Patterned platelets

Abstract

Patterned platelets are platelets made with specified shapes and sizes. The various sizes and shapes of the platelets are used to code articles and substances to which they are applied. The patterned platelets can be in inks or paints applied to articles. The platelets can be further coded by markings thereon or by spectral or polarization codes rather than just the distribution of sizes and shapes. The patterned platelets can be made from any materials buy subtractive or additive processes. A patterned platelet can also be made by an actinic polymer being applied to a substrate and a mask applied to allow only the desired size and shape to be exposed to radiation curing the unmasked portion of the polymer on the substrate. The polymer can be cholesteric liquid crystals with the properties of reflecting polarized light of selected wavelengths to code the crystals in addition to the size and shape codes. The cholesteric liquid crystals may also be doped with materials which absorb a portion of the wavelengths which would otherwise be reflected further coding the patterned platelets. Codes of the patterned platelets can be composed of the distribution of the platelets alone or in combination with the position of the platelets on an object. A code with the presence or absence of a specified patterned platelet in a specified location could be a binary code. If n different patterned platelets are used in each of x positions a code with x to the nth power combinations is possible.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to patterned platelets. More particularly the invention relates to platelets having specified shapes, sizes and optical properties, optionally with markings thereon, such that the platelets can be applied to objects to tag and identify the objects with unique codes. The platelets can be pigments in inks or paints applied to an object. The platelets can also be mixed in with other materials to tag them such as in liquids or solids. 1. Description of the Related Art Counterfeiting of articles and documents has been a problem in the past. Further, it is also useful in many industries to be able to trace of the origin of goods and documents. In the past, many methods have been introduced to tag articles such that they can be easily and positively identified in the future and to prevent tampering or counterfeiting activities. Some of these methods including using flop colors and holograms on platelet pigment...

AI Technical Summary

Benefits of technology

The platelets can also be made to reflect distinctive portions of the spectrum of light to further identify the platelets for tagging purposes. Each platelet can have one or ore sections of its surface reflect different spectral codes. CLC platelets can be made to electively reflect wide or narrow bands of light. For example, platelets can be made to reflect red or green or blue or white light or even light not in the visible spectrum. A platelet can have one section reflect green right circularly polarized light and another section reflect blue left polarized light. The light reflected can be used to easily identify the platelets used. Patterns of colors of light reflecting pigments can be used to further code the platelets. By using dopant materials in the CLC platelets, spectral band absorbing identifiers can be placed in the platelets further coding the platelets to be used as tags.

Another object of this invention is to produce platelets having substantially identical lateral dimensions or areas, resulting in a very narrow platelet size distribution.

Another object of this invention is to reduce the cost of producing pigments by eliminating milling and sieving steps.

Another object of this invention is to eliminate production of platelets outside a desired range, thus reducing waste.

Another object of the invention is to produce patterned platelets without using expensive hard to use molds.

Problems solved by technology

Counterfeiting of articles and documents has been a problem in the past.

Further, the various sieving steps add to the cost of processing the platelets.

One recent development was to make controlled shape and size platelet pigments by molding polymers as shown in patent WO98 / 12265 however the molding process is difficult to use, wastes a lot of expensive material and is costly.

Another drawback is removing odd shaped, notched or angled pieces from the mold.

This process results in a lot of wasted materials which are costly to make.

It will be appreciated that prior art platelet pigments cannot cost effectively produce the ultra-narrow size distribution, have not taught low cost easy to make the production of platelets with regular shapes, and they have not taught how pigments can be endowed with markings or codes using spatial marks, polarization or spectral marks.

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