Optically-readable cards
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United States of America Patent
Stats
-
Mar 19, 1985
Grant Date -
N/A
app pub date -
Sep 15, 1982
filing date -
Aug 2, 1982
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An optically-readable value card for use in a vending system for vending goods or services includes a plurality of heat-sensitive optically-readable value elements each of which, upon heating to a first temperature above ambient, changes its color in a reversible manner, but upon heating to a second temperature above ambient and higher than the first temperature, changes to a second color in an irreversible manner. Each of the value elements is in the form of a light window having a layer of a thermochromic material which changes its color in a reversible manner when heated to the first temperature, and a layer of a thermographic material which changes its color in an irreversible manner when heated to the second temperature.
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