METHOD OF INTERACTING WITH SUBSTRATE COMPRISING IR-ABSORBING CODING PATTERN

1 . A method of interacting with a printed substrate, said substrate comprising a coding pattern printed with an IR-absorbing ink, said method comprising the steps of:

operatively positioning an optically-imaging sensing device relative to the substrate and sensing at least part of the coding pattern; and

generating interaction data using the sensed coding pattern, wherein said IR-absorbing ink comprises a dye of formula (I):

wherein

M is Ga(A 1 );

A 1 is an axial ligand selected from the group consisting of: OH and halogen;

R 1 and R 2 may be the same or different and are selected from the group consisting of: hydrogen and C 1-12 alkoxy; and

W is a sulfonic acid group or salts thereof.

2 . The method of claim 1 , wherein each W is a cationic nitrogen salt of a sulfonic acid group.

3 . The method of claim 2 , wherein:

each W is SO 3 Z;

Z is N + (R m )(R n )(R s )(R t ); and

R m , R n , R s , R t may be the same or different and are independently selected from the group consisting of: H, C 1-8 alkyl, C 6-12 arylalkyl and C 6-12 aryl.

4 . The method of claim 1 , wherein R 1 and R 2 are both H.

5 . The method of claim 1 , wherein M is Ga(OH).

6 . The method of claim 1 , wherein the coding pattern identifies a substrate identity and said interaction data identifies said substrate identity.

7 . The method of claim 1 , wherein the coding pattern identifies a plurality of locations, and said interaction data identifies a position of the sensing device relative to the said substrate.

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

communicating the interaction data to a computer system for interpretation.

9 . The method of claim 8 , further comprising the step of:

causing the computer system to perform a predetermined action upon receipt of said interaction data.

10 . A system for interacting with a printed substrate, said system comprising:

a substrate comprising a coding pattern printed with an IR-absorbing ink; and

a sensing device for interacting with the substrate, said sensing device comprising an image sensor and a processor for generating interaction data using images captured by the image sensor,

wherein said IR-absorbing ink comprises a dye of formula (I):

wherein

M is Ga(A 1 );

A 1 is an axial ligand selected from the group consisting of: OH and halogen;

R 1 and R 2 may be the same or different and are selected from the group consisting of: hydrogen and C 1-12 alkoxy; and

W is a sulfonic acid group or salts thereof.

11 . The system of claim 10 , wherein each W is a cationic nitrogen salt of a sulfonic acid group.

12 . The system of claim 11 , wherein:

each W is SO 3 Z;

Z is N + (R m )(R n )(R s )(R t ); and

R m , R n , R s , R t may be the same or different and are independently selected from the group consisting of: H, C 1-8 alkyl, C 6-12 arylalkyl and C 6-12 aryl.

13 . The system of claim 10 , wherein R 1 and R 2 are both H.

14 . The system of claim 10 , wherein M is Ga(OH).

15 . The system of claim 10 , wherein the coding pattern identifies a substrate identity and said interaction data identifies said substrate identity.

16 . The system of claim 10 , wherein the coding pattern identifies a plurality of locations, and said interaction data identifies a position of the sensing device relative to the said substrate.

17 . The system of claim 10 , further comprising a computer system for interpreting the interaction data.