Driving circuit for double solenoid focus actuator
US5070489A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 1989 |
| Grant date | Dec 3, 1991 |
| Priority date | — |
| Expiry date | Aug 1, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0927
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A circuit for driving a focus actuator of the "double-solenoid" (i.e. twin-coil) variety comprises circuit means for selectively supplying current to one or the other of the actuator's coils in such a manner as to eliminate any dead-band discontinuity in the actuator response while current-switching between the coils. Such circuitry comprises a current source and/or amplifier for selectively providing current to the actuator coils, means for detecting the difference in current flowing in the coils, an a differential amplifier, connected in a feedback loop, for comparing the output of the detecting means with a signal indicating the focal position of a focusing lens. The output of the differential amplifier is used to control the output of the current source, controlling which of the two actuator coils receives current and how much.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.