Method of identifying objects provided with a code field containing a dot code, a device for identifying such a dot code, and a product provided with such a dot code

• US 4,745,269 A
• Filed: 05/12/1986
• Issued: 05/17/1988
• Est. Priority Date: 05/22/1985
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Van Gils, Willibrordus J.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US06/862,068
• Time in Patent Office: 736 Days
• Field of Search: 235/487, 235/454, 382/11
• US Class Current: 235/487
• CPC Class Codes: B07C 5/3412 according to a code applied to the object which indicates a property of the object, e.g. quality class, contents or incorrect indication sorting according to size measured by light-responsive means B07C5/10; sorting according to optical properties B07C5/342; for packages B65D79/02; for information carriers G06K7/00
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 19/06075 the marking containing means for error correction
• CPC Class Codes: G06K 2019/06262 with target- or other orientation-indicating feature

Abstract

For the purpose of identification, an object is provided with a code field containing a dot code. The code field possesses a certain degree of multiplicity of rotational symmetry (for example, 2, 3, 4, 6). The code field contains information dots from which its orientation can be detected. Redundancy is added which includes the orientation information, so that a certain degree of error correction is possible. By way of example, a suitable code is given for rotationally symmetric objects on which there is not enough space for a bar code.

Claims

1. A method for identifying an object provided with an identifying code comprising an array of dots shaped as a code field having a predetermined multiplicity of rotational symmetry, which multiplicity lies between two and six, said method comprising the steps of:

providing an identifying information having n bits together with m additional bits for indicating an actual orientation among said multiplicity;

encoding said identifying information and additional bits (n+m bits) into a code word that comprises of a plurality of code dot groups arranged within said array, the dot positions in a dot group having the same multiplicity of rotational symmetry as said array, such that mapping of said code word by rotating among said multiplicity will always produce an acceptable code word, said code furthermore possessing error correction capability for at least two bits;

applying the dots of said code word to an object according to said array;

picking up said dots from said object and reconstructing said code word without taking into account an actual mapping while invoking said error correction capability; and

by means of said additional m bits correcting for said mapping if present and delivering said identifying code to a user.

2. A method as claimed in claim 1 wherein said additional m bits are mapped on as many code bits of said code word as are independent of said identifying information.

3. Method as claimed in claims 1 or 2, characterized in that said code is formed from a quasi-cyclic code.

4. Method as claimed in claims 1 or 2, characterized in that said code is formed from a cyclic or shortened cyclic code.

5. A device for identifying an object which is provided with a dot code field, which field has a predetermined multiplicity of rotational symmetry from two to six and includes identification dots, predetermined orientation indicating dots which indicate an actual orientation within said multiplicity, and error protection dots, said dot code representing a code word which comprises a plurality of dot code groups arranged within said dot code field, the dot positions in a dot code group having the same multiplicity of rotational symmetry as said field such that mapping of said code by rotation among said multiplicity always produces an acceptable code word;

comprising;

manipulation means which manipulate said object between feed means and removal means;

pick-up means which sense dot information of a code field on said object during said manipulation;

first processing means which multiply said dot information, arranged as a channel word, by a parity check matrix of said code, at an arbitrary orientation within said multiplicity, to form a syndrome;

second processing means receiving an output of said first processing means, which detect possible bit errors of said code word on the basis of said syndrome and upon detecting a correctable bit error pattern, correct such pattern to produce a reconstructed channel word, and upon detecting an uncorrectable bit error pattern produce an uncorrectability signal;

detection means receiving an output from said second processing means which detect said orientation indicating dots in said reconstructed channel word, and on the basis of a position thereof, impose a shift on the identification dots which conforms them with a standard orientation within said multiplicity; and

output means receiving an output from said second processing means and said detection means which output either said uncorrectability signal, if present, or said identification dots which have been conformed to said standard orientation.

7. Device as claimed in claim 5, characterized in that said output means contain source decoding means.

6. An object provided with a machine readable and machine error correctable dot code field having a predetermined multiplicity of rotational symmetry which lies between two and six inclusive, said dot code field comprising identification dots, predetermined orientation indicating dots for indicating an actual orientation within said multiplicity, and error protection dots covering both said identification dots and said orientation indicating dots, said dot code representing a code word that comprises a plurality of dot code groups arranged within said dot code field, the dot positions in a dot code group having the same multiplicity of rotational symmetry as said field, such that mapping of said code among said multiplicity would always produce an acceptable code word, said code allowing for multiplying said dot information by a parity matrix of the code at an arbitrary orientation multiplicity to form a syndrome as a basis for detecting possible bit errors of said code words and in case of detecting a correctable bit error pattern, correcting such pattern for thereupon detecting said orientation indicating dots as a basis for imposing a shift on the identification dots to conform to a standard orientation within said multiplicity for outputting in said standard orientation to a user