The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 01, 1994
Filed:
Apr. 30, 1992
Gary J Smith, Glenburnie, CA;
Robert A Innes, Kingston, CA;
Alcan International Limited, Montreal, CA;
Abstract
Color change devices which are capable of undergoing a color change on bending. The devices comprise a flexible substrate having a color generating metal (e.g. a valve metal such as Ta or Nb) at at least one surface and an intimately contacting optically thin anodic film covering the color generating metal and generating a visible color by light interference and absorption effects. The thin anodic film is produced by anodizing the color generating metal in the presence of an adhesion-reducing agent (e.g. a fluoride) for weakening the normally tenacious bond between the anodic film and the metal. Devices of this kind capable of being activated by bending, as well as by separation of the constituent layers, are produced by carrying out the anodization step in the presence of a particular concentration of the adhesion reducing agent from a narrow range (e.g. 40-350 ppm of fluoride). The devices can be used as tamper evident labels and the like which show evidence of removal of the labels from articles to which they were originally attached as an indication of tampering.