Microparticles with visual identifying means
AssigneeMinnesota Mining and Manufacturing Company
InventorEdward J. Stevens
Life of this patent
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Abstract
Microparticles encoded for retrospective identification of substances into which they are incorporated. The novel microparticles have flat surfaces bearing repetitive identifying indicia such as alphanumerics which can be visually interpreted under magnification. The indicia may provide only part or all of the code.
Claims20
In a batch of organic microparticles which are uniformly encoded for retrospective identification, each of the same thickness not significantly exceeding 500 micrometers and having two surfaces which are generally flat and parallel to each other across its broadest dimension, the broadest dimension of most of the microparticles being no greater than 1000 micrometers but greater than said thickness, the improvement comprising:
- at least one of the flat surfaces of each microparticle bears identifying indicia selected from alphanumerics and symbols which provide a repetitive code that (a) is randomly located with respect to the edges of the microparticle, (b) can be visually interpreted under magnification, and (c) repeats in any direction within a distance less than said broadest dimension so that examination of a typical microparticle of average size should reveal said code.
Method of making a batch of microparticles useful for retrospective identification comprising the steps of:
- (1) making an organic sheet of substantially uniform thickness not significantly exceeding 500 micrometers,
- (2) forming on at least one face of the sheet identifying indicia selected from alphanumerics and symbols which provide a repetitive code that can be visually interpreted under magnification and repeats in any direction within a distance not significantly exceeding 500 micrometers, and
- (3) comminuting the sheet at random into a batch of microparticles, each having two surfaces which are generally flat and parallel to each other and contain portions of said indicia, the broadest dimension of most of the microparticles being no greater than 1000 micrometers, but greater than said distance so that examination of a typical microparticle of average size should reveal said code.
Dependencies are inferred from the claim text.