Optically variable and machine-readable device for use on security documents
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United States of America Patent
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Apr 4, 1995
Grant Date -
N/A
app pub date -
Mar 30, 1992
filing date -
Mar 30, 1992
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An optically variable device for use on security documents to deter unauthorized reproduction is provided which contains a warning message that is not readily apparent to an observer but that reproduces as a visible warning message when copied. The device comprises a pattern of light reflecting surfaces which comprise a reflection diffraction grating having a plurality of grooves that vary in orientation and blaze angle. In an alternative embodiment, a machine-readable optically variable device is provided in which the pattern of specularly light-reflecting surfaces produces a machine-readable message in response to light impinging on the device.
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