Coding pattern with optimal number of target elements in each tag

• US 8,028,925 B2
• Filed: 02/05/2008
• Issued: 10/04/2011
• Est. Priority Date: 02/08/2007
• Status: Expired due to Fees

• Current Assignee: Silverbrook Research Pty Limited
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Lapstun, Paul
• Primary Examiner(s): Lee; Michael G
• Assistant Examiner(s): GUDORF, LAURA A
• Application Number:
  US12/025,746
• Publication Number:
  US 20080193007A1
• Time in Patent Office: 1,337 Days
• Field of Search: 235/375, 235/487, 235/494
• US Class Current: 235/494
• CPC Class Codes: G06F 2203/0337 Status LEDs integrated in the mouse to provide visual feedback to the user about the status of the input device, the PC, or the user
• CPC Class Codes: G06F 2203/0384 Wireless input, i.e. hardware and software details of wireless interface arrangements for pointing devices
• 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 19/06 characterised by the kind of the digital marking, e.g. shape, nature, code
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06T 7/32 using correlation-based methods

Abstract

A substrate having a coding pattern disposed on a surface thereof is disclosed. The coding pattern has target elements defining a target grid. The target grid has cells, wherein neighboring cells share target elements. A plurality of data elements are contained in each cell. Tags are defined by a plurality of contiguous cells and each tag has respective local tag data encoded by a respective set of the data elements. Each tag has at least nine target elements, which facilitates accurate observation of a perspective distortion of the target elements.

Claims

1. A substrate having a coding pattern disposed on a surface thereof, said coding pattern comprising:

a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements;

a plurality of data elements contained in each cell; and

a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements,

wherein each tag comprises at least 9 target elements and each cell comprises translation data encoded by a respective set of said data elements, said translation data identifying a translation of said cell relative to a tag containing said cell.

2. The substrate of claim 1, wherein each tag comprises at least 16 target elements.

3. The substrate of claim 1, wherein each tag comprises at least 25 target elements.

4. The substrate of claim 1, wherein each tag is square and comprises M² contiguous square cells, wherein M is an integer having a value of at least 2.

5. The substrate of claim 1, wherein said target elements are configured to facilitate computation of a perspective distortion of said target grid when a portion of said coding pattern is acquired by an optical sensing device.

6. The substrate of claim 1, wherein said target elements are sufficiently large to be distinguishable from said data elements by a low-pass filter.

7. The substrate of claim 1, wherein said target elements are target dots and said data elements are macrodots.

8. The substrate of claim 7, wherein each target dot has a diameter of at least twice that of each macrodot.

9. The substrate of claim 7, wherein said macrodots encode data values by pulse position modulation.

10. The substrate of claim 9, wherein a n-bit portion of data is represented by a macrodot occupying one of 2ⁿ possible positions within a cell, each position representing one of 2ⁿ possible data values, wherein n is an integer.

11. The substrate of claim 1, wherein each tag comprises a plurality of replications of said local tag data, such that any tag-sized portion of said coding pattern is guaranteed to contain said local tag data irrespective of whether a whole tag is contained in said portion.

12. The substrate of claim 11, wherein each tag is square and comprises four replications of said local tag data, each replication being positioned within a respective quarter of said tag.

13. The substrate of claim 1, wherein said local tag data identifies a location of a respective tag.

14. The substrate of claim 1, wherein each tag comprises common data encoded by a respective set of said data elements, wherein said common data is defined as data common to a plurality of contiguous tags.

15. The substrate of claim 14, wherein each cell comprises a fragment of said common data, and contiguous cells are arranged such that any tag-sized portion of said coding pattern is guaranteed to contain said common data irrespective of whether a whole tag is contained in said portion.

16. The substrate of claim 14, wherein said common data is region identity data uniquely identifying a region of said surface.

17. The substrate of claim 16, wherein said common data uniquely identifies said substrate.

18. The substrate of claim 1, wherein each cell comprises orientation data encoded by a respective set of said data elements, said orientation data identifying an orientation of said coding pattern with respect to said surface.

19. The substrate of claim 1, wherein each cell defines a symbol group, each symbol group comprising a plurality of Reed-Solomon symbols encoded by a plurality of said data elements.