Button illumination for repertory dialer with low battery voltage indication
US4339632A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1980 |
| Grant date | Jul 13, 1982 |
| Priority date | — |
| Expiry date | Nov 26, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/22
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A display illuminating circuit for a repertory dialer telephone set allows for a subscriber to operate a desired repertory button in low ambient light emergency situations. The circuit illuminates the desired buttons by distinguishable colors of light-emitting elements. Activation of the illumination circuit occurs in response to the telephone set going off-hook and then only for a limited period to conserve battery life. A battery voltage monitoring arrangement provides an indication when a local battery needs to be replaced. In response to an activation signal provided by the voltage monitoring arrangement, the light-emitting elements flash at a level that is detectable by the subscriber going off-hook even in normal ambient light conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.