Electronic telephone device
US5182767A · kind A · utility
26Cited by
7References
8Claims
0Family size
Inventor
Key dates
| Filing date | Apr 4, 1991 |
| Grant date | Jan 26, 1993 |
| Priority date | — |
| Expiry date | Apr 4, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07F7/0866
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The device includes an acoustic transmitter (10), a tone generator (12), a memory (14) containing an identification code (N) and a service key (C), and an electronic circuit (16). A digital message transmitted depends on N and C and changes with each use. The time limitation moment of the device is determined. The device appears in the form of a token.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.