Bar code scanner and method of scanning

摘要

A method and an apparatus facilitate scanning an Add-On code portion of a bar code label to determine the bar code data printed thereon by sweeping a scanning beam in a scan path across the Add-On code portion of the label. The bar code label includes bar codes of the type which have a primary code portion and which may also have an Add-On code portion. The method includes the steps of: optically scanning the label and producing an electrical signal indicative of the image of the label which includes a possible Add-On code portion; providing data indicative of the structure of the possible Add-On code portion in response to the electrical signal; subjecting the data indicative of the structure of the possible Add-On code portion to at least one test to determine the existence of an adjacent margin; subjecting the data indicative of the structure of the possible Add-On code portion to at least one test to determine the existence of an Add-On guard pattern; decoding the characters of the possible Add-On code portion of the label; and terminating decoding.