DATA RETRIEVAL AND ERROR DETECTION METHOD AND APPARATUS DESIGNED FOR USE IN A WIDTH-MODULATED BAR-CODE SCANNING APPARATUS

摘要

Abstract of the DisclosureSudden changes in the rate at which a bar code ismanually scanned are detected by circuitry which comparesthe time required to scan adjoining fixed-width charactersof the bar code. This circuitry sums the time required toscan each individual bar and space element of every characterin the bar code. The circuitry thereby generates a series ofnumbers proportional to the widths of the characters whichcomprise the bar code. Adjacent numbers in this series arethen compared to determine if there has been a sudden,unacceptable change in the speed at which the bar code isscanned. If adjacent numbers differ in size by an unaccept-able amount, an error indication is given out.