What Are Barcodes and How Are They Read?
Barcodes are everywhere. They are on the side of your soda bottle, on soup can labels, printed in advertisements and engraved almost every engine part in your car. But, what are barcodes and why are they used?
A barcode is a machine-readable pattern applied to products, packages or parts. It contains data used for informational and marketing purposes as well as for tracking products throughout their lifecycle. Barcode technology was originally patented in 1952, but it wasn’t until 1974 that the first barcode was scanned on a package of Wrigley’s gum.
Barcodes come in dozens of different formats which fall into 2 main categories:
- One-dimensional (1-D) barcodes: contain data in the horizontal direction and can hold up to 25 characters
- Two-dimensional (2-D) matrix codes:contain information both vertically and horizontally and can hold significantly more—up to 2,000 characters
Figure 1: Selection of 1-D and 2-D code formats
Traditionally, 1-D barcodes have been “read” by laser scanners. With this technology, a laser beam hits a rotating prism that directs the beam onto the barcode, where a sensor is used to capture the light intensity that is reflected back, distinguishing between black and white bars. This scanning method has several limitations. Laser scanners use mechanical rotating or oscillating mirrors or prisms that wear out and can easily be damaged from shock or vibration. Also, they are unable to read 2-D codes, which are increasingly used in consumer and industrial applications ranging from aerospace and automotive to food and pharmaceuticals.
Figure 2: How a laser-based barcode reader works
Vision-enabled barcode readers are emerging as the technology of choice for many industries for two main reasons:
- There are no moving parts that can wear out or fail, making them ideal for industrial applications
- They are also able to read 2-D codes ideal for industries needing to store detailed information about the product
Figure 3: How a vision-enabled barcode reader works
To learn more about the different types of codes and how they are most commonly used, download Let’s Talk Symbology—A Guide to Decoding Barcodes