By T Mylsami
A barcode is an optical machine readable representation of data, which indicates certain information about a certain product. Originally, barcodes represent data in the width and spacing of parallel bars or lines, and are referred to as linear or one dimensional (1D) barcodes or symbologies. Now, they also come in patterns of squares, dots, hexagons and other geometric patterns termed as two dimensional (2D) matrix codes or symbologies. Although 2D systems use symbols other than bars, they are generally referred to as barcodes as well. Barcodes can be read by optical scanners called barcode readers, or are scanned from an image using special software.
There are many benefits of barcode systems that fulfill different needs. Barcode data collection systems result in faster and more accurate data capture, lower costs, minimal mistakes and easier inventory management.
Types of barcode systems
A barcode symbology defines the technical details of a particular type of barcode—the width of the bars, the character set, the method of encoding, checksum specifications, etc. Most users are more interested in the general capabilities of a particular symbology rather than in the technical details.
There are different types of barcode systems/methods employed in various fields. Some of the important ones are:
- Numeric only barcodes
- Alphanumeric barcodes
- 2D barcodes
- Retail barcodes
- DataBar expanded
- DataBar 14
- Coupon barcodes
- Packaging barcodes
- Publishing barcodes
- Barcodes for non-retail labels
- Pharmaceutical barcodes
Functional operations of barcode systems
A single barcode number has seven units which are either black or white. A black unit is displayed as a ‘bar,’ whereas a white unit is displayed as a ‘space.’ Another way of writing a barcode unit is ‘1’ for a single unit ‘black bar’ and ‘0’ for a single unit ‘white space’. For instance, the number ‘1’ is composed of seven units, ‘0011001’ or ‘space-space-bar-bar-space-space-bar.’
In a universal product code (UPC) barcode, the same numbers on the left hand side (the manufacturer code) are coded differently from the numbers on the right hand side (the product code). The numbers on the left are actually the ‘inverted’ or ‘mirrored’ codes of the numbers on the right.
Figures 1 and 2 show the left and right side codes matching the corresponding numbers, separated into seven single units. For instance, a ‘bar’ on the right side is a ‘space’ on the left. The right side codes are called ‘even parity’ codes because there is an even number of ‘black bar’ units.
For instance, ‘6’ on the right side is ‘101000’, with two even numbered ‘black bar’ units. The code on the left is called ‘odd parity’ because there are an odd number of ‘black bar’ units. For instance, the left side ‘6’ is ‘0101111’ with five odd numbered ‘black bar’ units. Having different coded numbers for each side allows the barcode to be scanned in either direction.
Basics about barcodes
Every barcode number is equal to four different ‘marks’. A ‘mark’ can be either black (bar) or white (space). The ‘marks’ vary in width, but there are always four different marks—two ‘bar marks’ and two ‘space marks’.
The left side code always begins with a ‘space’ or ‘0’ and ends with a ‘bar’ or ‘1’. The right side code is just the opposite; it begins with a ‘bar’ or ‘1’ and ends with a ‘space’ or ‘0’. Figure 3 shows the sample format of a barcode. The various parts in which the barcode structure can be divided are given below.
Manufacturer code: This is a five digit number specifically assigned to the manufacturer of the product. The manufacturer codes are maintained and assigned by the Uniform Code Council (UCC). Every product that the manufacturer makes carries the same manufacturer code.
Product code: This is a five digit number that the manufacturer assigns for a particular product. Every different product, and even those in different packaging or sizes, gets a unique product code. A manufacturer can have 99,999 unique product codes. The product code is marked in Figure 3 in orange.
Three guard bars: There are three guard bars highlighted in green in Figure 3, at the beginning, middle and the end of the barcode. The beginning and ending guard bars are encoded as ‘bar-space-bar’ or ‘101’. The middle guard bar is encoded as ‘space-bar-space-bar-space’ or ‘01010’. The guard bars tell the computer scanner when the manufacturer and product codes begin and end. For example, when the computer scanner reads the first ‘101’ or guard bar, the computer knows the next series of numbers is either the manufacturer or product code. Similarly, when the scanner reads the ‘01010’ or middle guard bar, the computer knows another number is coming.
Number system character: This number is a UPC system number that characterises specific types of barcodes. A UPC barcode is normally on the left side of the barcode. The actual barcode (the ‘bars’ and ‘spaces’) is the one after the first ‘guard bar’. The number system character is represented in blue in Figure 3.
Check digit: Also called the ‘self-check’ digit, this is on the outside right of the bar code. The check digit is an old programmer’s trick to validate that the other digits (number system character, manufacturer code and product code) are read correctly. It is marked in red in Figure 3.
In general, no special bar is mentioned or used for pricing a product. When the scanner at the checkout line scans a product, the cash register sends the UPC number to the store’s central point of sale (POS) computer to look up the UPC number. The computer sends back the actual price of the item at that moment. This approach allows the store to change the price whenever required. If the price was encoded in the barcode, it could never be changed so easily.
Zero suppressed numbers
There are also short barcodes, called zero suppressed numbers. There is a set of rules around forming zero suppressed numbers from full numbers, but the basic idea is to leave out a set of four digits—all zeros. The main reason for having zero suppressed numbers is to create smaller barcodes for small product packages like 355 ml cans.
Benefits of barcodes
Improves operational efficiency
Since barcodes help in speedy and more accurate recording of information, work can be done faster and be tracked easily. Barcodes can help you keep better track of your products so that you can save time, and respond quickly to enquiries and changes.
Depending on the application, your inventory time can be cut down significantly. You can also reduce the number of people looking into inventory work. Even in routine day-to-day operations, the time saved due to the use of barcodes adds up and improves productivity. You can also save time and money by utilising barcodes for your own operations. For example, you can collect shipping information quickly and accurately by scanning the barcode labels that you printed to satisfy your customer.
Data entry errors can be a significant cause of higher costs and other related problems—extra freight costs, unhappy customers, and the time wasted in tracking down problems, are just a few examples. Barcode scanners are much more accurate—the error rate can be as low as 1 error in 36 trillion characters, depending on the type of barcode used.
Barcodes are effective tools that can be used to address specific, localised problems or be integrated into organisation wide information systems. When used with careful planning, they can save time and reduce errors, resulting in a reduction of operational costs.