A.3 Bar Code Basics and Scanning Tips
A Closer Look At Bar Code Symbols |
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The illustration at the right shows a typical bar code |
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symbol. If you look at it closely, you’ll see it is |
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composed of a series of dark lines (bars) and white | 0 |
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areas (spaces) of various widths. By arranging these |
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bars and spaces in a certain order, it is possible to |
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represent, or “encode” letters, words and numbers. |
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| 42000 |
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| 06200 | ||||||||||||
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You may also print the numbers represented by the bar code symbol on the label. These human readable characters allow you to know exactly what information the scanner is sending to the register or terminal. The human readable characters under the bar code symbol also allow you to key in information in case the bar code symbol is not readable.
The blank area located just before and just after the bar space pattern is called the “quiet zone.” It is placed on the symbol so the scanner knows exactly where the bar code begins and ends. It is important to remember where the quiet zone is located so you can scan accurately.
Bar Code Scanning
The purpose of the bar code scanner is to “read” the image formed by the bars and spaces. A signal sends the information printed on the bar code symbol to the terminal.
Several types of scanners are in use today. The most common types include the wand scanner, the laser scanner, and the CCD scanner. All scanners use optical systems which are protected by “windows” at the scanning end to read the bar code symbol. On wand scanners, the window is located in the tip. Laser and CCD scanners have a larger and more noticeable viewing “window.” It is important to keep these optics clean, because just like the lenses on reading glasses, if they become dirty, scratched or smudged, they won’t work properly.
If your scanner is attached to a decoder (or it is also a decoder), the decoder may have a beeper that will let you know when a scan has been performed properly and that the bar code has been read accurately. After you’ve scanned a symbol, listen for a single beep, (called a “good read” beep). This lets you know that the bar code information has been received by the terminal. If you don’t hear the single beep or if you hear several beeps, it means the symbol is unacceptable to the decoder, and the terminal has not received the bar code information. If that happens, try scanning the symbol again.
Before using any scanner, make sure the symbol is of good quality and that the optic area of your scanner is clean. Any dirt or specks in the bar code symbol or on the scanner optics may prevent it from reading accurately. Even a symbol that is smudged during printing, or gets wrinkled when it is applied to an object can cause a reading problem. If you can’t get a good read beep or you begin to receive error beeps, be sure to check the scanner optics and the symbol. The decoder may need to enable the beeper, either with a hardware configuration or with a software command.
CCD Operation and Bar Code Scanning |
