US 5,304,786 A · High density two-dimensional bar code symbol

A method of generating a signal representative of information encoded in a machine-readable label,

(A) said machine-readable label including at least two rows of codewords, one row adjacent to and beneath another
(B) each said codeword representing at least one information-bearing character and being selected from among a set of detectable mark/space patterns,
(C) each said mark/space pattern having a determinable discriminator function value and comprising a pattern of marks and spaces, each said mark and space being representative of one of a plurality of different states,
(D) each said row having codewords selected from one of a plurality of subsets of said mark/space patterns, each said subset comprising mark/space patterns having discriminator function values that are mutually exclusive of discriminator values corresponding to the mark/space patterns comprising any other subset, said method including the steps of:
(a) scanning the codewords;
(b) computing the discriminator function value for each of the scanned codewords;
(c) determining, from the value of the computed discriminator function, the row containing each of the scanned codewords;
(d) decoding each of the scanned codewords to obtain a plurality of corresponding symbolic values;
and
(e) generating a signal representative of the presence of each of said corresponding symbolic values in the determined row.

7 more elements

A method of generating a signal representative of information encoded in a machine-readable label,

(A) said machine-readable label including first, second, and third rows of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns,
(B) each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states,
(C) each said mark and space having a width x.sub.i of an integral multiple of a basic width unit,
(D) each of said first, second, and third subsets including only codewords X matching all of the following criteria:
(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword X in the respective first, second, and third subsets is equal to 0, 3, or 6, respectively, (ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and (iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, said method including the steps of:
(a) scanning said mark/space patterns within said machine-readable label and generating an electronic image of each of said scanned mark/space patterns;
(b) determining whether each of said scanned mark/space patterns is a codeword;
(c) if any of said scanned mark/space patterns is a codeword, then classifying each of the codewords as a member of one of the first, second, or third subsets;
(d) decoding each of the codewords in the corresponding classified subset;
and
(e) generating a signal uniquely representing the codewords.

8 more elements

A method of generating a signal representative of information encoded in a machine-readable label,

(A) said machine-readable label including first, second, and third rows of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns,
(B) each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states,
(C) each said mark and space having a width x.sub.i of an integral multiple of a basic width unit,
(D) each of said first, second, and third subsets including only codewords X matching all of the following criteria:
(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword X in the respective first, second, and third subsets is equal to 0, 3, or 6, respectively, (ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and (iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, said method including the steps of:
(a) scanning said mark/space patterns within said machine-readable label and generating an electronic image of each of said scanned mark/space patterns;
(b) computing for each of the scanned mark/space patterns a t-sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the number of marks and spaces in a scanned mark/space pattern;
(c) computing the discriminator functions of each of the scanned mark/space patterns;
(d) if the computed t-sequence and the computed discriminator function for any of the scanned mark/space patterns fail to satisfy the criteria for said first, second, and third subsets, then indicating that each said failed mark/space pattern is not a codeword;
(e) if any of said scanned mark/space patterns is a codeword, then classifying each of the codewords as a member of one of the first, second, or third subsets;
(f) according to the classified subset, performing a first level of decoding each of the codewords including obtaining from one of three lookup tables in a first memory, the three tables respectively representing the first, second, and third subsets, a plurality of index numbers uniquely corresponding to the computed t-sequences;
(g) performing a second level of decoding the codewords including:
(1) converting each said index number into a two-digit number in base 30, the first digit of said two-digit number being a high value and the second digit being a low value;
(2) for each of the high values and the low values in succession, (i) determining, from the state of a decoding-mode variable stored in a second memory, which of a plurality of decoding modes is a currently active decoding mode, (ii) determining a symbol character associated with the high value or low value from a lookup table in said second memory associated with the active mode, and (iii) if the symbol character is a shift character, changing to a specified new current decoding mode and changing the state of the decoding-mode variable to correspond to the new decoding mode;
and
(h) generating a signal uniquely representing the codewords.

13 more elements

A method of generating a signal representative of information encoded in a machine-readable label,

(A) said machine-readable label including first, second, and third rows each comprising a plurality of codewords and at least one control word,
(B) each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns,
(C) each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states,
(D) each said mark and space having a width x.sub.i of an integral multiple of a basic width unit,
(E) each of said first, second, and third subsets including only codewords X matching all of the following criteria:
(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword X in the respective first, second, and third subsets is equal to 0, 3, or 6, respectively, (ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and (iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units,
(F) each said row including a checksum codeword representing a checksum function of the other codewords in the row, the checksum function being a function of unique respective values of each codeword in the row, said method including the steps of:
(a) scanning said mark/space patterns within a row and generating an electronic image of each of said scanned mark/space patterns;
(b) computing for each of the scanned mark/space patterns a t-sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the number of marks and spaces in a scanned mark/space pattern;
(c) computing the discriminator function of each of the scanned mark/space patterns;
(d) if the computed t-sequence and the computed discriminator function for any of the scanned mark/space patterns fail to satisfy the criteria for said first, second, and third subsets, then indicating that each said failed mark/space pattern is not a codeword;
(e) if any of the scanned mark/space patterns is a codeword, then classifying each of the codewords as a member of one of the first, second, or third subsets;
(f) according to the classified subset, performing a first level of decoding each of the codewords including obtaining from one of three lookup tables in a first memory, the three tables respectively representing the first, second, and third subsets, a plurality of initial index numbers uniquely corresponding to the computed t-sequences;
(g) storing said initial index numbers for each of the codewords in corresponding storage locations in an initial decoding array DA in a second memory;
(h) if an initial index number has been stored in the initial decoding array DA for all codewords in each of said rows, then computing checksum functions of the codewords represented in the initial decoding array DA;
(i) if any of the computed checksum functions does not match the checksum codeword for the respective row, then indicating an error;
(j) if a computed checksum function does match the checksum codeword for the row, then performing a second level of decoding the codewords including (1) converting each said initial index number into a two-digit number in base 30, the first digit of said two-digit number being a high value and the second digit being a low value, (2) for each of the high values and the low values in succession, (i) determining, from the state of a decoding-mode variable stored in a third memory, which of a plurality of decoding modes is a currently active decoding mode, (ii) determining a symbol character associated with the high value or low value from a lookup table in said third memory associated with the active mode, and (iii) if the symbol character is a shift character, changing to a specified new current decoding mode and changing the state of the decoding-mode variable to correspond to the new decoding mode;
and
(k) generating a signal uniquely representing the codewords.

16 more elements

A method of scanning and decoding a series of patterns representative of information encoded in a machine-readable label,

(A) said machine-readable label including first, second, and third rows each comprising a plurality of codewords and at least one control word,
(B) each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns,
(C) each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states,
(D) each said mark and space having a width x.sub.i of an integral multiple of a basic width unit,
(E) each of said first, second, and third subsets including only codewords X matching all of the following criteria:
(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword X in the respective first, second, and third subsets is equal to 0, 3, or 6, respectively, (ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and (iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units,
(F) each said row including a row checksum codeword representing a checksum function of the other codewords in the row, the checksum function being a function of unique respective values of each codeword in the row,
(G) the machine-readable label including a sequence of one or more codewords representing a structure checksum for the machine-readable label, said method including the steps of:
(a) scanning a mark/space pattern within a row and generating an electronic image of said scanned mark/space pattern;
(b) computing a t-sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the number of marks and spaces in the scanned mark/space pattern;
(c) computing the discriminator function of the scanned mark/space pattern;
and
(d) if the computed t-sequence and the computed discriminator function fail to satisfy the criteria for said first, second, and third subsets, then indicating that the scanned mark/space pattern is not a codeword;
(e) if the scanned mark/space pattern is a codeword, then classifying the codeword as a member of one of the first, second, or third subsets;
(f) according to the classified subset, performing a first level of decoding the codeword including obtaining from one of three lookup tables in a first memory, the three tables corresponding to the first, second, and third subsets, an initial index number uniquely corresponding to the computed t-sequence;
(g) storing said initial index number for the codeword in a corresponding storage location in an initial decoding array DA in a second memory;
(h) repeatedly performing steps (a) through (g) until an initial index number has been stored in the initial decoding array DA for (i) each of the row checksum codewords for each said row and the structure checksum codeword sequence, and (ii) all but at most two of all codewords in all rows of the machine-readable label;
(i) if an initial index number has not been stored for an unknown codeword in any of said rows, then computing an initial index number for each said unknown codeword as a function of one or both of the initial index numbers corresponding to the respective row checksum codeword and the structure checksum codeword sequence;
(j) if an initial index number has been stored in the initial decoding array DA for all codewords in any of said rows, then computing the respective checksum function of the codewords represented in the initial decoding array DA for each said row;
(k) if the computed checksum function does not match the row checksum codeword for any of said rows, then indicating an error for each unmatched checksum function.

17 more elements

A method for generating a signal produced by scanning a machine-readable label that includes a plurality of codewords organized into at least two adjacent rows, each said codeword representing at least one human-recognizable symbol and no codeword in any one row being identical to any codeword in an adjacent row, said method including the steps of:

(a) scanning said label to detect said codewords;
(b) determining a detectable characteristic for each said scanned codeword;
(c) computing a unique index number for each said scanned codeword as a function of said detectable characteristic;
and
(d) processing each of the index numbers to generate a signal representative of the at least one human-recognizable symbol.

2 more elements

An apparatus for generating a signal representative of information encoded in a machine-readable label, said machine-readable label including first, second, and third rows of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from first, second, and third subsets of detectable mark/space patterns, each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states, each said mark and space having a width x.sub.i of an integral multiple of a basic width unit, each of said first, second, and third subsets including only codewords X matching all of the following criteria:

(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword in the respective first, second and third subsets is equal to 0, 3, or 6, respectively,
(ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and
(iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, the apparatus comprising:
(a) means for scanning said mark/space patterns within said machine-readable label and for generating an electronic image of each of said scanned mark/space patterns;
(b) means for determining whether each of said scanned mark/space patterns is a codeword;
(c) means, coupled to said determining means, for classifying each of the codewords as a member of one of the first, second, or third subsets;
(d) means for decoding in the classified subset each of the codewords;
and
(e) means for generating a signal uniquely representing the codewords.

6 more elements

An apparatus for generating a signal representative of information encoded in a machine-readable label, said machine-readable label including first, second, and third rows of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from first, second, and third subsets of detectable mark/space patterns, each said mark/space pattern comprising a fixed width pattern of at least eight marks and spaces of varying widths representing on states and off states, each said mark and space having a width x.sub.i of an integral multiple of a basic width unit, each of said first, second, and third subsets including only codewords X matching all of the following criteria:

(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword in the respective first, second and third subsets is equal to 0, 3, or 6, respectively,
(ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and
(iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, the apparatus comprising:
(a) means for scanning said mark/space patterns within said machine-readable label and for generating an electronic image of each of said scanned mark/space patterns;
(b) first means for computing, from each of the scanned mark/space patterns, a t-sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the number of marks and spaces in each of the scanned mark/space patterns;
(c) second means for computing the discriminator function of each of the scanned mark/space patterns;
(d) means, coupled to the first and second computing means, for indicating that any of the scanned mark/space patterns is not a codeword, if the computed t-sequence and the computed discriminator function fail to satisfy the criteria for said first, second, and third subsets;
(e) means, coupled to said indicating means, for classifying each of the codewords as a member of one of the first, second, or third subsets;
(f) means, coupled to said classifying means, for performing a first level of decoding each of the codewords including obtaining from one of three lookup tables in a first memory, the three tables corresponding to the first, second, and third subsets, a plurality of index numbers uniquely corresponding to the computed t-sequences from the first computing means;
(g) means for performing a second level of decoding the codewords including:
(1) means for converting each said index number into a two-digit number in base 30, the first digit of said two-digit number being a high value and the second digit being a low value,
(2) for each of the high values and the low values, (i) first means for determining, from the state of a decoding-mode variable stored in a second memory, which of a plurality of decoding modes is a currently active decoding mode, (ii) second means for determining, a symbol character associated with the high value or low value from a lookup table in said second memory associated with the active mode, and (iii) means, coupled to said second determining means, for changing to a specified new current decoding mode, and for changing the state of the decoding-mode variable to correspond to the new decoding mode, if said symbol character is a shift character;
and
(h) means for generating a signal uniquely representing the codewords.

11 more elements

An apparatus for generating a signal representative of information encoded in a machine-readable label, said machine-readable label including first, second, and third rows each comprising a plurality of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns, each said mark/space pattern comprising a fixed-width pattern of at least eight marks and spaces of varying widths representing on states and off states, each said mark and space having a width x.sub.i of an integral multiple of a basic width unit, each of said first, second, and third subsets including only codewords X matching all of the following criteria:

(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword in the respective first, second and third subsets is equal to 0, 3, or 6, respectively,
(ii) all t-sequences t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and
(iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, each said row including a checksum codeword representing a checksum function of the other codewords in the row, the checksum function being a function of unique respective values of each codeword in the row, the apparatus comprising:
(a) means for scanning each of said mark/space patterns within said machine-readable label and for generating an electronic image of each of said scanned mark/space patterns;
(b) first means for computing, for each of the scanned mark/space patterns, a t-sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the number of marks and spaces in each of the scanned mark/space patterns;
(c) second means for computing the discriminator function of each of the scanned mark/space patterns;
(d) means, coupled to the first and second computing means, for indicating that any of the scanned mark/space patterns is not a codeword, if the computed t-sequence and the computed x-sequence fail to satisfy the criteria for said first, second, and third subsets;
(e) means, coupled to said indicating means, for classifying each of the codewords as a member of one of the first, second, or third subsets;
(f) means, coupled to said classifying means, for performing a first level of decoding the codewords including obtaining from one of three lookup tables in a first memory, the three tables corresponding to the first, second, and third subsets, a plurality of initial index numbers uniquely corresponding to the computed t-sequences from the first computing means;
(g) means for storing said initial index numbers for the codewords in a corresponding storage location in an initial decoding array DA in a second memory;
(h) third means for computing checksum functions of the codewords represented in the initial decoding array DA if an initial index number has been stored in the initial decoding array DA for all codewords in each of said rows;
(i) second means for indicating an error if any of the computed checksum functions does not match the checksum codeword for the respective row;
(j) means for performing a second level of decoding the codewords, if a computed checksum function does match the checksum codeword for the row, including:
(1) means for converting each said initial index number into a two-digit number in base 30, the first digit of said two-digit number being a high value and the second digit being a low value,
(2) first means for determining, for each of the high values and the low values, from the state of a decoding-mode variable stored in a third memory, which of a plurality of decoding modes is a currently active decoding mode,
(3) second means for determining, for each of the high values and the low values, a symbol character associated with the high value or low value from a lookup table in said third memory associated with the active mode, and
(4) means, coupled to said second determining means, for changing, for each of the high values and low values, to a specified new current decoding mode and changing the state of the decoding-mode variable to correspond to the new decoding mode if said symbol character is a shift character;
and
(k) means for generating a signal uniquely representing the codewords.

16 more elements

An apparatus for scanning and decoding a series of patterns representative of information encoded in a machine-readable label, said machine-readable label including first, second, and third rows each comprising a plurality of codewords and at least one control word, each said codeword representing at least one information-bearing character and being selected from among first, second, and third subsets of detectable mark/space patterns, each said mark/space pattern comprising a fixed-width pattern of marks and spaces of varying widths representing on states and off states, each said mark and space having a width x.sub.i of an integral multiple of a basic width unit, each of said first, second, and third subsets including only codewords X matching all of the following criteria:

(i) a discriminator function f(X)=(x.sub.1 -x.sub.3 +x.sub.5 -x.sub.7) mod 9 of each codeword in the respective first, second and third subsets is equal to 0, 3, or 6, respectively,
(ii) all t-functions t.sub.i =x.sub.i +x.sub.i+1 of each codeword X are not greater than 9 basic width units, and
(iii) each codeword X includes only marks and spaces whose widths are not greater than 6 basic width units, each said row including row checksum a codeword representing a checksum function of the other codewords in the row, the checksum function being a function of unique respective values of each codeword in the row, the machine-readable label including a sequence of one or more codewords representing a structure checksum for the machine-readable label, the apparatus comprising:
(a) means for scanning each of said mark/space patterns within said machine-readable label and for generating an electronic image of each of said scanned mark/space patterns;
(b) first means for computing, for each of the scanned mark/space patterns, a t-sequence of N-1 digits whose i.sup.th digit is t.sub.1, where N is the number of marks and spaces in each of the scanned mark/space patterns;
(c) second means for computing the discriminator function of each of the scanned mark/space patterns;
and
(d) means, coupled to the first and second computing means, for indicating that each of the scanned mark/space patterns is not a codeword, if the computed t-sequence and the computed discriminator function fail to satisfy the criteria for said first, second, and third subsets;
(e) means, coupled to the indicating means, for classifying each of the codewords as a member of one of the first, second, or third subsets, if the scanned mark/space pattern is a codeword;
(f) means, coupled to said classifying means, for performing a first level of decoding the codewords including obtaining from one of three lookup tables in a first memory, the three tables corresponding to the first, second, and third subsets, a plurality of initial index numbers uniquely corresponding to the computed t-sequences from the first computing means;
(g) means for storing each of said initial index numbers for each of the codewords in a corresponding storage location in an initial decoding array DA in a second memory;
(h) third means for computing an initial index number for each codeword for which an initial index number has not been stored in the initial decoding array DA;
(i) fourth means for computing the checksum function of the codewords represented in the decoding array DA for any of said rows in which an initial index number has been stored in the initial decoding array DA for all codewords in a row;
and
(j) second means for indicating an error for any of said rows in which the computed checksum function does not match the row checksum codeword.

12 more elements

An apparatus for generating a signal produced by scanning a machine-readable label, said machine readable label including a plurality of codewords organized into at least two adjacent rows, each said codeword representing at least one human-recognizable symbol and no codeword in any one row being identical to any codeword in an adjacent row, the apparatus comprising:

(a) means for scanning said label to detect said codewords;
(b) first decoding means for determining a detectable characteristic for each said scanned codeword;
(c) second decoding means for computing a unique index number for each said scanned codeword as a function of said detectable characteristic;
and
(d) means for processing each of the index numbers to generate a signal representative of said at least one human-recognizable symbol.

2 more elements

A method of reading a machine-readable symbol, the symbol including a plurality of individual codewords and at least one control word, each codeword and control word having a detectable mark/space pattern, the codewords, when taken in sequence, together defining an encoded version of data to be decoded, the mark/space pattern of each codeword having a detectable characteristic representative of information relating to a position of each said codeword within said sequence, the method comprising the steps, executed using a machine, of:

(a) scanning and reading the codewords;
(b) calculating, for each codeword X, a value of a discriminator function f(X) dependent upon the detectable characteristic;
(c) calculating a t-sequence for each said codeword X, the t-sequence being defined as a sequence of N-1 digits whose i.sup.th digit is t.sub.i, where N is the total number of marks and spaces in a mark/space pattern, each mark and space being a measured distance from one another and having a leading edge and a trailing edge, and t.sub.i equals a measured distance between the leading edge of the i.sup.th mark and the leading edge of the following mark in a mark/space pattern, or the leading edge of the i.sup.th space and the leading edge of the following space in a mark/space pattern;
and
(d) decoding each said codeword X as a function of the respective t-sequence and discriminator function f(X) and outputting a decoded version of said data.

2 more elements

High density two-dimensional bar code symbol

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High density two-dimensional bar code symbol

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Abstract

Claims70