Method and apparatus for recording digital information in two-dimensional pattern, carrier of digital information recorded thereby, and a method and apparatus for decoding such digital information

• US 20020027165A1
• Filed: 08/10/2001
• Published: 03/07/2002
• Est. Priority Date: 12/27/1994
• Status: Active Grant

• Current Assignee: Atsushi Aoki, Hiroaki Niwamoto, Masahiro Esashi, Norimasa Yamaguchi, Toshiyuki Iwai, Tsukasa Kaminokado
• Original Assignee: Atsushi Aoki, Hiroaki Niwamoto, Masahiro Esashi, Norimasa Yamaguchi, Toshiyuki Iwai, Tsukasa Kaminokado
• Inventors: Esashi, Masahiro, Iwai, Toshiyuki, Aoki, Atsushi, Kaminokado, Tsukasa, Niwamoto, Hiroaki, Yamaguchi, Norimasa
• Granted Patent: US 6,729,542 B2
• Time in Patent Office: Days
• US Class Current: 235/494
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1417 2D bar codes

Abstract

A digital information recording carrier has a planar recording surface having an information recording area in which meshes corresponding to bits are virtually set in a matrix form, each mesh being provided with an optically recognizable mark corresponding to digital information so that the digital information is recorded in the information recording area as a two-dimensional pattern. The carrier also has specific patterns each consisting of a plurality of meshes which are linked together and which are given marks in a given pattern. Some of the specific patterns are placed in an inner portion apart from a perimeter of the information recording area.

Claims

1. A digital information recording carrier, comprising:

a planar recording surface having an information recording area in which meshes corresponding to bits are virtually set in a matrix form, each mesh being provided with an optically recognizable mark corresponding to digital information so that the digital information is recorded in the information recording area as a two-dimensional pattern; and

specific patterns each consisting of a plurality of meshes which are linked together and which are given optically recognizable marks in a given pattern, said specific patterns including a specific pattern which is placed in an inner portion apart from a perimeter of the information recording area.

2. The digital information recording carrier according to claim 1, wherein said specific patterns are dispersedly arranged all over the information recording area.

3. The digital information recording carrier according to claim 1, wherein said meshes each have a shape of a square of same size, wherein each specific pattern is composed of a central closed area with a shape of a square and a loop portion surrounding the central closed area entirely, and wherein said central closed area consists of four meshes each provided with a light as an optically recognizable mark and said loop portion consists of twelve meshes each provided with a dark as an optically recognizable mark.

4. The digital information recording carrier according to claim 1, wherein said meshes each have a shape of a square of same size, wherein each specific pattern is composed of a central portion with a shape of a square, a first loop portion surrounding the central portion entirely, and a second loop portion surrounding the first loop portion entirely, and wherein said central portion consists of a single mesh provided with a dark as an optically recognizable mark, said first loop portion consists of eight meshes each provided with a light as an optically recognizable mark, and said second loop portion consists of sixteen meshes each provided with a dark as an optically recognizable mark.

5. The digital information recording carrier according to claim 2, wherein said specific patterns are arranged with higher density in a peripheral part of the information recording area than in an interior of the information recording area.

6. The digital information recording carrier according to claim 2, wherein said specific patterns are arranged with higher density in an interior of the information recording area than in a peripheral part of the information recording area.

7. The digital information recording carrier according to claim 2, wherein said information recording area is a rectangular area having four corners and a specific pattern is placed at each corner.

8. The digital information recording carrier according to claim 7, wherein the specific patterns placed at the four corners are different from the specific patterns placed in the other portions of the information recording area.

9. The digital information recording carrier according to claim 7, wherein part of the specific patterns placed at the four corners are different from the rest thereof such that a set of the specific patterns placed at the four corners becomes asymmetrical with respect to a 90°

, 180°

, or 270°

rotation on the recording surface.

10. The digital information recording carrier according to claim 1, wherein said specific patterns have a light and a dark as the optically recognizable marks, and wherein a light/dark status of some of said specific patterns is inverse to that of the other specific patterns so as to make a contrast against nearby meshes in which digital information has been recorded.

13. A digital information decoding method for decoding information recorded on the digital information recording carrier according to claim 1, the digital information decoding method comprising the steps of:

searching the information recording area for the specific patterns to determine their positions;

calculating positions of arbitrary information-recorded meshes by a proportional allocation technique, based on positions of four specific patterns out of all the searched specific patterns, said four specific patterns being placed on two given rows and two given columns;

reading bit information of each mesh located at the calculated position; and

reproducing the digital information recorded on the recording surface based on the read bit information.

17. A digital information decoding apparatus for decoding digital information recorded on the digital information recording carrier according to claim 1, comprising:

reading means for reading the two-dimensional pattern recorded on the recording surface and outputting information representing the two-dimensional pattern;

information decoding means for reproducing the digital information recorded on the recording surface, wherein said information decoding means search inside of the two-dimensional pattern represented by the output information of the reading means for the specific patterns to determine positions thereof, then calculate positions of arbitrary information-recorded meshes by a proportional allocation technique based on the positions of four specific patterns out of all the searched specific patterns, said four specific patterns being placed on two given rows and two given columns, then read bit information of each mesh located at the calculated position, and then reproduce the digital information recorded on the recording surface based on the read bit information; and

output means for outputting the digital information reproduced by the information decoding means.

11. A digital information recording method, comprising the steps of:

virtually setting meshes corresponding to bits in a matrix form in an information recording area provided within a planar recording surface;

placing specific patterns at least in an interior of the information recording area apart from a perimeter of the information recording area, wherein each specific pattern consists of a plurality of meshes which are linked together and which are given optically recognizable marks in a given pattern; and

providing each of the meshes present in regions other than regions occupied by the specific patterns of the information recording area with an optically recognizable mark corresponding to digital information to be recorded so that the digital information is recorded in the information recording area as a two-dimensional pattern.

12. The digital information recording method according to claim 11, wherein each mark represents either a light or a dark, the method further comprising the steps of:

comparing light/dark statuses of meshes defining a perimeter of each specific pattern with light/dark statuses of information-recorded meshes which are immediately adjacent to the perimeter of the specific pattern; and

inverting, if the compared light/dark statuses are coincident with each other, the light/dark statuses of constituent meshes of the specific pattern such that the specific pattern is distinguished from the adjacent information-recorded meshes.

14. The digital information decoding method according to claim 13, wherein said meshes each have a shape of a square of same size, wherein each specific pattern is composed of a central closed area with a shape of a square and a loop portion surrounding the central closed area entirely, wherein said central closed area consists of four meshes each provided with a light as an optically recognizable mark and said loop portion consists of twelve meshes each provided with a dark as an optically recognizable mark, and wherein said step of searching the information recording area for the specific patterns comprises the sub-steps of:

checking the light/dark status of a reference position for a search for the central closed area of the specific pattern, to decide that the reference position is contained in the central closed area if the light/dark status of the reference position is a light; and

checking a region occupied by lights which are linked to each other, said reference position being included in said region, as to whether or not size, width, and height of the region are within certain ranges, respectively, to confirm that the region is the central closed area.

15. The digital information decoding method according to claim 13, wherein said meshes each have a shape of a square of same size, wherein each specific pattern is composed of a central portion with a shape of a square, a first loop portion surrounding the central portion entirely, and a second loop portion surrounding the first loop portion entirely, and wherein said central portion consists of a single mesh provided with a dark as a mark, said first loop portion consists of eight meshes each provided with a light as a mark, and said second loop portion consists of sixteen meshes each provided with a dark as a mark, and wherein said step of searching the information recording area for the specific patterns comprises the sub-steps of:

checking the light/dark status of a reference position for a search for the central closed area of the specific pattern, to decide that the reference position is contained in the central closed area if the light/dark status of the reference position is a dark;

checking a first dark region occupied by darks which are linked to each other, said reference position being included in said first dark region, as to whether or not size, width, and height of the first dark region are within certain ranges, respectively, to confirm that the first dark region is the central closed area; and

confirming, when a second dark region appears within a certain distance upward, downward, rightward or leftward from the first dark region after a light region has appeared and when a loop has been made around a boundary between the light region and the second dark region, that the light region is the first loop portion.

16. A digital information recording apparatus for recording digital information as a two-dimensional pattern in an information recording area provided within a planar recording surface, wherein meshes corresponding to bits are virtually set in a matrix form in the information recording area and the recording of digital information is executed by providing an optically recognizable mark corresponding to the digital information to each of the meshes, said digital information recording apparatus comprising:

input means for inputting digital information to be recorded into the digital information recording apparatus;

pattern generating means for generating a two-dimensional pattern to be printed onto the recording surface, by placing specific patterns inside of the information recording area apart from its perimeter, the specific patterns being each formed of a plurality of linked meshes provided with optically recognizable marks in a given pattern, and by placing the digital information in regions of the information recording area other than regions occupied by the specific patterns; and

printing means for printing the two-dimensional pattern generated by the pattern generating means onto the recording surface.