A little bit of history
Mr Woodland and Mr Silver, who were teaching at Drexel University in Philadelphia, began the work that led to the barcode after the head of a supermarket chain asked for help in developing a better way to keep track of inventory. A former Boy Scout, Woodland wondered if Morse Code could be used to track inventory, and began drawing lines of different thickness in the sand during a visit to Miami in 1948. The code that eventually emerged is now known as Universal Product Code, and Woodland won the National Medal of Technology in 1992.
What is a Barcode?
A barcode is an optical machine readable representation of data, which shows data about the object to which it attaches.Originally barcodes represented data by varying the widths and spacings of parallel lines, and therefore were referred to as linear or one-dimensional (1D). Later they evolved into rectangles, dots,hexagons and other geometric patterns in two dimensions (2D).
So how do Barcodes work?
A Barcode is simply machine readable language. The barcode is a set of lines and spaces that represents a set of characters. These characters can be alphabetic or numeric depending on the type of barcode used. Below are some individual letters and characters.
A barcode reader uses a photo sensor to convert the barcode into an electrical signal as it moves across a barcode. The scanner then measures the relative widths of the bars and spaces, translates the different patterns back into regular characters, and sends them on to a computer or portable terminal. Every barcode begins with a special start character and ends with a special stop character. These codes help the reader detect the barcode and figure out whether it is being scanned forward or backward.
Some barcodes may include a checksum character just before the stop character.A checksum is calculated when the barcode is printed using the characters in the barcode. The reader performs the same calculation and compares its answer to the checksum it reads at the end of the barcode. If the two don’t match, the reader assumes that something is wrong, throws out the data, and tries again.
Important elements of the barcode
X dimension: The width of the narrowest bar or space is referred to as the X dimension, usually given in mils (thousandths of an inch). The X dimension dictates the width of all other bars and spaces, and ultimately the length of the bar code.
Left & Right Light Margins (Quiet Zones): These are the areas before and after a code that must be left clear to enable the scanner to correctly read the barcode, it has a direct relationship to the “X dimension”, the wider the X dimension the wider the left/right light margin requirement
Barcode Symbology Density: This is the rate of information that can be stored in the barcodes, a Code 128 barcode has a higher symbology density than a Code39 or Codabar barcode.
Barcode Ratio: This is the ratio of wide to narrow elements and helps to configure the width of the final code, the bigger the ratio the wider the final barcode.
Human Readable: The data represented by the bars and spaces printed as text for people to read.
IMPORTANT ADVICE: Remember that the data contained in the eye readable may not reflect the data contained with the barcode itself – ALWAYS SCAN TO CHECK – NEVER ASSUME!!!!!!
Linear (1Dimensional Barcodes: A barcode that encodes data only in one dimension. Data is encoded in the widths of the bars and spaces and no data is encoded in the lengths of the bars.The EAN or UPC barcode symbology found on many retail products is a common linear barcode that you may be familiar with.
2 Dimensional Barcodes:
The need for ever increasing amounts of information in smaller spaces has lead to more compact and higher data density symbologies found in two dimensional or stacked barcodes.
A two-dimensional symbology is either:
- “matrixed” as in the data matrix code
- “stacked” as in the PDF417 code.
Each type allows more information to be stored in a smaller amount of space.
Benefits of Barcoding
- Represent unique identity of a product.
- Accuracy of data input. (Error free)
- Aid effective management of resources
- Saves labour By avoiding manual inputting system.
- Real time data collection.
- More accurate despatch.
Colours of barcode – does it matter?
Always ensure that coloured barcodes and backgrounds meet requirement for scanning acceptability.