Ringing detector for use by the deaf
US4379210A · kind A · utility
16Cited by
3References
11Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 28, 1981 |
| Grant date | Apr 5, 1983 |
| Priority date | — |
| Expiry date | May 28, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A ringing detector circuit for use by the deaf which may be connected between the tip and ring conductors (11, 12) of a subscriber set to cause an incandescent lamp (40) to flash to half brightness when ringing voltage is applied to the line. Closing a manual switch (22) allows the lamp (40) to burn at half brightness when the phone is not ringing and to flash to full brightness when the phone is ringing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.