What is a Bar Code reader? 

A bar code reader is also known as a bar code scanner. Now a days Wireless bar code scanners are very popular. They don't require communication cable. A bar code is a specialized way of encoding letters and numbers using a combination of spaces and bars of variable widths. It feeds data into a computer in different way. 

It does not contain descriptive data. It is interesting to see how does it work? A computer uses a reference number, which look up a related record that contains descriptive data and other important information.

Whenever you go to a bookstore, a barcode found on a book or when you go to a general store and purchase a soft drink can you will find a bar code on the can instead of the product name, type of a soft drink, or price. Bar code is made up of bars and spaces along with a 12-digit product number.

When it is scanned by the cashier at the checkout counter it decodes the information and transmit it to the computer which finds the record related with that item number in the data base. The matching record decodes and displays the information of the product, price, discounted price, available quantity and vendor name etc. 

Bar code Kit 

A kit of bar code reader consists of scanner, decoder, and cable, which interface the decoder to the computer. The function of scanner is to scan the Bar Code symbol and to read the bars and spaces of the bar code. Finally it sends this information to the decoder. The decoder converts the bars and spaces into corresponding electrical pulses and transmits that data to the computer in a traditional data format.

Since Computer is not able to read bar codes. A special device, i.e. bar code reader is required this device reads and scans the bar code information and sends it to the decoder. Finally the decoder decodes bar code data into a data format that computer can process.

Types of bar code readers

There are four types of bar code readers available. They differ in technology used for reading and decoding a bar code.

*Pen Type Readers

*Laser Scanners

*CCD Readers

*Camera-Based Readers

Pen Type Readers:  

Pen type readers has an in built photo diode and a light source behind it at a tip of the pen. To read a bar code the tip of the pen should move across the bars. The photo diode plays an important role here, it measures the intensity of the light reflected back from the light source and generates a wavelength that is used to measure the widths of the bars and spaces in the bar code. This wavelength is decoded by the scanner. 

Laser Scanners:

Laser scanner is based on same principle as pen type readers. The only difference is that it uses a laser beam as the light source. In both pen readers and laser scanners, the light emitted by the reader is tuned to a specific frequency and the photo diode is designed to detect this specific frequency of light.

CCD Readers:

CCD is an acronym of Charge Coupled Device. CCD readers use an array of numerous tiny light sensors lined up in a row in the head of the reader. The main difference between a CCD reader and a pen or laser scanner is that the CCD reader measures emitted ambient light from the bar code whereas pen or laser scanner measures reflected light of a specific frequency originating from the scanner itself.

Camera Based Readers:

Camera based reader is the latest type of bar code reader. It uses a small video camera to take an image of a bar code. The sophisticated digital image processing technology is used to decode the bar code.  

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