Identification card with concealed coding and a simple reader module to decode it
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United States of America Patent
Stats
-
Aug 27, 1985
Grant Date -
N/A
app pub date -
Sep 13, 1982
filing date -
Sep 16, 1981
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An instruction or identification card or badge for use in a time recording system, to authorize admission to restricted locations or for use in credit transactions comprises layers of material that is opaque to visible light but transparent to infra-red radiation. A code that is readable by an optoelectronic reader but is invisible in ordinary light is provided by transparent windows alternating with infra-red opaque regions arranged along a line parallel to one edge of the card, one binary digit being represented by wide rectangular windows and the other binary digit being represented by narrower windows that when read in a badge reader give different peak heights. The code is self-clocking and need occupy only a small portion of the card area.
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Cited Art Landscape
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