Symmetric tags

• US 7,111,791 B2
• Filed: 04/09/2003
• Issued: 09/26/2006
• Est. Priority Date: 03/04/2003
• Status: Expired due to Fees

• Current Assignee: Silverbrook Research Pty Limited
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Lapstun, Paul
• Primary Examiner(s): Kim, Ahshik
• Application Number:
  US10/410,484
• Publication Number:
  US 20040173687A1
• Time in Patent Office: 1,266 Days
• Field of Search: 235/494, 235/462.09, 235/462.1, 235/462.07, 235/375, 235/289, 382/287, 382/289
• US Class Current: 235/494
• CPC Class Codes: G06K 19/06037 multi-dimensional coding

Abstract

Machine-readable coded data for use in the identity-coding and position-coding of surfaces. The machine-readable coded data being disposed on or in a substrate in accordance with a layout having mirror symmetry and n-fold rotational symmetry, where n is at least two, the layout including n identical first sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, the layout further including n identical second sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, the coded data disposed in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout, the coded data disposed in accordance with each sub-layout further including reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of its corresponding reflected sub-layout.

Claims

1. Machine-readable coded data disposed on or in a substrate in accordance with a layout having mirror symmetry and n-fold rotational symmetry, where n is at least two, the layout including n identical first sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, the layout further including n identical second sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, the coded data disposed in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout, the coded data disposed in accordance with each sub-layout further including reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of its corresponding reflected sub-layout.

2. Machine-readable coded data according to claim 1 wherein the rotation-indicating data and the reflection-indicating data together distinguish the rotation and reflection of the sub-layout from the rotation and reflection of each of the other sub-layouts within the layout.

3. Machine-readable coded data according to claim 1 wherein the coded data is redundantly encoded and the coded data of each sub-layout includes at least one coded data codeword.

4. Machine-readable coded data according to claim 3 wherein the coded data is redundantly encoded using a Reed-Solomon encoding.

5. Machine-readable coded data according to claim 1 wherein each sub-layout defines a plurality of positions of data elements, the sub-layouts being interleaved with each other without any two data elements overlapping each other.

6. Machine-readable coded data according to claim 1 wherein the layout is repeated on the substrate to form a super-layout.

7. Machine-readable coded data according to claim 6 wherein the layouts are packed together on the substrate to form the super-layout.

8. Machine-readable coded data according to claim 1 wherein the layout takes the form of any of the following shapes:

linear;

square;

rectangular;

triangular;

or

hexagonal.

9. Machine-readable coded data according to claim 1 wherein the coded data includes one or more target features for enabling preliminary location and rotation of the layout to be determined by a machine used to read the coded data.

10. Machine-readable coded data according to claim 9 wherein the target features are configured to enable perspective correction of the coded data of the, or each, layout upon reading by the machine.

11. Machine-readable coded data according to claim 10 wherein the coded data include at least four of the target features, and that a plurality of the layouts share some of the same target features.

12. A surface bearing machine-readable coded data, the machine-readable coded data being arranged in accordance with a layout having mirror symmetry and n-fold rotational symmetry, where n is at least two, the layout including n identical first sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, the layout further including n identical second sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, the coded data disposed in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout, the coded data disposed in accordance with each sub-layout further including reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of its corresponding reflected sub-layout.

13. A surface according to claim 12 further including visible markings.

14. A surface according to claim 12 configured for use as an interface surface for enabling user interaction with a computer.

15. A method of generating an interface surface, including the steps of:

receiving, in a printer, user data;

generating machine-readable coded data incorporating the user data, the machine-readable coded data being arranged in accordance with a layout having mirror symmetry and n-fold rotational symmetry, where n is at least two, the layout including n identical first sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, the layout further including n identical second sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, the coded data being arranged in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout, the coded data being arranged in accordance with each sub-layout further including reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of its corresponding reflected sub-layout; and

printing the coded data onto a substrate.

16. A method according to claim 15 wherein the method further includes the step of printing visible markings on the substrate, preferably simultaneously with the coded data.

17. A method of using a sensing device to read machine-readable coded data, the machine-readable coded data being disposed on or in a substrate in accordance with a layout having mirror symmetry and n-fold rotational symmetry, where n is at least two, the layout including n identical first sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, the layout further including n identical second sub-layouts rotated 1/n revolutions apart about a center of rotational symmetry of the layout, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, the coded data disposed in accordance with each sub-layout including rotation-indicating data that distinguishes the rotation of that sub-layout from the rotation of at least one other sub-layout within the layout, the coded data disposed in accordance with each sub-layout further including reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of its corresponding reflected sub-layout,

the method including the steps of:

(a) reading, using the sensing device, the coded data of the layout;

(b) decoding the coded data of at least one of the sub-layouts of the layout, thereby determining at least the rotation-indicating data and reflection-indicating data of that sub-layout; and

(c) using the rotation-indicating data and reflection-indicating data to interpret the meaning of at least some of the coded data.

18. A method according to claim 17 wherein step (a) includes the substeps of:

imaging the substrate to generate an image thereof;

processing the image to locate one or more target features of the coded data; and

on the basis of the located target features, determining a position of at least one of the sub-layouts.