System for identifying particular objects
US4739328A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1986 |
| Grant date | Apr 19, 1988 |
| Priority date | — |
| Expiry date | Jul 14, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2009/0092
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A reader interrogates an object. The object has a tag with a data source such as a read-only memory (ROM) which produces an identifying sequence of binary 1's and 0's in an individual pattern and transmits these signals to the reader. Each "1" or "0" is converted to a plurality of signal cycles at first and second harmonic frequencies. For example, a "1" may be identified by two signal cycles at the second frequency (e.g. 40 kHz) and then one signal cycle at the first frequency (e.g. 20 kHz) and a "0" may be identified by a signal cycle at the first frequency and then two signal cycles at the second frequency. The transponder also produces a plurality of signal cycles in an individual code (different from any combination of "1's" and "0's") to indicate the end of the transmission of the signal cycles identifying the object and the start of another transmission. The reader receives the signal cycles identifying the object and delays these signal cycles by (a) a first time such as 1/4 period of a cycle at the second frequency, (b) a second time such as 1/2 of such period and (c) a third time corresponding to such period. The reader compares the received signals and the first delayed …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.