Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1999-03-31
2002-03-19
Lee, Michael G. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462190
Reexamination Certificate
active
06357660
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bar code reading apparatus for decoding a character from bar code data read from a reflected light from a bar code expressing a character with bars having different widths.
2. Description of the Related Art
In recent years, the POS (Point of Sales) system is becoming increasingly popular so as to grasp the contents of sales of a product more quickly with less labor in retail shops such as convenience stores, department stores, and super markets. In such a POS system, there is placed a bar code reading apparatus for optically reading the bar code attached to a product expressing a character and decoding the character according to a result of reading operation.
There is sometimes a non-uniformity of bar widths in a bar code because of a difference in the printing precision, therefore there is a strong need in the bar code reading apparatus that it should execute high precision character decoding by not being affected by such a non-uniformity.
A bar code attached to a product (not shown), comprises a plurality of black bars and a plurality of white bars placed alternately, and expresses overall 20 types of characters from E(for Even)
0
to E
9
and O(for Odd)
0
to O
9
described later.
As the bar code described above, there are bar code symbols defined as those for JAN (Japan Article Number), WPC (World Product Code) commonly available all over the world, EAN (European Article Number) used in Europe, and UPC (Universal Product Code) used in the United States.
FIG. 6
is a top view showing an example of a bar code
10
. The bar code shown in this figure has, for instance, a black bar BB
1
, a white bar WB
1
, a black bar BB
2
, and a white bar WB
2
. Also the bar code
10
comprises a left block
11
expressing a product manufacturer code, a right block
12
expressing a product item code at the right side of the left block
11
with a center bar
13
therebetween, and a left guard bar
14
and a right guard bar
15
provided at the left edge of the left block
11
and at the right edge of the right block
12
, respectively.
As shown in
FIG. 7A
to
FIG. 7D
, one character in the bar code
10
comprises four bars (elements), namely a first black bar, a second white bar, a third black bar, and a fourth white bar arrayed from the right side to the left side of the figure, and the character length (width) C (an inter-edge distance from the first black bar to the fourth white bar) is assumed as 7 modules (the unit length is described as “module” herein).
The bar code
10
basically expresses 10 types of figures (characters) from “0” to “9” with combinations of a black bar width B
1
of the first black bar, a white bar width B
2
of the second white bar, a black bar width B
3
of the third black bar, and a white bar width B
4
, but as shown in
FIG. 8
, it is possible to express 20 types of characters with the same figures by introducing two types of combinations in which a total number of modules for black bars is regarded as an even number or an odd number.
Herein a bar code in which the total number of modules for black bars is an odd number is described as odd (simply described as O hereinafter) and a bar code in which the total number of modules for black bars is an even number is described as even (simply described as E hereinafter). In the case shown in
FIG. 8
, 10 types of characters in which a total number of modules for black bars indicating character O
0
to character O
9
is an odd number and 10 types of character in which a total number of modules for black bars indicating character E
0
to character E
9
is an even number, totally 20 types of characters are shown.
To describe by referring to the character O
0
and character E
0
as examples, the character O
0
from the right side to the left side in the figure consists of a first black bar (one module), a black white bar (one module), a third black bar (two modules), and a fourth white bar (three modules). Thus, in the character O
0
, the sum of the number of modules for the first black bar (=1 module) and for the third black bar (=2 modules) is three modules which is an odd number.
On the other hand, the character E
0
consists of, from the right side to the left side in the figure, a first black bar (three modules), a second white bar (two modules), a third black bar (one module), and a fourth white bar (one module). Thus, in the character E
0
, the sum of the number of modules for the first black bar (=3 modules) and for the third black bar (=1 module) is four modules which is an even number.
The character E
4
shown in
FIG. 7A
consists of, from the right side to the left side in the figure, a one module black bar having the black bar width B
1
, a one module white bar adjoining the black bar and having the white bar width B
2
, a three modules black bar adjoining the white bar and having the black bar width B
3
, and a two modules white bar adjoining the black bar and having the white bar width B
4
.
Herein, a sum of the black bar width B
1
and white bar width B
2
, namely the inter-edge distance between the first black bar and second white bar is called as delta distance T
1
, and in the example shown in the figure, the delta distance T
1
is two modules. Further, a sum of the white bar width B
2
and the black bar width B
3
, namely the inter-edge distance between the second white bar and the third black bar is called as delta distance T
2
, and in the example shown in the figure, this delta distance T
2
is four modules.
The delta distance T
1
, delta distance T
2
, black bar width B
1
, and black bar width B
3
are important parameters used to identify which of the characters O
0
to O
9
and characters E
0
to E
9
the character corresponds to.
Namely, as shown in
FIG. 8
, the delta distance T
1
in each of the characters O
0
to O
9
is different from the delta distance T
2
in each of the characters E
0
to E
9
, so that the character is identified from the delta distance T
1
and delta distance T
2
. In this operation for identifying a character, a first decoding table
100
of
FIG. 10
showing a relation between combination patterns of the delta distance T
1
and delta distance T
2
and characters is used.
It should be noted that, in the characters E
2
and E
8
, characters O
2
and O
8
, characters O
1
and O
7
, and characters E
1
and E
7
, the delta distance T
1
and delta distance T
2
in each of the combinations are identical to each other, therefore as shown in
FIG. 10
, and the character cannot be identified from the delta distance T
1
and delta distance T
2
.
To describe more specifically using the characters E
2
and character E
8
as examples, the delta distance T
1
is three modules and also the delta distance T
2
is three modules in both these characters, namely the two delta distances are equal to each other, so that to which of the characters E
2
and character E
8
the character to be identified corresponds to can not be identified only from the delta distance T
1
and delta distance T
2
.
By using the fact that a black bar width for the first black bar and that for the third black bar are different from each other in the characters E
2
and E
8
, character O
2
and O
8
, characters O
1
and O
7
, and characters E
1
and E
7
, it is possible to identify the character from both or either one of the black bar widths.
To describe more specifically using the characters E
2
and character E
8
shown in
FIG. 8
as examples, in the character E
2
, a black bar width of the first black bar is two modules, and a black bar width of the third black bar is two modules. On the other hand, in the character E
8
, a black bar width of the first black bar is one module, and a black bar width of the third black bar is one module, so that the black bar width in each bar of the character E
8
is different from that in each bar of the character E
2
. Therefore, it is possible to identify the characters E
2
and character E
8
from the black bar width of the first black bar and that of t
Iwaguchi Isao
Kawai Hiroaki
Watanabe Mitsuo
Armstrong Westerman & Hattori, LLP
Fureman Jared J.
Lee Michael G.
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