Browse Prior Art Database

Bar Code Symbol Recognition

IP.com Disclosure Number: IPCOM000050529D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 6 page(s) / 71K

Publishing Venue

IBM

Related People

Laurer, GJ: AUTHOR [+2]

Abstract

This article describes a process for recognizing different types of barcoded symbols (e.g., UPC-A, EAN-13, EAN-8, etc.) where common character coding is employed but the symbol types differ as to the number of characters, the parity patterns of those characters within the symbol and the number of segments.

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Bar Code Symbol Recognition

This article describes a process for recognizing different types of barcoded symbols (e.g., UPC-A, EAN-13, EAN-8, etc.) where common character coding is employed but the symbol types differ as to the number of characters, the parity patterns of those characters within the symbol and the number of segments.

There are many different types of bar-code readers today. In the most common of these, numeric data characters are represented by combinations of two light bars (spaces) alternating with two dark bars. The width of the individual bars and spaces uniquely defines each data character. Numeric data characters are always seven units wide, with individual bars or individual spaces occupying one to four contiguous units. Numeric data characters may have odd parity or even parity. Even parity means that the two bars in the character have a combined width of two or four units. Odd parity means that the two bars have a combined width of three or five units.

Numeric data characters are combined into segments which are limited by a guard character and a center character. Table 1 below is a parity code table which shows the character pattern and segment notations of the segments which make up different types of symbols. The specific bar-code structures for specific numeric data characters and for the guard and center characters can be found in material distributed by the UPC Council.

Table 2 below defines various types of symbols in terms of the arrangement of segments which are included within those symbols. Where two segments are connected by a "+" symbol, the segments share a common center character. For example, a version A symbol is defined as R + AR which, in accordance with Table 1, means that symbol contains from left to right: a guard character, six odd-parity data characters, a center character, six even-parity data characters, and a guard character. Where Table 2 shows segments separated by a space for a particular type of symbol, the spaced segments do not share center characters. PARITY DECODE TABLE

Segment Notation Parity Pattern n1 G E E O O C

n2 G O E E O C

n3 G E O O E C

n4 G E O E O C

n5 G O E O E C

n6 G O O E E C

8L G O O O O C

8R G E E E E C

G O O E O E E C

G O O E E O E C

G O O E E E O C

G O E O O E E C

N(X) G O E E O O E C

G O E E E O O C

G O E O E O E C

1

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G O E O E E O C

G O E E O E O C

G E E E O O O C

G E E O E O O C

G E E O O E O C

G E E O O O E C

E(X) G E O E E O O C

G E O O E E O C

G E O O O E E C

G E O E O E O C

G E O E O O E C

G E O O E O E C

A(L) G O O O O O O C

/A/R(D) G E E E E E E C

TABLE 1

SYMBOL TYPE SEGMENT ARRANGEMENT

Version A A(L) + A(R)

Version E E(X)

EAN-8 8L + 8R

EAN-13 N(X) + A(R)

Version D1 D n6 + 8L

Version D2 D + A n2 + 8R

Version D3 D + A(R)n3 n5 + 8R

Version D4 D + A(R)n5 + n1 n4 + 8R

Version D5 D + A(R)n4 + 8R n3 n6 + n1

TABLE 2

The flow charts and truth tables described below are used to select the correct symbol type on the basis of decoded segments w...