How do the lines on a bar code and a scanner of bar codes work?

Answer 1

Most bar codes you will see on consumer products have the numbers below.

A Bar code is a way of making information readable to a machine.

It does this, similar to Morse Code, by encoding normal letters and numbers as patterns of thick and thin black lines.

The purpose of the bar code is to tightly control the comparison between the thick and thin lines, and the space in between, so that the pattern has a high chance of being read correctly.

Every letter in the alphabet has a corresponding bar code character, when the bar code reader scans the bar code its electronics translate the bar code into the letters, and send these letters in machine code to the computer.

Some bar code readers use what is called a "wedge" - they are plugged in between the keyboard and the computer, and send signals into the keyboard port of the computer exactly as if the operator had typed in the numbers on the bar code.

Answer 2

CCD barcode scanners work by illuminating the code with a red light, which is then reflected off, and collected by a scanner. The scanner analyzes the patterns, and decodes the code into ASCII text which can be read.

Answer 3

Barcode scanners read light intensity. For pen type scanners or laser scanners they will use a photodiode to measure the amount of light intensity reflected back from the bar code. LED scanners have hundreds of sensors that measure the light intensity directly in front of them which causes a voltage pattern to be generated identical to the pattern of the bar code being read.