- Currently, the four different types of bar code readers available are the pen type readers (bar code wands), laser bar code scanners, CCD (Charge Couple Devices) barcode readers and camera based barcode readers. Each of these types use a slightly different Technology for reading and decoding a bar code.
- Pen Type Readers or Bar Code wands
Pen type barcode readers have a light source and a photo diode placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars, in a steady even motion. The photo diode measures the intensity of the light reflected back from the light source and generates a waveform corresponding to the widths of the bars and spaces in the bar code. The barcode reader sends the waveform to the decoder, which decodes the waveform and sends it to the computer in a traditional data format.
- Laser Barcode Scanners
Laser barcode scanners work the same way as pen type barcode readers. The only main difference is that Laser barcode scanners use a laser beam as their light source, and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. As with the pen type bar code reader, a photo diode is used to measure the intensity of the light reflected back from the bar code.
- CCD Barcode Scanners
CCD barcode scanners use an array of tiny light sensors lined up in a row in the head of the barcode reader. Voltage waveform corresponding to the bars and spaces of the bar code is generated and sent to the decoder, which decodes the data and sends it to the computer. The main difference between a CCD barcode scanner, a pen type barcode scanner, and laser barcode scanner is that the CCD barcode scanner measures emitted ambient light from the bar code whereas pen or laser barcode scanners measure reflected light of a specific frequency originating from the scanner itself.
- Camera Based Barcode Readers
The camera based barcode readers use a small video camera to capture an image of a bar code. The barcode reader then uses sophisticated digital image processing techniques to decode the bar code.