US 5,514,858 AGranted

Method and apparatus for decoding unresolved complex multi-width bar code symbology profiles

AssigneeIntermec Corporation

InventorH. Sprague Ackley

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Abstract

A method and apparatus for decoding profiles which fail to resolve narrow elements in complex multi-width symbols, first begins by identifying which elements in the profile are resolved. Second, the environments surrounding each resolved element are examined. Third, several closure boundaries are determined, and the widths of resolved elements are determined at a selected threshold. The size of each resolved element is determined based on its measured width at a threshold selected based on the environment surrounding the resolved element. Fourth, the distances between the centers of the resolved elements are determined. Thereafter, an X-dimension is determined for 1-wide narrow elements unresolved in the profile. Based on the X-dimension and known center distances, a matrix is constructed for determining the number of narrow elements unresolved between two resolved elements. Based on the measured center distances, the resolved element widths and the matrix, all of the elements are identified in the profile and the profile is subsequently decoded.

Claims52

Dependent claims

A method of decoding a bar code symbol representing encoded information, the bar code symbol including a plurality of relatively spaced bars having at least first, second and third widths, and spaces between the bars having at least first, second and third widths, the second and third widths being greater than the first width, the method comprising the steps of:

receiving light reflected from the bar code symbol and producing an output signal therefrom that represents the reflectance of the bars and spaces comprising the bar code symbol;
receiving the output signal and producing a wide feature signal resolving the bars and spaces having the second and third widths, but the wide feature signal having unresolved portions that fail to resolve at least some of the bars and spaces having the first width;
receiving the wide feature signal and determining which of the bars and spaces are resolved by defining a first threshold and identifying a plurality of resolved portions in the wide feature signal that extend beyond the first threshold, each of the plurality of resolved portions corresponding to one of the resolved bars and spaces;
determining an environment for each of the plurality of resolved portions based on whether a selected resolved portion is between two other of the plurality of resolved portions, between two unresolved portions, or between a resolved and an unresolved portion in the wide feature signal;
defining at least a second threshold;
measuring a width for each of the plurality of portions at one of the first and second thresholds depending upon the environment of the selected resolved portion;
determining a narrow width of the bars and spaces having the first width based on the measured widths;
determining a number and location of the bars and spaces having the first width based on the determined narrow width and the measured widths;
and
determining the information encoded in the bar code symbol based on the determined number and location of bars and spaces having the first width and the measured width for each of the plurality of portions.

7 more elements

A method of decoding a machine-readable symbol representing encoded information, the symbol including a plurality of relatively spaced two-dimensional geometric shapes, the shapes and spaces between the shapes having sizes with at least first, second and third widths in at least one dimension, the second and third widths being greater than the first width, the shapes having a reflectivity less than a reflectivity of the spaces, the method comprising the steps of:

receiving light reflected from the symbol and producing an output signal therefrom that represents the reflectance of the shapes and spaces comprising the symbol;
receiving the output signal and producing a wide feature signal that resolves at least some of the shapes and spaces having the second and third widths, but which fails to resolve at least some of the shapes and spaces having the first width;
receiving the wide feature signal and determining which of the shapes and spaces are resolved by identifying a plurality of portions in the wide feature signal that correspond to the resolved shapes and spaces;
determining the size of each of the identified portions that correspond to the resolved shapes and spaces;
generating a lost element matrix in response to the wide feature signal and the sizes of the identified portions that correspond to the resolved shapes and spaces;
and
determining the information encoded in the symbol based on the lost element matrix and the determined size of each of the identified portions.

4 more elements

An apparatus for decoding a machine-readable symbol representing encoded information, the machine-readable symbol including a plurality of relatively spaced two-dimensional shapes, the geometric shapes and spaces between the shapes having sizes with first, second and third widths in at least one dimension, the second and third widths being greater than the first width, the apparatus comprising:

a sensor that receives light that is reflected from the machine-readable symbol and produces an output signal therefrom that represents the reflectance of the shapes and spaces comprising the symbol;
a receiver that receives the output signal and produces a large shape signal indicative of at least some of the shapes or spaces having the second or third widths, but failing to produce a signal indicative of at least some of the shapes and spaces having the first width;
and
a processor for processing the large shape signal and producing a signal indicative of the information encoded in the symbol, the processor (i) determining which of the shapes and spaces are resolved by identifying a plurality of portions in the large shape signal that each correspond to one of the resolved shapes and spaces, (ii) determining the size of the resolved shapes and spaces, (iii) generating a lost element matrix in response to the large shape signal and the size of the resolved shapes and spaces, and (iv) producing a signal indicative of the information encoded in the symbol based on the lost element matrix and the determined size of the resolved shapes and spaces.

1 more element

a sensor that receives light that is reflected from the machine-readable symbol and produces an output signal therefrom that represents the reflectance of the shapes and spaces comprising the symbol;
a receiver that receives the output signal and produces a large shape signal indicative of at least some of the shapes or spaces having the second or third widths, but failing to produce a signal indicative of at least some of the shapes and spaces having the first width;
a detection circuit that determines which of the shapes and spaces are resolved by identifying a plurality of portions in the large shape signal that each correspond to one of the resolved shapes and spaces;
a first measuring circuit that generates a distance signal indicating distances between each of the plurality of portions in the large shape signal, and that generates a size signal that indicates the size of the resolved shapes and spaces;
and
a decoding circuit that determines a number and location of the shapes and spaces having a first width by analyzing the distance signal and the width signal, and therefrom produces a signal indicative of the information encoded in the symbol.

3 more elements

Dependencies are inferred from the claim text.