Telephone line sourced power supply
US5553138A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1994 |
| Grant date | Sep 3, 1996 |
| Priority date | — |
| Expiry date | May 13, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a telecommunication unit attached to a telephone line, power is provided by taking power from the telephone line when the unit is off-hook. When the unit remains on-hook, power is maintained to circuitry in the unit by a charge stored in a capacitor. When the capacitor's charge is reduced to a level no longer able to sustain operation of the unit, the unit is briefly taken off-hook, allowing the capacitor to recharge. Charge control of the capacitor is performed either by discrete circuitry or by a microcontroller, and further includes logic provisions preventing the unit from remaining off-hook for an unduly long period of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.