Bar code reader system for reading bar code labels with a highly specular and low contrast surface

A system for scanning a surface with alternating areas of high specularity and low contrast, the dimensions of these alternating areas being representative of information of an item so bar coded, comprising:

• means for receiving radiation in a primary state as it is reflected from said surface wherein radiation received from the high specularity areas is polarized in a first direction and radiation received from the low contrast areas is depolarized, thereby creating a high radiation output for high specularity areas and a low radiation output for low contrast areas;
• means for converting received radiation to a secondary state by blocking radiation polarized in said first direction representative of said high specularity areas and allowing to pass other radiation representative of said low contrast areas resulting in a radiation pattern wherein the radiation output from high specularity areas is lower than the radiation output from low contrast areas;
• means for detecting said radiation, passed by said means for converting received radiation, for generating a signal representative of said alternative areas of high specularity and low contrast with the strength of the signal representing the highly specular areas substantially diminished to eliminate detector component saturation;
• means for converting said signal in its secondary state representative of the high specularity and low contrast areas from an analog signal to a digital signal;
• means to return by inversion a value of said digital signal corresponding to said secondary state back to a value corresponding to said primary state in which the signal representing highly specular areas is stronger than the signal representing low contrast areas;
• means for determining, from said inverted signal, the width of the areas representative of said areas of high specularity and low contrast;
• and
• means for interpreting the dimensions representative of said areas of high specularity and low contrast in order to obtain the information contained therein.

An improved bar code reader system for reading bar codes having bar segments and space segments in which one of either bar segments or space segments are highly specular and the other are of low contrast where the width of the bar and space segments are representative of information for an item bar coded comprising:

• means for illuminating a bar code label on the item with radiation polarized in a first direction;
• means for receiving radiation in a primary state as it is reflected from said bar code wherein radiation received from the highly specular segments is polarized in the first direction and radiation received from the low contrast segments is depolarized, thereby creating a high radiation output for highly specular segments and a low radiation output for low contrast segments;
• means for converting received radiation to a secondary state by blocking radiation polarized in said first direction representative of said highly specular segments and allowing to pass other radiation representative of said low contrast segments, resulting in a radiation pattern wherein the radiation output from highly specular segments is lower than the radiation output from low contrast segments;
• means for detecting the radiation from said means for converting received radiation, for generating a bar code signal representative of said bar and space segments in a secondary state inverted with respect to said primary state with the signal representing the highly specular segments substantially reduced to eliminate detector component saturation;
• means for converting said signal in its secondary state representative of the bars and spaces from an analog signal to a digital signal;
• means to return by inversion a value of said digital signal corresponding to said secondary state back to a value corresponding to said primary state in which signal representing highly specular segments is stronger than the signal representing low contrast segments;
• and
• means, responsive to said bar code signal, for determining the width of said bar segments and space segments to decode said bar code.