Circuits and methods for calibrating lens displacement
US8237851B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 2, 2009 |
| Grant date | Aug 7, 2012 |
| Priority date | — |
| Expiry date | May 25, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B13/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Embodiments of the present invention include circuits and methods for calibrating lens displacement in a voltage controlled actuator. In one embodiment, a calibration circuit comprises a programmable voltage source that provides a voltage to a control terminal of an actuator to set a lens displacement, a switch that selectively decouples said programmable voltage source from said control terminal, a current source that provides a reference current to said control terminal when the control terminal is decoupled from said programmable voltage source, a comparator that senses a voltage difference between said programmable voltage source and said control terminal, and a timer coupled to an output of the comparator. The timer measures a time period required to increase the control terminal voltage. The capacitance of the actuator may be determined and used to calibrate the position of a lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.