Method and apparatus to drive a linear resonant actuator at its resonant frequency
US9054627B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 10, 2012 |
| Grant date | Jun 9, 2015 |
| Priority date | — |
| Expiry date | Oct 1, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P25/02
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for driving a Linear Resonant Actuator (LRA) is provided. During a first off interval, the back-emf of the LRA is measured. During a first off interval, a timer is started when the back-emf reaches a predetermined threshold, and after a predetermined delay has lapsed following the back-emf reaching the predetermined threshold during the first off interval, the LRA is driven over a drive interval having a length and drive strength. A second off interval is entered following the drive interval, and during the second off interval, the back-emf of the LRA is measured. During the second off interval, the timer is stopped when the back-emf reaches the predetermined threshold. The value from the timer that corresponds to the duration between the back-emf reaching the predetermined threshold during the first off interval and the back-emf reaching the predetermined threshold during the second off interval determines the length.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.