Zoom lens driving apparatus
US4991944A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1988 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | Dec 27, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/673
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A zoom lens driving apparatus always detects a position of an image magnification varying lens section, and drives the image magnification varying lens section in accordance with a preset relationship between the position of the image magnification varying lens section and a zoom driving speed in such a manner that the driving speed becomes higher on one side, where the focal length of the zoom lens corresponding to the position of the image magnification varying lens section is small, than on another side where the focal length is large. Accordingly, the amount of focal shift, which in the zoom lens of the inner focusing system would otherwise abruptly increase with increasing focal length, is significantly suppressed, so that an auto focus adjusting mechanism or a focus correcting device effective during zooming, provided in the zoom lens, can function satisfactorily as to follow the focal shift of the zoom lens, whereby the lens control of a superior response can always be achieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.