Method and apparatus for automatic deployment of camera lens
US5652928A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 1996 |
| Grant date | Jul 29, 1997 |
| Priority date | — |
| Expiry date | Mar 27, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B17/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Camera autofocus apparatus and method employing an autoranging device to determine a lens destination focus position in terms of a target number of signal pulses from a lens motion sensor photo-interrupter. A lens drive motor is initially driven at maximum speed by a 100% pulse width modulated drive signal. At a fixed number of signal pulses in advance of the target, the average motor speed is calculated and a reduced pulse with modulated drive signal, determined based on the calculated motor speed, is applied to the drive motor to cause the lens to arrive at a uniform speed at a near destination focus position that is suitable for application of a standard motor stopping routine. During the motor stopping routine, the motor is initially "plugged" (reverse polarity drive signal) and the signal pulse period is monitored until a predetermined period is reached. At this point, the plug is removed and an electrical brake (short circuit) is applied to the motor to bring the lens to a rest at the destination focus position.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.