Information encoding on surfaces by varying spectral emissivity

• US 20030146288A1
• Filed: 02/01/2003
• Published: 08/07/2003
• Est. Priority Date: 02/05/2002
• Status: Active Grant

• Current Assignee: William Berson
• Original Assignee: William Berson
• Inventors: Berson, William
• Granted Patent: US 7,044,386 B2
• Time in Patent Office: Days
• US Class Current: 235/494
• CPC Class Codes: G06K 1/123 for colour code marks
• CPC Class Codes: G06K 19/06028 using bar codes
• CPC Class Codes: G06K 2019/06225 using wavelength selection, e.g. colour code
• CPC Class Codes: G06K 2019/06271 Relief-type marking
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks

Abstract

A method for applying surface modifications in at least two patterns that differ in spectral emissivity by known amounts. The patterns form an information-encoding sequence of transitions of differential emissivity along a scan path over the patterns, that encodes a set of information. This information is decoded by a scanner sensitive to emissivity in the given portion of the electromagnetic spectrum, and sensitive to transitions in emissivity of the known amounts, when scanned along the scan path, combined with knowledge of the expected emissivity values of the patterns. This provides secure informational marking of articles and documents, including mail. The patterns may be visible, or hidden, but the emissivity values are not duplicated by standard office equipment, so authenticity of the patterns can be determined using the special emissivity scanner.

Claims

1. A method for encoding information on surfaces, comprising the steps of:

providing a surface;

applying to the surface a first pattern using a first type of surface-modification having a known first emissivity value;

applying to the surface a second pattern using a second type of surface-modification having a known second emissivity value, the first and second emissivity values differing from each other by a known amount;

the first and second patterns forming an information-encoding sequence of transitions of differential emissivity along a scan path over the patterns, that encodes a given set of information;

whereby an emissivity sensor that is sensitive to transitions in emissivity of the known amount, when scanned along a scan path over the patterns, will detect emissivity transitions that encode the given set of information.

2. The method of claim 1, wherein:

the first type of surface modification has a given appearance based on light reflection and absorption in the visible spectrum;

the second type of surface modification has substantially the same given appearance based on light reflection and absorption in the visible spectrum; and

the first and second inks are applied in a combined pattern that does not reveal the given set of information in the visible spectrum.

3. The method of claim 1, wherein the known amount of emissivity differential is at least 0.05.

4. The method of claim 1, wherein:

the first type of surface modification is a first ink; and

the second type of surface modification is a second ink.

5. The method of claim 1, wherein:

the first type of surface modification is a first surface texture; and

the second type of surface modification is a second surface texture.

6. The method of claim 5, wherein the first and second surface modifications are created by embossing the surface with an electromechanical dot matrix printer.

7. The method of claim 5, wherein the first and second surface modifications are created by applying different dot density patterns on the surface by raised printing.

8. The method of claim 1, further comprising the steps of:

providing a scanner that sensitive to transitions in emissivity of the known amount;

scanning the patterns to detect emissivity transitions; and

decoding the given set of information.

9. A method for encoding information on surfaces, comprising the steps of:

providing a surface;

providing a first ink having a known first emissivity value when dry, as measured in a given portion of the electromagnetic spectrum;

providing a second ink having a known second emissivity value when dry, as measured in said given portion of the electromagnetic spectrum, the first and second emissivity values differing from each other by a known amount;

applying to the surface a first pattern using the first ink;

applying to the surface a second pattern using the second ink, the first and second patterns forming an information-encoding sequence of transitions of differential emissivity along a scan path over the patterns, that encodes a given set of information;

whereby an emissivity sensor that is sensitive to the given portion of the electromagnetic spectrum, and sensitive to transitions in emissivity of the known amount, when scanned along a scan path over the patterns, will detect emissivity transitions that encode the given set of information.

10. The method of claim 9, wherein:

the first and second inks have substantially the same appearance in the visible spectrum; and

the first and second inks are applied in a combined pattern that does not reveal the given set of information in the visible spectrum.

11. The method of claim 9, further comprising the steps of:

providing a scanner that is sensitive to the given portion of the electromagnetic spectrum, and is sensitive to transitions in emissivity of the known amount;

scanning the patterns to detect emissivity transitions; and

decoding the given set of information.

12. The method of claim 9, further comprising the steps of:

providing at least one additional ink, having a known emissivity value in said given portion of the electromagnetic spectrum, the first, second, and at least one additional inks having emissivity values in said given portion of the electromagnetic spectrum that differ from each other by known amounts;

applying to the surface at lease one additional pattern using the at least one additional ink, the patterns forming an information-encoding sequence of transitions of differential emissivity along a scan path over the patterns that encodes a given set of information.

13. A method for encoding information on surfaces, comprising the steps of:

providing a surface having a known first emissivity value, as measured in a given portion of the electromagnetic spectrum;

applying a first texture to the surface in a first pattern that produces a second known emissivity value as measured in said given portion of the electromagnetic spectrum;

applying a second texture to the surface in a second pattern that produces a third known emissivity value, as measured in said given portion of the electromagnetic spectrum, the first, second, and third emissivity values differing from each other by known amounts, the second and third patterns forming an information-encoding sequence of transitions of differential emissivity along a scan path over the patterns, that encodes a given set of information;

whereby an emissivity sensor that is sensitive to the given portion of the electromagnetic spectrum, and sensitive to transitions in emissivity of the known amount, when scanned along a scan path over the patterns, will detect emissivity transitions that encode the given set of information.

14. The method of claim 13, further comprising the steps of:

providing a scanner that is sensitive to the given portion of the electromagnetic spectrum, and is sensitive to transitions in emissivity of the known amount;

scanning the patterns to detect emissivity transitions; and

decoding the given set of information.