Driving mechanism for keeping feedback cycle constant, apparatus with the mechanism, and its control method
US6047135A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 20, 1998 |
| Grant date | Apr 4, 2000 |
| Priority date | — |
| Expiry date | Nov 20, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02N2/025
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A driving device, for driving a compensation lens of a camera, with a feedback control for an actuator therefor in which it is easy to keep a feedback cycle constant. In the feedback control, the feedback cycle is kept constant by counting the number of PWM pulses for driving the actuator. In case that the actuator is of a type in which it is controlled by more than one PWM pulse trains with different phases, one pulse train with predetermined phase is continuously supplied to the actuator even when the actuator is not driven, where the number of pulses in the one pulse train is counted so as to keep the feedback cycle constant. The actuator preferably employs a piezoelectric element which expands and contracts in response to a wave-form pulse included in the PWM pulse train.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.