Position determination II—calculation

• US 6,674,427 B1
• Filed: 10/02/2000
• Issued: 01/06/2004
• Est. Priority Date: 10/01/1999
• Status: Expired due to Term

• Current Assignee: Anoto Group AB
• Original Assignee: Anoto Group AB
• Inventors: Edso, Tomas, Pettersson, Mats Petter
• Primary Examiner(s): Mengistu, Amare
• Application Number:
  US09/676,893
• Time in Patent Office: 1,191 Days
• Field of Search: 345/179, 345/18.01, 345/18.09, 345/19.01, 235/494, 235/380, 235/435, 382/306, 382/232
• US Class Current: 345/179
• CPC Class Codes: G06F 3/0321 by optically sensing the absolute position with respect to a regularly patterned surface forming a passive digitiser, e.g. pen optically detecting position indicative tags printed on a paper sheet constructional details of pen-shaped pointing devices G06F3/03545, G06F3/03542, G06F3/037
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06K 19/06018 one-dimensional coding
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• 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
• CPC Class Codes: G06K 7/1443 locating of the code in an image
• CPC Class Codes: G06K 7/1456 determining the orientation of the optical code with respect to the reader and correcting therefore
• CPC Class Codes: G06V 10/17 using hand-held instruments
• CPC Class Codes: G06V 10/19 by sensing codes defining pattern positions

Abstract

A method of providing a position code on a surface, which position code codes a plurality of positions on the surface. A cyclic number series is used, which has the characteristic that the position in the number series of each number sequence of a first predetermined length is determined unambiguously. The number series is printed out a plurality of times across the surface, different rotations of the first cyclic number series being used so that displacements arise between adjacent number series. The surface is divided into a plurality of code windows, which comprise at least three number series and have one number series overlapping one number series of adjacent code windows. The position of the code windows in the x-direction is coded by means of the displacements between the cyclic number series belonging to the code window. A second number series is used for coding in the y-direction. The invention also concerns a method and a device for determining the position, and a device and a computer program product for implementing the method.

Claims

1. A method of providing a position code on a surface, which position code codes a plurality of positions in a first direction on the surface, comprising the steps of

using a first cyclic number series, which has the characteristic that the position in the number series of each number sequence of a predetermined length is determined unambiguously,

printing out the first cyclic number series a plurality of times across the surface, different rotations of the first cyclic number series being used in such a way that predetermined displacements arise between adjacent number series,

wherein the step of printing out comprises

dividing the surface into a plurality of first code windows in the first direction, each of which comprises at least three first cyclic number series and has one number series overlapping one number series of adjacent first code windows, and using such rotations of the first cyclic number series when printing this out that the position of each first code window in the first direction is coded by means of the displacements between the first cyclic number series belonging to the code window.

2. A method according to claim 1, in which such rotations of the cyclic number series are used that at least some of these displacements are greater than one.

3. A method according to claim 1, further comprising the step of using such rotations of the first cyclic number series that the displacements of each code window define a position number in mixed base which gives the position of the first code window in the first direction and indicating the least significant displacement in the position number.

4. A method according to claim 3, in which the step of indicating the least significant displacement in the position number comprises using such rotations of the first cyclic number series that the least significant displacement is less than other displacements.

5. A method according to claim 3, in which the step of indicating the least significant displacement in the position number comprises using such rotations of the first cyclic number series that the least significant displacement lies in a first size range and other displacements lie in a second size range.

6. A method according to claim 1, comprising the step of creating different variants of the position code by letting the first cyclic number series in the first direction start in different positions for different variants.

7. A method according to claim 1, in which the position code also codes a plurality of positions in a second direction on the surface, comprising the steps of using a second cyclic number series, which has the characteristic that the position in the number series of each number sequence of a second predetermined length is determined unambiguously, printing out the second cyclic number series across the surface a plurality of times, different rotations of the second cyclic number series being used so that the second cyclic number series start at different start positions, the step of printing out comprising dividing the surface into a plurality of non-overlapping second code windows, each of which comprises a predetermined plurality of second cyclic number series, and using such rotations of the second cyclic number series that the position of each second code window in the second direction is coded by means of the start positions of the associated second cyclic number series.

12. A method according to claim 7, in which the second cyclic number series is identical to the first cyclic number series.

13. A method according to claim 7, in which the first cyclic number series is a binary number series.

14. A method according to claim 7, in which the first cyclic number series is printed out in columns across the surface and the second cyclic number series is printed out in rows across the surface.

15. A method according to claim 14, in which the printing out of the first and the second cyclic number series is carried out in such a way that each intersection of the raster lines in a raster which covers the surface is allocated a number from the first cyclic number sequence and a number from the second cyclic number sequence and the numbers belonging to each intersection are coded graphically by a mark on the surface in association with the intersection.

16. A method according to claim 15, in which the different possible combinations of numbers from the first and the second cyclic number series are coded by different locations of the mark relative to the intersection point.

17. A computer-readable computer program product which comprises a computer program with instructions to cause the computer to implement the method according to any one of claims 1, 7 or 8.

8. A method of providing a position code on a surface, which position code codes a plurality of positions in a second direction on the surface, comprising the steps of using a second cyclic number series, which has the characteristic that the position in the number series of each number sequence of a second predetermined length is determined unambiguously, printing out the second cyclic number series across the surface a plurality of times, different rotations of the second cyclic number series being used so that the second cyclic number series start in different start positions, wherein the step of printing out comprises dividing the surface into a second plurality of non-overlapping code windows, each of which comprises a predetermined plurality of second cyclic number series, and using such rotations of the second cyclic number series that the position of each second code window in the second direction is coded by means of the start positions of the associated second cyclic number series.

9. A method according to claim 8, further comprising the steps of using such rotations of the second cyclic number series that the start position of each second code window forms a position number in mixed base which gives the position of the second code window in the second direction, and indicating the least significant start position in the position number.

10. A method according to claim 9, in which the step of indicating the least significant start position in the position number comprises using such rotations of the second cyclic number sequence that the least significant start position is less than other start positions.

11. A method according to claim 9, in which the step of indicating the least significant start position in the position number comprises using such rotations of the second cyclic number series that the least significant start position lies in a first size range and other start positions lie in a second size range.

18. A method of determining a position, in a first direction, of an arbitrary partial surface of a predetermined size on a surface which is provided with a position code, which for the position coding in the first direction is based on a first cyclic number series, which has the characteristic that the position in the number series of each first number sequence of a first predetermined length is determined unambiguously and which is printed out a plurality of times on the surface with different rotations so that adjacent first cyclic number series are displaced relative to each other by predetermined displacements, comprising the steps of

identifying a plurality of first number sequences from the position code on the partial surface;

determining the position of each first number sequence in the first cyclic number series;

on the basis of these positions, determining the displacements between the adjacent cyclic number series containing the first number sequences from the partial surface,

wherein the steps of determining, based on the displacements, a position in the first direction of a first code window which said partial surface at least partly overlaps, which first code window is one of a plurality of code windows in a first direction, each of which comprises a predetermined plurality of first cyclic number series and has one number series overlapping one number series of adjacent first code windows.

19. A method according to claim 18, in which the step of determining said position of the first code window comprises determining which of the displacements corresponds to the least significant digit in a position number in mixed base, which gives the position of the first code window in the first direction.

20. A method according to claim 19, in which the displacement which corresponds to the least significant digit in the position number is determined to be the least of the displacements.

21. A method according to claim 19, in which the displacement which corresponds to the least significant digit in the position number is determined to be the displacement that lies in a first size range.

22. A method according to claim 19, further comprising the step of determining a first coordinate which gives the position of the partial surface in the first direction on the basis of said position number which gives the position of the first code window in the first direction and on the basis of which of the displacements corresponds to the least significant digit in the position number.

23. A method according to claim 18, further comprising the step of determining a position of said partial surface in a second direction on the surface, the position-coding pattern for the coding in the second direction being further based on a second cyclic number series, which has the characteristic that the position in the number series of each second number sequence of a second predetermined length is determined unambiguously and which is printed out a plurality of times of the surface with different rotations so that the second cyclic number series start in different start positions, comprising the steps of identifying a plurality of second number sequences from the position code on the partial surface, determining the position of each second number sequence in the second cyclic number series;

calculating the start positions of each of the second cyclic number series containing the second number sequences on the partial surface, based on the position of the partial surface in the first direction, and determining from the start positions a position in the second direction of a second code window which the partial surface at least partly overlaps, which second code window is one of a plurality of non-overlapping code windows in the second direction, each of which comprises a predetermined plurality of second cyclic number series.

24. A method according to claim 23, in which the step of determining the position of the second code window in the second direction comprises determining which of the start positions corresponds to the least significant digit in a position number in mixed base, which gives the position of the second code window in the second direction.

25. A method according to claim 24, in which the start position which corresponds to the least significant digit in the position number for the second code window is determined to be the least significant start position.

26. A method according to claim 24, in which the start position which corresponds to the least significant digit in the position number is determined to be the start position which lies within a first size range.

27. A method according to claim 23, further comprising the step of determining a second coordinate which gives the position of the partial surface in the second direction on the basis of said position number which gives the position of the second code window in the second direction and on the basis of which of the start positions corresponds to the least significant digit in the position number.

28. A method according to claim 27, further comprising the step of determining a third coordinate for the position of the partial surface on the surface by calculating, using the second coordinate, in which position the first cyclic number series in the first direction starts.

29. A method according to claim 23, in which the position code comprises a raster which extends over the surface, in which each intersection between the raster lines in said raster is allocated a number from the first cyclic number series and a number from the second cyclic number series, which numbers are coded by a graphic mark, in which the steps of identifying a plurality of first number sequences and identifying a plurality of second number sequences comprise decoding the marks which are found within said partial surface and separating the thus-obtained numbers in said plurality of first number sequences and said second number sequences.

30. A computer-readable computer program product which comprises a computer program with instructions to cause the computer to implement the method according to any one of claim 18 or 23.

31. A device for position determination, comprising a sensor for producing an image of a partial surface of a surface which is provided with a position code, and image processing means which are arranged to calculate based on the subset of the position code which is to be found in the image of the partial surface a position of the partial surface in accordance with the method according to any one of claim 18 or 23.

32. A device according to claim 31, which device is handheld.

33. A device according claim 32, in which the device has means for wireless transmission of position information.

34. A product which makes possible determination of a position, in a first direction, of an arbitrary partial surface of a predetermined size on a surface of the product which is provided with a position code, which for position-coding in the first direction is based on a first cyclic number series, which has the characteristic that the position in the number series of each first number sequence of a first predetermined length is determined unambiguously and which is printed out a plurality of times on the surface with different rotations so that adjacent first cyclic number series are displaced relative to each other by predetermined displacements, a plurality of first number sequences from the position code being identifiable on the partial surface, in order to determine the position of each first number sequence in the first cyclic number series, and the displacements between the adjacent first cyclic number series containing the first number sequences from the partial surface being determinable on the basis of these positions,

wherein, based on the displacements, a position in the first direction of a first code window, which said partial surface at least partly overlaps, is determinable, which first code window is one of a plurality of code windows in the first direction, each of which comprises a predetermined plurality of first cyclic number series and has one number series overlapping one number series of adjacent first code windows.

35. A product according to claim 34, in which for determining said position of the first code window, it is determined which of the displacements corresponds to the least significant digit in a position number in mixed base, which gives the position of the first code window in the first direction.

36. A product according to claim 35, in which the displacement which corresponds to the least significant digit in the position number is the least of the displacements.

37. A product according to claim 35, in which the displacement which corresponds to the least significant digit in the position number is the displacement which lies within a first size range.

38. A product according to claim 35, in which a first coordinate is arranged to give the position of the partial surface in the first direction on the basis of said position number which gives the position of the first code window in the first direction and on the basis of which of the displacements corresponds to the least significant digit in the position number.

39. A product according to claim 37, further comprising a position of said partial surface in a second direction on the surface, the position-coding pattern for the coding in the second direction being further based on a second cyclic number series, which has the characteristic that the position in the number series of each second number sequence of a second predetermined length is determined unambiguously and which is printed out a plurality of times on the surface with different rotations so that the second cyclic number series start in different start positions, a plurality of second number sequences from the position code on the partial surface being identifiable, by determining the position of each second number sequence in the second cyclic number series;

calculating, based on the position of the partial surface in the first direction, the start positions of each of the second cyclic number series containing the second number sequences on the partial surface, and determining from the start positions a position in the second direction of a second code window which the partial surface at least partly overlaps, which second code window is one of a plurality of non-overlapping code windows in the second direction, each of which comprises a predetermined plurality of second cyclic number series.

40. A product according to claim 39, in which the position of the second code window in the second direction is determined by which of the start positions corresponds to the least significant digit in a position number in mixed base, which gives the position of the second code window in the second direction.

41. A product according to claim 40, in which the start position which corresponds to the least significant digit in the position number of the second code window is determined to be the least significant start position.

42. A product according to claim 40, in which the start position which corresponds to the least significant digit in the position number is determined to be the start position which lies within a first size range.

43. A product according to claim 39, in which a second coordinate is determined which gives the position of the partial surface in the second direction on the basis of said position number which gives the position of the second code window in the second direction and on the basis of which of the start positions corresponds to the least significant digit in the position number.

44. A product according to claim 43, further comprising a third coordinate being determined for the position of the partial surface on the surface by calculating, using the second coordinate, in what position the first cyclic number series in the first direction starts.

45. A product according to claim 39 in which the position code comprises a raster which extends across the surface, each intersection between the raster lines in said raster being allocated a number from the first cyclic number series and a number from the second cyclic number series, which numbers are coded by a graphic mark, said plurality of first number sequences and said plurality of second number sequences being arranged to be identified by decoding the marks which are to be found within said partial surface and to separate the thus-obtained numbers in said plurality of first number sequences and said second number sequences.