inch zebra pattern like black and white strip never goes unnoticed.

Yes, the BARCODE.



Buying and selling goods were never so easy, never so quick and never so accurate. Contemporary to a world where billions of dollars are shared in a go and billions of goods sold within no time, the need for an accurate, efficient and time saving mechanism to keep track of products and deliver them to the customers in a flash has been fulfilled by this humble little invention.


The Barcode is a one-dimensional, data storing and data representing mechanism which stores useful data in a series of black and white spaces, which are then read by a machine (called a barcode scanner).



- (This is not a barcode for this article)


So how does the barcode work??


Let us not be very technical about its working. Let us just be curious and humble human beings waiting to tap the secret behind this revolutionary invention.

The secret behind the working of a barcode lies in our elementary science principle of reflection of light.

We studied that –

  • Lighter colors reflect more light

  • Darker colors reflect least amount of light.

The application of this simplest phenomenon is what makes barcodes work the way they do.

When the barcode is up for a scan it is illuminated by a high intensity light (LASER) in this case. When the light strikes the black and white strips, it is reflected by the white spaces and absorbed by the black bars.



When the receiver gets the reflected light, the computer assigns a binary ‘0’ to all the white spaces which reflected light and a binary ‘1’ to all the black bars which did not reflect any light.

As the bar code is a one dimensional strip of black and white bars arranged on a 95 column template, a series of 95 binary 1’s and 0’s are assigned to the bars which are further divided into 15 segments.


Again these 15 segments are divided into –

  1. 12 segments with 7 binary digits which form the numbers.

  2. 2 segments with 3 digits which form the left and right ends (empty spaces) called left and right guards.

  3. And a segment with 5 digits which form the middle empty space called the right guard.


  1. The 12 segments with are decodes as shown below tell the computer what the product is.

  2. The 2 other end segments will tell the system where the code ends.

  3. The middle segment tells the system where the 12 numbers start and end.




The left side number gives the “type of item”, the left 5 numbers tells the “manufacturer code” and the right 5 numbers gives the “product code”.


That is it, the light gets reflected, the computer reads and assigns the 1’sand 0’s and, then decodes the digits to the numbers of the barcode and gives its user the complete information of the product. All this happens in fraction of a second.


Now you have successfully decoded one of the simplest mysteries of the universe.


  • Bernard silver and Norman woodland were given the first patent for their “bull’s eye” type bar code in 1952 which never was a bar, but consisted of concentric circles.

  • Early days of barcodes, people used 500 watt light bulb and a photomultiplier to increase the intensity of light in the place of a laser.

  • Troy, wonder what troy has to do with barcodes? The first product scanned UPC product, was a pack of Wrigley’s chewing gum in marsh super market, Troy.

  • Barcodes were first used to locate rail cars in the American province after which their importance was understood in the stores.

Hang on for more interesting stuff.



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