Inductive load driver circuit effecting slow hold current delay and fast turn off current decay
US4234903A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1978 |
| Grant date | Nov 18, 1980 |
| Priority date | — |
| Expiry date | Feb 27, 1998 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02D2041/2058
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
An inductive load driver circuit comprising first and second switch means and high and low impedance load current decay means. For the duration of a load actuation signal the first switch means are responsive to the magnitude of the load current to complete and interrupt a first current path to the load to cycle the load current between first and second levels. The second switch means are enabled for the duration of the load actuation signal to complete a second current path to the load when the first switch means interrupts the first current path. When completed the second current path comprises the low impedance decay means allowing the load current to decay slowly from the first current level to the second level to provide during such slow decay a load current sufficient to maintain actuation of the inductive load. The end of the load actuation signal disables the second switch means to interrupt the second current path and thereby require the load current to decay rapidly through the high impedance decay means. In one embodiment, the second switch means comprise an SCR disabled by a final momentarily turn ON of the first switch means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.