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 6,729,542 B2
• Filed: 08/10/2001
• Issued: 05/04/2004
• Est. Priority Date: 12/27/1994
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Iwai, Toshiyuki, Aoki, Atsushi, Esashi, Masahiro, Yamaguchi, Norimasa, Kaminokado, Tsukasa, Niwamoto, Hiroaki
• Primary Examiner(s): TREMBLAY, MARK STEPHEN
• Application Number:
  US09/927,867
• Publication Number:
  US 20020027165A1
• Time in Patent Office: 998 Days
• Field of Search: 235/456, 235/487, 235/494, 235/462.08, 235/462.09
• US Class Current: 235/462.08
• 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 cells corresponding to bits are virtually set in a matrix form, each cell 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 cells 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 decoding method for decoding information recorded on a digital information recording carrier comprising:

a planar recording surface having an information recording area, said information recording area defining a plurality of cells arranged in matrix form,

each said cell being provided with an optically recognizable mark such that said cells together form an optically readable, two-dimensional pattern filling said information recording area;

said two-dimensional pattern comprising first portions wherein said cells respectively correspond to bits of digital information and second portions wherein said cells correspond to specific patterns that are spaced from each other, each said specific pattern consisting of a plurality of cells which are linked together and which are given optically recognizable marks in a respective pre-selected pattern, said specific patterns including a predetermined pattern which occupies a region in an inner portion of said information recording area spaced from the perimeter of said information recording area, said predetermined pattern including at least one central cell representing a first value and a plurality of contiguous cells representing a second value and at least partially surrounding said central cell;

said first portions of said information recording area occupy all regions of said information recording area other than the regions occupied by said specific patterns; and

the cells which make up the predetermined pattern are the same size and shape as the cells which make up the first portions of said information recording area;

the digital information decoding method comprising the steps of;

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

calculating positions of arbitrary cells corresponding to bits of digital information by a proportional allocation technique, based on the positions of four specific patterns out of all of the searched specific patterns, said four specific patterns being placed on two given rows and two given columns of said matrix;

reading the bits of digital information corresponding to each cell located at a calculated position; and

reproducing the digital information recorded on the recording surface based on the read bits of digital information.

2. The digital information recording method according to claim 1, wherein said cells each have a shape of the same size, wherein each specific pattern is composed of a central closed area with the shape of a square and a loop portion surrounding the central closed area entirely, wherein said central closed area consists of four cells each provided with a light as an optically recognizable mark and said loop portion consists of twelve cells 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 of a search for the central closed area of a specific pattern, to decide whether or not 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 the size, width, and height of the region are within certain ranges, respectively, to confirm that the region is the central closed area.

3. The digital information decoding method according to claim 1, wherein each of said cells has a shape of a square of the 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 cell provided with a dark as an optically recognizable mark, said first loop portion consists of eight cells each provided with a light as an optically recognizable mark, and said second loop portion consists of sixteen cells 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 a specific pattern to decide whether or not 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 the 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.

4. A digital information decoding apparatus for decoding digital information recorded on a digital information recording carrier comprising:

a planar recording surface having an information recording area, said information recording area defining a plurality of cells arranged in matrix form,

each said cell being provided with an optically recognizable mark such that said cells together form an optically readable, two-dimensional pattern filling said information recording area;

said two-dimensional pattern comprising first portions wherein said cells respectively correspond to bits of digital information and second portions wherein said cells correspond to specific patterns that are spaced from each other, each said specific pattern consisting of a plurality of cells which are linked together and which are given optically recognizable marks in a respective pre-selected pattern, said specific patterns including a predetermined pattern which occupies a region in an inner portion of said information recording area spaced from a perimeter of of said information recording area, said predetermined pattern including at least one central cell representing a first value and a plurality of contiguous cells representing a second value and at least partially surrounding said central cell;

said first portions of said information recording area occupy all regions of said information recording area other than the regions occupied by said specific patterns; and

the cells which make up the predetermined pattern are the same size and shape as the cells which make up the first portions of said information recording area;

reading means for reading said two-dimensional pattern recorded on said recording surface and outputting information representing said 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 the positions thereof, then calculate positions of arbitrary cells corresponding to bits of digital information 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 of said matrix, then read bits of digital information corresponding to each cell located at a calculated position, and then reproduce the digital information recorded on the recording surface based on the read bits of digital information; and

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