Radio IC card system
US6018641A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 10, 1997 |
| Grant date | Jan 25, 2000 |
| Priority date | — |
| Expiry date | Apr 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08G1/017
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A radio IC card system includes an IC card and a toll collector. When an automobile with the IC card passes by a tollgate, the toll collector installed in the tollgate transmits a first radio signal which is spread modulated using a pseudorandom noise (PN) code from an antenna. The first radio signal is received by the antenna of the IC card and is transmitted to a surface acoustic wave (SAW) correlator. The SAW correlator extracts a PN code included in the received signal, and outputs a peak signal. An accumulation circuit accumulates the peak signal. A threshold discharger is activated to switch on a relay switch when the output voltage of the accumulation circuit exceeds a constant value. Thereby, the voltage of a battery is supplied to a data communication unit. Then, the identification code of the IC card and a record of tollgates by which the automobile has passed are transmitted via radio signal to the toll collector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.