
US Patent No: 5,149,578
Number of patents in Portfolio can not be more than 2000
Multilayer film for tamper indication by use of optical interference reflection
Stats
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Sep 22, 1992
Issued date -
Dec 23, 1991
filing date -
07/814,237
serial no -
In Force
status
Importance
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Abstract
A multilayer film including contiguous layers of two or more diverse thermoplastic materials of differing refractive indices whereby the film retains a permanent color change as evidence of tampering or an attempt at tampering when the yield point of at least one of the diverse materials has been at least equalled by the strain associated with such tampering or with such an attempt at tampering, and where before such yield point is at least equalled the wavelength of an unsuppressed reflectance of normally incident light is not within the visible spectrum while after such yielded point is at least equalled the reflectance is retained in the visible spectrum.
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First Claim
Related Publications
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International Classification(s)
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Cited Art
| Patent Info | (Count) | # Cites | Year |
|---|---|---|---|
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| 4,937,134 Elastomeric optical interference films | 134 | 1989 | |
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| 4,837,061 Tamper-evident structures | 48 | 1987 | |
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| 2003/0137,680 IMAGE PROCESSING APPARATUS, METHOD OF CONTROLLING SAME, AND IMAGE PROCESSING SYSTEM | 1998 | ||
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| 4,469,725 Identification card | 20 | 1982 | |
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| 4,721,217 Tamper evident optically variable device and article utilizing the same | 75 | 1986 | |
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| 4,717,615 Multi-layer foil and process for the production thereof | 25 | 1986 | |
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| 4,310,584 Multilayer light-reflecting film | 147 | 1979 | |
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| 4,890,763 Tamper resistant package and method of making same | 22 | 1988 | |
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| 4,417,784 Multiple image encoding using surface relief structures as authenticating device for sheet-material authenticated item | 59 | 1981 | |
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| 4,876,311 Opaque synthetic resins | 15 | 1988 | |
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| 4,516,679 Tamper-proof wrap | 38 | 1982 | |
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| 4,733,786 Container and innerseal capable of indicating heat tampering | 19 | 1986 | |
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| 4,986,063 Method and apparatus for compacting grass, leafage or similar material | 6 | 1989 | |