Camera with changeable focal length
US4831402A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 1988 |
| Grant date | May 16, 1989 |
| Priority date | — |
| Expiry date | May 31, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B3/10
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A camera includes a taking lens system changeable in focal length between at least a short focal length suitable for wide-angle photography and a long focal length suitable for telephotography. The lens system is held in a lens barrel which is axially displaced by means of a motor to change the lens system between at least the two different focal lengths. The camera is provided with a controller for sequentially controlling the motor to move the lens barrel in one axial direction so as to change the lens system to have one of the different focal lengths selected by a focal length selecting switch, to move the lens barrel in the opposite axial direction when the lens barrel does not reach a position wherein the taking lens system has the selected focal length in a predetermined time period, and to stop when the lens barrel reaches the position wherein the taking lens system has another one of the different focal lengths. For detecting the lens barrel at the axial position where the taking lens system has the different focal lengths, the camera is provided with a detector for detecting an unusual motion of the lens barrel in cooperation with the controller.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.