Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2001-12-20
2004-01-06
Lee, Michael G. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462010, C235S462150
Reexamination Certificate
active
06672510
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to bar codes. More specifically, the present invention is concerned with the use of bar codes for measurement.
BACKGROUND OF THE INVENTION
Bar codes are widely used for identifying and tracking objects. Their applications are numerous, including sorting and inventory management.
A bar code symbol typically includes a sequence of consecutive parallel bars and spaces of varying widths that are either printed directly onto the object or printed onto labels that are affixed to the object. The bar codes are generally read by a scanning light source, such as a laser, often in the form of a handheld device. The beam of light projected onto the bar code produces a spot that is moved by an oscillating motor to produce a line or a series of lines across the bars and spaces. A sensor detects the light reflected form the bar code and converts it into an electric signal to be interpreted (or decoded) by an electronic circuit or software.
Bar codes may have different structures, each requiring a different set of rules and definitions to be interpreted. Examples of such a structure include Universal Product Code (UPC), Code 39, Codabar, and Interleaved 2 of 5. For concision purposes, the “Interleaved 2 of 5” bar code structure will be referred to herein simply as “Interleaved”
The structure of an Interleaved bar code
10
is illustrated in FIG.
1
. “Interleaved” is a numbers-only bar code system that can only handle numbers having a even number of digits. This bar code system is said to be interleaved, because a first digit is encoded in the bars
12
, and a second digit is encoded in the spaces
14
. There are five bars
12
, two of which
12
′ are wide and five spaces
14
, two of which
14
′ are also wide. The interleaved 2 of 5 system allows the representation of numbers having an infinite number of digits, provided that there is a surface large enough to hold the symbols.
In the case of
FIG. 1
, the number
96
is provided as an example. The first digit
9
is represented by the bars
12
, and the second digit
6
is represented by the spaces
14
.
Bar codes, according to the “Interleaved” encoding system, include start and stop characters
16
and
18
as explained hereinbelow.
The use of the “Interleaved” structure is advantageous in many applications since it allows holding up to 18 digits per inch when printed using a 0.19 mm X dimension. As is well known in the art, the X-dimension is the width of the smallest element in a bar code symbol.
It is to be noted that, in the case of “Interleaved” symbols, the use of check digit is optional.
Since bar codes, in general, and the “Interleaved 2 of 5” system in particular, are believed to be well known in the art, they will not be described herein in further detail.
Most recent developments in bar code technology have aimed to increase the quantity and diversity of data supported by bar code symbols. However, new possibilities made possible by these new technologies remain in the context of sorting and inventory management.
Recently, a new application for bar code symbols has been in use as a measurement tool. Indeed, by aligning bar code symbols along an axis, and by predetermining positions corresponding to each bar code symbol, the scanning of a symbol may readily allow the retrieval of the coordinates of this position along the axis.
Turning now to
FIG. 2
of the appended drawings, a bar code ribbon
20
, according to the prior art, will now be described.
The bar code ribbon
20
comprises a plurality of bar code symbols
22
positioned in a column along the axis
24
. Although the example of
FIG. 2
is illustrated with symbols representing numbers using the “Interleaved 2 of 5” encoding system, other bar code systems can also be used. The numbers represented by each bar code symbol
22
have been provided in
FIG. 2
to the left of each symbol
22
.
To use the ribbon
20
for measuring positions on an object (not shown), a calibration of the ribbon
20
is first carried out. The calibration consists of measuring the distance from one end
26
of the ribbon
20
to each bar code symbol
20
, and by associating this distance to a corresponding symbol
20
.
In operation, by correctly positioning the bar code ribbon
20
on or near an object (not shown), positions on this object along the axis
24
may be readily determined using a conventional bar code scanner and an appropriate apparatus for decoding the symbols
20
.
Of course, the ribbon
20
has to be adequately positioned on or near the object and the height of the bar code symbols should be small enough to provide the precision required by the application. The ribbon
20
can then be seen as a ruler.
Although bar code symbols encoded by other systems may be used, the use of the “Interleaved 2 of 5” is advantageous, since it allows for the use of smaller bar code symbols when required by the application.
A major drawback in the use of a column of adjacent bar code symbols to measure the position on an object is that the smaller the height of the symbol is, the less the orientation of the bar code scanning beam has to deviate from the horizontal to cause an incorrect reading.
FIGS. 3 and 4
illustrate how an oblique scanning beam may cause an incorrect reading of a bar code symbol when there is at least one other bar code symbol adjacent to the one being scanned.
In
FIG. 3
, it is shown that a beam scanning between the symbols representing the numbers
09
and
19
on the ribbon
20
along the direction represented by line
28
may incorrectly yield the decoded number
49
.
In
FIG. 4
, it is shown that a beam scanning between the symbols representing the numbers
09
and
19
on the ribbon
20
along a direction opposite to the direction of line
28
in
FIG. 3
, as represented by line
30
, may in this case incorrectly yield the decoded number
89
. It is to be noted that, in some applications, the positions of the symbols representing the numbers
49
and
89
may be far enough from the actual scanning position to cause significant detrimental results.
A proposed solution to this problem is to use check digits on the symbols along with the encoded values. The use of check digits allows detection of incorrect readings resulting from a bad scan. However, a drawback of this solution is that it requires larger symbols, which, in some applications, may not be possible.
Of course, as illustrated in
FIG. 2
, the sequence of symbols may also be chosen so as to minimize the possibility or the impact of an incorrect reading, but, again, this may not be possible in some applications.
Another solution would be to provide the scanner with a means to ensure an adequate positioning relative to the symbols to scan. However, this would require either modifications to existing scanning technologies or scanning processes, which would not be universal, or a scanning method so complicated that it would cancel most of the advantages of the existing bar code scanning technology.
SUMMARY OF THE INVENTION
More specifically, in accordance with the present invention, there is provided a bar code arrangement for identifying positions along an axis, the arrangement comprising: a plurality of bar code symbols, each having start and stop end characters and encoded data therebetween; each symbol being positioned in a column along the axis and being so oriented that each bar of the symbols is parallel to the axis and that two consecutive bar code symbols have different orientations, one being rotated 180° relative to the other; whereby a particular position along the axis may be identified by scanning the bar code symbol corresponding to the particular position among the plurality of bar code symbols in the column; a symbol scan being considered successful when two different characters are found in the symbol scan.
According to second aspect of the invention, there is provided a bar code ribbon for identifying positions along an object, the ribbon comprising: two generally parallel longitudinal sides extending along an axis; two opposite faces
Koyama Kumiko C.
Lee Michael G.
Merchant & Gould P.C.
Scannabar (3193519 Canada Inc.)
LandOfFree
Bar code arrangement for identifying positions along an axis does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bar code arrangement for identifying positions along an axis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bar code arrangement for identifying positions along an axis will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3210948