| 摘要 |
This invention relates to a method and apparatus for contactless identification of a label which incorporates passive resonators, with the aid of high-frequency magnetic fields. One significant feature of the inventive method is that large quantities of information of practical interest can be accommodated, despite the fact that the resonators can be given a Q-value which is so low as to enable the resonators to be given the form, e.g., of printed circuits mounted on plastic foil. The frequency stability requirement of the resonators is also low, which enables the labels to be produced very cheaply with the aid of suitable manufacturing techniques herefor, and also enables labels to be produced for one-time use only. The method is based on a high-frequency signal which is scanned over a broad frequency band and modulated at the same time, with appropriate detection, the modulation results in a response of narrower bandwidths than that obtained with earlier known methods, therewith enabling more resonators to be accommodated and to be separated within a given frequency range. The inventive apparatus with which the method is put into effect includes, inter alia, means for controlling the scan, modulation and amplification over the frequency band. One significant feature of the inventive apparatus resides in the provision of a coil arrangement which affords a comparatively large range while, at the same time, satisfying government regulations concerning maximum radiation powers. |
