Method and device for decoding a position-coding pattern
First Claim
1. A method of coding positions in two dimensions on a surface, comprising:
- coding positions along an x-axis using a first difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the first difference number sequence, each position along the x-axis being coded by one of said partial sequences,coding positions a long a y-axis using a second difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the second difference number sequence, each position along the y-axis being coded by one of said partial sequences,coding the numbers of the first difference number sequence by differences in circular shifts between instances of a first main number sequence running orthogonally to the first difference number sequence; and
coding the numbers of the second difference number sequence by differences in circular shifts between instances of a second main number sequence running orthogonally to the second difference sequence.
1 Assignment
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Accused Products
Abstract
In a method for position decoding, a position is calculated on the basis of information determined from a partial area, imaged by a sensor, of a position-coding pattern. If the position calculation fails, the information from the partial area recorded by the sensor is matched with information about how the position-coding pattern is designed in a plurality of matching partial areas, which each define a position in the position-coding pattern. The position of the positions defined by the matching partial areas, which according to the matching step is the most probable position in the position-coding pattern for the imaged partial area is accepted as the decoded position. A device and a computer program for carrying out the method are also described.
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Citations
42 Claims
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1. A method of coding positions in two dimensions on a surface, comprising:
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coding positions along an x-axis using a first difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the first difference number sequence, each position along the x-axis being coded by one of said partial sequences, coding positions a long a y-axis using a second difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the second difference number sequence, each position along the y-axis being coded by one of said partial sequences, coding the numbers of the first difference number sequence by differences in circular shifts between instances of a first main number sequence running orthogonally to the first difference number sequence; and coding the numbers of the second difference number sequence by differences in circular shifts between instances of a second main number sequence running orthogonally to the second difference sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. The method as claimed in 13, wherein at least one of the first and the second main number sequences has the property that each partial sequence of a second predetermined length has an unambiguously determined place within the main number sequence, but does not occur backwards in the main number sequence.
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16. The method as claimed in 13, wherein at least one of the first and the second main number sequences has the property that each partial sequence of a second predetermined length has an unambiguous place within the main number sequence, but does not occur inverted in the main number sequence.
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17. The method as claimed in 13, wherein at least one of the first and the second main number sequences has the property that each partial sequence of a second predetermined length has an unambiguously determined place within the main number sequence, but does not occur with one bit inverted in the main number sequence.
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18. A method for decoding a subset of a position code, which subset codes an x-coordinate and a y-coordinate for at least one point on a surface, comprising:
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receiving a digital representation of the subset of the position code, identifying, based on said digital representation, first partial sequences of instances of a first main number sequence which run perpendicularly to an x-axis of the position code and second partial sequences of instances of a second main number sequence which run perpendicularly to a y-axis of the position code, determining, based on the first partial sequences, first differences in circular shifts between instances of the first main number sequence, said first differences constituting a partial sequence of a first difference number sequence, which defines the x-axis and has the property that any partial sequence of predetermined length in the first difference number sequence has an unambiguously determined place within the first difference number sequence and codes an x-coordinate; determining the x-coordinate for said at least one point using the partial sequence of the first difference number sequence; determining, based on the second partial sequences, second differences in circular shifts between instances of the second main number sequence, said second differences constituting a partial sequence of a second difference number sequence, which defines the y-axis and has the property that any partial sequence of predetermined length in the second difference number sequence has an unambiguously determined place within the second difference number sequence and codes a y-coordinate; and determining the y-coordinate for said at least one point using the partial sequence of the second difference number sequence. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 41)
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29. A device for decoding a subset of a position'"'"'code, which subset codes an x-coordinate and a y-coordinate for at least one point on a surface, comprising a processor configured to identify, based on a digital representation of the position code, first partial sequences of instances of a first cyclic main number sequence which run perpendicular to an x-axis of the position code and second partial sequences of instances of a second cyclic main number sequence which run perpendicularly to a y-axis of the position code;
- to determine, based on the first partial sequences, first differences in circular shifts between instances of the first cyclic main number sequence, said first differences constituting a partial sequence of a first difference number sequence, which defines the x-axis and has the property that any partial sequence of predetermined length in the first difference number sequence has an unambiguously determined place in the first difference number sequence and codes an x-coordinate;
to determine the x-coordinate for said at least one point using the partial sequence of the first difference number sequence;
to determine, based on the second partial sequences, second differences in circular shifts between instances of the second cyclic main number sequence, said second differences constituting a partial sequence of a second difference number sequence, which defines the y-axis and has the property that any partial sequence of predetermined length in the second difference number sequence has an unambiguously determined place in the second difference number sequence and codes a y-coordinate, and to determine the y-coordinate for said at least one point using the partial sequence of the second difference number sequence. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
- to determine, based on the first partial sequences, first differences in circular shifts between instances of the first cyclic main number sequence, said first differences constituting a partial sequence of a first difference number sequence, which defines the x-axis and has the property that any partial sequence of predetermined length in the first difference number sequence has an unambiguously determined place in the first difference number sequence and codes an x-coordinate;
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42. A product having a surface, the product being provided with a position code that codes positions on the surface in two dimensions, the positions along an x-axis being coded by a first difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the first difference number sequence, each position along the x-axis being coded by one of said partial sequences, the positions along a y-axis being coded by a second difference number sequence having the property that each partial sequence of a predetermined length has an unambiguously determined place within the second difference number sequence, each position along the y-axis being coded by one of said partial sequences, the numbers of the first difference number sequence being coded by differences in circular shifts between instances of a first main number sequence running orthogonally to the first difference number sequence;
- and the numbers of the second difference number sequence being coded by differences in circular shifts between instances of a second main number sequence running orthogonally to the second difference sequence.
Specification