US Patent 8186598 - Credit card with quantum dot indicia

http://www.freepatentsonline.com/8186598.html

There has been an interest in developing transparent credit and bank cards but there is difficulty for these cards to be read by ATM machines. This patent from American Express teaches using quantum dot ink for detection by ATM sensors. Claim 1 reads:

1. A card having a portion comprising:

a layer that is at least one of translucent and transparent; and

a first infrared blocking compound associated with said layer, wherein said first infrared blocking compound comprises a quantum dot compound.

US Patent 8066190 - Transparent credit card with nanostructured ink marking

http://www.freepatentsonline.com/8066190.html

Transparency is a desirable feature of credit and debit cards but can make the inclusion of encoding indicia difficult. This patent from American Express teaches using quantum dots and indium tin oxide nanoparticles in an ink for creating transparent security indicia on these cards readable by UV light. Claim 1 reads:

1. A transaction card having a portion comprising:

a layer that is at least one of translucent and transparent;

a first infrared blocking compound associated with said layer;

a second infrared blocking compound associated with said layer,

wherein said first infrared blocking compound further comprises nanocrystalline indium tin oxide particles,

wherein said second infrared blocking compound comprises a quantum dot compound.

US Patent 7837116 - Credit card with quantum dot IR blocking material

http://www.freepatentsonline.com/7837116.html

This patent from American Express is based on a series of continuations going back to 1999 and includes claims covering a transparent credit card having identification materials including quantum dots to provide proper sensing in an ATM as well as indicia for counting the cards on an assembly line during manufacture. Claim 1 reads:

1. A financial transaction card comprising:

a card body adapted to substantially transmit radiation in a visible light wavelength region;

said card body comprising a machine recognizable compound containing infrared blocking materials associated with said card body, said infrared blocking materials comprising a mixture of an IR-absorbing compound, a phosphor compound, and a quantum dot compound;

said machine recognizable compound blocks transmission of incident infrared radiation.