Article identification apparatus and method using a ferromagnetic tag

摘要

Information is encoded on tags preferably in a form emulating conventional bar coding, in which ferromagnetic strips correspond to bars and nonferromagnetic spaces correspond to the absence of bars. The tags thus can be embedded within an article or otherwise concealed from visual scanning or inspection. The tags are read by scanning with a magnetic reader including an excitation coil and a pickup coil. Relative movement between the tags and the scanner induces a signal in the pickup coil only when a bar is scanned, so that the phase and timing of the induced signals contain information corresponding to the relative placement and width of the ferromagnetic bars and strips. Those signals are processed to provide an output signal emulating the output from a conventional optical bar code scanner.