Message alert system
US4506115A · kind A · utility
10Cited by
2References
1Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 12, 1983 |
| Grant date | Mar 19, 1985 |
| Priority date | — |
| Expiry date | Sep 12, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/537
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A lamp is provided on a telephone handset to notify the user that a message is waiting. The lamp is energized by a 1 hertz square wave obtained by demodulating a high frequency carrier sent from a transmitter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.