Zoom-type viewfinder device having a multi-sectioned viewfinder cam
US5678090A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 25, 1995 |
| Grant date | Oct 14, 1997 |
| Priority date | — |
| Expiry date | Jan 25, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/2101
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A zoom-type viewfinder device which has a multi-sectioned viewfinder cam which rotates in connection with the zooming of a photographic zoom lens. The viewfinder cam has a cam, with at least one cam bevel, which is divided into a first cam component and a second cam component. The first cam component and the second cam component are joined to connect the respective cam bevels to form a cam bevel which wraps more than once around of the cylinder of the viewfinder cam. As the viewfinder cam is manufactured in multiple segments, each segment can be removed from its forming die in the longitudinal direction of the viewfinder cam, thereby providing smooth zooming and a blur free viewfinder image. Also, the inclinations of cam bevels, which are formed on the viewfinder cam, can be made more gradual, which reduces the required driving force. Therefore, a more compact motor can be used, resulting in a more compact camera. Moreover, the power consumption required by the motor is reduced, increasing the life of the camera battery.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.