Registers – Records
Reexamination Certificate
1999-05-12
2001-07-31
Lee, Michael G. (Department: 2876)
Registers
Records
C235S462080, C235S462090, C235S494000
Reexamination Certificate
active
06267296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to improvements on a two-dimensional code made up of a matrix of data cells carrying optically readable binary-coded information and an optical code reading method of reading such a two-dimensional code.
2. Background Art
U.S. Pat. No. 5,726,435 filed Mar. 10, 1998, assigned to the same assignee as that of this application, teaches a two-dimensional code used in inputting information into a computer.
Typical two-dimensional codes have a two-dimensional spread, as shown in FIG.
1
(
b
), which can carry a large amount of information in a narrow area as compared with a bar code, as shown in FIG.
1
(
a
), but the structure thereof is complex.
FIG. 2
shows one example of two-dimensional codes. The two-dimensional code
500
includes three location symbols
510
a
,
510
b
, and
510
c
and arrays of timing cells
520
a
and
520
b
. The location symbols
510
a
to
510
c
are used in locating the two-dimensional code
500
and each consist geometrically of a plurality of squares different in size. The arrays of timing cells
520
a
and
520
b
are each disposed between adjacent two of the location symbols
510
a
to
510
c
and consist of a plurality of white and black cells arranged in a reference pattern that are used as indices of data cells arranged in a data field
530
.
The two-dimensional code
500
is made up of a square matrix of n×n cells. Each of the location symbols
510
a
to
510
c
consists of a frame-like black square
512
formed with four sides each consisting of 7 cells, a frame-like white square
514
formed with four sides each consisting of 5 cells, and a black square
516
consisting of 3×3 cells formed on the central portion of the white square
514
.
When each of the location symbols
510
a
to
510
c
is scanned through an optical reader along any line passing through the center thereof, an optical signal pattern which has a brightness component ratio of black:white:black:white:black=1:1:3:1:1 is detected. Thus, when an optical signal pattern having that brightness component ratio is detected during scanning of the two-dimensional code
500
, it may be determined as a candidate pattern for any one of the location symbols
510
a
to
510
c
. Specifically, when three optical signal patterns each having a brightness component ratio of 1:1:3:1:1 are detected, it may be determined that the two-dimensional code
500
lies on a square area defined by the three optical signal patterns.
The data field
530
consists of data cells (not shown for the brevity of illustration) each formed with a black or white square indicating logical 0 or 1 of a binary-coded data. Two-dimensional coordinates of each data cell are determined in a known algorithm by using the centers of the location symbols
510
a
to
510
c
and the timing cells
520
a
and
520
b
as indices of the coordinates.
Usually, the size of each cell of such a two-dimensional code is required to be adjusted to individual uses. For example, optically reading a two-dimensional code printed on a label attached to an article being conveyed at high speeds requires increasing the size of each cell. However, for a two-dimensional code printed on an article being conveyed at low speeds or resting, the size of each cell may be small.
For instance, sorting a large number of articles automatically, may be achieved by transporting the articles at high speeds and optically reading two-dimensional codes printed thereon. In contrast, an operator may sort the articles manually by reading the two-dimensional codes using a hand-held optical reader. In this case, it is advisable that the two-dimensional code be made up of the smallest possible cells to reduce the overall size thereof.
In order to meet the above two requirements, it is necessary to make two-dimensional codes of two sizes. This, however, consumes much time of the operator in preparing and attaching two-dimensional code-printed labels to the articles. The two-dimensional code may alternatively be made which consists of two sections: one carrying data to be read out during transportation of the articles at high speeds, and the second carrying data to be read out during transportation of the articles at low speeds. However, the size of each cell needs to be fitted for the high speed transportation, thus resulting in an increased overall size of the two-dimensional codes. This also requires a large-sized optical reader.
SUMMARY OF THE INVENTION
It is therefore a principal object of the present invention to avoid the disadvantages of the prior art.
It is another object of the present invention to provide a simple and small-sized structure of a two-dimensional code containing two or more information codes formed with optical patterns made up of matrixes of cells different in size from each other which are suitable for being read under different conditions, respectively.
It is a further object of the present invention to provide a method of reading a two-dimensional code containing two or more information codes formed with optical patterns made up of matrixes of cells different in size from each other.
According to one aspect of the invention, there is provided a two-dimensional code which comprises: (a) a matrix of cells arranged in a given optically readable pattern which carries information; (b) at least two location symbols arranged at given locations in the matrix, each of the location symbols being made up of a given number of the cells arranged in a pattern to carry location data for specifying a location of the two-dimensional code; and (c) a data field defined in the matrix, including a first and a second data region which carry a first and a second information element, respectively. The first data region is made up of a given number of the cells each having a size identical with that of the cells of the location symbols and defined between the location symbols. The second data region is made up of a given number of the cells each having a size smaller than that of the cells in the first data region.
In the preferred mode of the invention, the second data region includes a plurality of sections which are made up of given numbers of the cells having different sizes, respectively, and which carry information elements, respectively.
The first information element is represented by a code that is of a type specified by the location symbols. The second information element is represented by a code that is of a type different from that of the first information element.
The second data region includes a plurality of sections which are made up of given numbers of the cells having different sizes, respectively, and which carry a plurality of different information elements, respectively, that are represented by codes different in type from each other and the first information element.
A format code is further provided which is arranged in a preselected positional relation to the location symbols and which indicates a format of the two-dimensional code.
The format code is made up of a given number of the cells arranged in a preselected optical pattern.
The format code carries data to specify at least one of a location of each of the first and second data regions, a type of code used in each of the first and second data regions, and a size of the cells in each of the first and second data regions.
The format code may alternatively hold classification information and version information. The classification information represents one of preselected combinations of locations of the first and second data regions, types of code used in the first and second data regions, and sizes of the cells in the first and second data regions. The version information specifies a geometrical pattern of the first data region as a function of a difference in cell size between the first and second data regions.
The format code may be arranged adjacent one of the location symbols.
An auxiliary symbol is further provided which is used in determining locations of the cells in
Ooshima Tadao
Tachi Ryosuke
Cyr Daniel St.
Denso Corporation
Lee Michael G.
Pillsbury & Winthrop LLP
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