Bar code scanning is increasingly being used throughout the supply chain from the warehouse, distribution centre, logistics to the retail point-of-sale system. With the development of automated scanning in the trading processes, it is important that the bar codes are incorporated accurately into the bar packaging and printed in accordance to the set specifications.
Bar codes which fail to meet the minimum quality level may fail to scan thus causing inefficiency in the supply chain. It costs the same to produce a good bar code or printed a badly printed bar code. The following are factors to be taken into consideration when implementing bar code symbol on packaging:
Light Margin Area
Sufficient light margin area is essential. Care must be taken when placing a bar code symbol on a label or package. Light margin area should be free of any wordings, graphics, other markings or closures that may affect the reading of the symbol by scanner. When using stickers, avoid printing the bar code too close to the edge of the label, or printing additional text or lines too close to the bar code.
Please click for the Light Margins and Heights of EAN-13 and EAN-8 Bar Codes.
The Importance of Light Margin Area (LMA)
Light margin area, also known as the quiet zone, is the area that surrounds the bar code. The bar code scanners work on the recognition of the contrast between the dark bars and light spaces. Scanners need to know when a bar code “starts” and when it “finishes” by recognising the light margin area. As such, the light margin area is vital for a correct “read” of the bar code symbol.
The light margin area must be free of any wordings, pictures, graphics or any other markings. Care must be exercised that the dimensions of the light margin areas are respected. (The light margin area dimensions are given in the tables below.)
The light margin area can be indicated by corner marks (Refer to diagram). This is a checking indicator to prevent any printing from encroaching into the light margin areas.
EAN-13 bar code symbol
Light Margin Dimensions for EAN-13 at nominal size (100%)
Light Margin |
Size in mm |
|
Right of bar code |
2.31 |
|
Left of bar code |
3.63 |
EAN-8 bar code symbol
Light Margin Dimensions for EAN-8 at nominal size (100%)
Light Margin |
Size in mm |
|
Right of bar code |
2.31 |
|
Left of bar code |
2.31 |
Size
Size of a bar code is called magnification. Magnification can vary within certain limits. If a bar code symbol is not within these limits, it may not scan. Any reduction in magnification below the nominal size (100%) may reduce reliability. Selecting a magnification higher than the theoretical minimum always enhances reliability of scanning. Manufacturers should also consult their printer before deciding how large a bar code they will have on their pack. Until printability tests have been run on the pack material concerned, it is not possible to say how large the bar code should be.
Please click here for the Retail Bar Codes and Non Retail Bar Codes.
Truncation
Truncating or reducing the height of a bar code is not recommended. Truncation will affect the omni-directional scanning capability of fixed scanners.
Colour and Contrast
Scanners read bar codes by responding to the difference in reflectivity between the dark bars and the light areas. To ensure a good scan there must be sufficient contrast between the dark bars and spaces. Ideally the dark bars should be perfectly black and the light areas should be perfectly white. However, to complement the label design, other combinations of colours, which provide sufficient print contrast, may be used. Cold colours i.e. black, blue, indigo and green are suitable for bars. Warm colours i.e. white, red, orange and yellow are suitable for spaces. Other factor that may affect the reflectivity of the bar code is the type or density of ink and, the substrates used. Other factors such as lamination of a label may result in reflection of the bars above the minimum acceptable.
Colours for Bars
Colours for Space/Background
Location
Consistency on the location of bar code symbol on packaging will increase scanning efficiency. Speed at the checkout counter increases if the checkout operator can predict where the symbol is on the item. The general guidelines are:
- Human readable characters must be visible and clear.
- Bar code symbol must be printed on a reasonably smooth surface. Avoid printing on the folds, creases, seams, joins, etc.
General Rules for Location of Bar Code Symbol on Curved Surfaces
When printing bar code symbol on a curve surface, proper consideration must be given on the orientation and size of the symbol. For example, if a bar code on a curve surface is in a picket fence orientation, both ends of the symbol would wrapped around the surface and would not be visible to the scanner at the same time during scanning. The bar code would not be scannable.
Therefore, when printing a bar code symbol on curve surface, it is preferable for the bars to be perpendicular to the generating lines of the surface of the container. This way the scan line or laser beam of the scanner can pass through the symbol on a nearest flat surface as possible (please refer to the diagram below).
With the ladder orientation, the bar code symbol can be read either from the top down or from the bottom up, whichever is consistent with other text and graphics on the container. The ladder style orientation is mandatory for a curve with small diameter. A small diameter is when the angle between the line touching the centre of the curved bar code (a) and the line touching the outer edge of the guard bars (b) exceed 30o as shown in the diagram.
