Symbology scanning system for efficiently locating coded symbologies

• US 20020139851A1
• Filed: 12/18/2001
• Published: 10/03/2002
• Est. Priority Date: 03/07/1997
• Status: Active Grant

• Current Assignee: Accu-Sort Systems Incorporated (Datalogic S.p.A.)
• Original Assignee: Accu-Sort Systems Incorporated (Datalogic S.p.A.)
• Inventors: Hecht, Kurt
• Granted Patent: US 6,508,404 B2
• Time in Patent Office: Days
• US Class Current: 235/454
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1443 locating of the code in an image

Abstract

A scanner for optically scanning coded symbologies including a signal processing unit for pre-processing the scanned symbology information and a hardware symbology locating unit. An analog signal related to the reflectivity of the different portions of the coded symbology is obtained and is converted to digital gray-scale. The portion of the analog signal which corresponds to the substrate reflectance (absolute contrast) is removed, and the available dynamic range of the analog to digital converter is used only for the information-bearing portion of the signal (relative contrast). Since all of the decodable information is ultimately encoded in binary form, the information-bearing portion of the signal is retained. The hardware symbology locating unit includes a plurality of shift registers, each of which derives a value from an input seed which is based upon the width of a detected coded symbology element. The value of a subsequent input seed is compared to the values generated from a prior input seed. Based upon this comparison, the unit determines whether the size of a subsequent symbology element is a ratio match of a prior symbology element. The presence of a potential coded symbology candidate is likely when a plurality of ratio matches are detected.

Claims

1. A coded symbology scanner comprising:

means for illuminating a scanned region;

means for detecting light reflected from the scanned region for generating a detected light intensity signal that corresponds to transitions in reflectivity over the scanned region; and

means for processing the light intensity signal, the processing means comprising;

means for generating a series of counts from the light intensity signal, each count corresponding to a transition between a higher and a lower intensity;

means for determining the ratio between successive counts; and

means for locating a coded symbology based upon the successive count ratios.