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High chroma multilayer interference platelets

  • US 5,569,535 A
  • Filed: 04/22/1994
  • Issued: 10/29/1996
  • Est. Priority Date: 12/28/1979
  • Status: Expired due to Term
First Claim
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1. A collection of color shifting interference thin film platelets which change color as the angle of incident light or viewing changes for use in a medium for producing a color shifting coating, said collection of color shifting interference thin film platelets being characterized in that each platelet has first and second parallel planar outer surfaces and an edge thickness perpendicular to the first and second parallel planar outer surfaces, each of said platelets comprising a metal reflecting layer having first and second reflective surfaces and a multilayer interference thin film structure disposed on each of the first and second reflective surfaces, the multilayer interference thin film structure comprising a pair of layers consisting of a dielectric layer formed of a dielectric material and a semi-opaque metal layer, said pair being disposed so that the dielectric layer is directly adjacent to the metal reflecting layer and the semi-opaque metal layer faces away from the metal reflecting layer, each platelet having an aspect ratio of at least 2:

  • 1 for the longest dimension of the first and second outer surfaces in comparision to the edge thickness of the platelet, each platelet having a maximum dimension on any surface of about 2-200 microns.

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