Bar code decoder with changeable working ranges

Abstract

An arrangement for decoding a bar code symbol in which the data resulting from scanning a bar code symbol with a bar code scanner is evaluated to determine if the scanned bar code symbol is within the working range of the scanner. The data acquired by the bar code scanner is evaluated to determine if the detected widths of the bars and spaces of the scanned bar code symbol are too small, less than a threshold value, which indicates that the bar code symbol is too far and outside of the working range of the scanner. Moreover, the working range of the bar code scanner can be selectively changed by changing the threshold value, which can be easily implemented by having the bar code scanner scan a menu bar code which instructs the decoder to change the threshold value to a selected new value which may be pre-established for the particular operation. The arrangement preferably includes software to process the data acquired by the bar code scanner, and if the data indicates that the scanning distance to the bar code is too far, a flag is set in the software which prevents a new decode result from being recorded. However, the intermediate decode result is retained in memory to indicate that the bar code symbol is still in the scanner's field of view. A second evaluation validation to determine if the detected bar code symbol is valid may also be performed.