A brief on bar code readers and their types

A brief on bar code readers and their types

A barcode reader, also known as a barcode scanner, is an optical scanner that can read printed barcodes, decrypt what they contain, and communicate the information to a computer. It uses a light source, a lens, and a light sensor that converts optic impulses into electrical signals, like that of a flatbed scanner. Furthermore, practically all barcode readers include decoder circuitry capable of analysing barcode picture data given by the sensor and delivering the barcode’s information to the scanner’s output node.


  • Pen-type: A light source and photodiode are placed next to each other at the tip of a pen in pen-type readers. The individual holding the pen must move the tip across the bars at a roughly uniform speed to read a barcode. As the tip crosses each bar and space in the printed code, the photodiode measures the intensity of the light reflected from the light source.
  • Phone cameras: While auto-focus cell phone cameras are not perfect for scanning some common barcode formats, there are 2D barcodes, QR codes, and Data Matrix codes that can be read rapidly and precisely with or without auto-focus.
  • Laser scanner: A photodiode, like the pen-type reader, measures the intensity of the light reflected from the barcode. The light emitted by the reader is rapidly varied in brightness with a data pattern in both pen readers and laser scanners, and the photodiode receive circuitry is intended to identify only signals with the same modulated pattern.
  • LED scanner: Also known as CCD, the head of a charge-coupled device (CCD) reader contains an array of hundreds of small light sensors lined up in a row. Each sensor determines the brightness of the light directly in front of it. Because each light sensor in the CCD reader is so small, and because there are hundreds of them lined up in a row, the reader generates a voltage pattern that is identical to the pattern in a barcode by progressively measuring the voltages across each sensor in the row.
  • Omnidirectional scanner: Horizontal scanners at supermarkets, where packages are pushed over a glass or sapphire window, are the most familiar omnidirectional scanners. There are a variety of omnidirectional scanners available that may be used for a variety of scanning applications, ranging from retail scanning where barcodes are read-only a few centimetres away from the scanner to industrial conveyor scanning where the scanner is a couple of meters away or more.


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