Identification system using regions of predetermined properties interspersed among regions of other properties

摘要

In an article identification system comprising a plurality of identification regions affixed on an article, a light emitting device for impinging an illuminating light beam onto at least some of the identification regions, a light receiving device for detecting light diffracted by the identification regions, and a determination unit for determining the authenticity of the article according to a pattern of diffracted light detected by the light receiving device, the identification regions consist of a combination of effective and ineffective identification regions which are hardly distinguishable by naked eyes. Thus, the potential forger is not able to know which regions are indeed effective without having any access to a genuine optical reader/writer, and has to duplicate all of the identification regions at a substantial cost and requiring a substantial amount of effort. On the other hand, the genuine optical reader/writer can simply disregard all of the ineffective identification regions, and the cost of the article identification system can be substantially reduced. Therefore, for given effort and cost, the effectiveness of the article identification system to discourage illicitly duplication can be increased.