Zoom lens focus control device for film video player
US4920419A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 31, 1988 |
| Grant date | Apr 24, 1990 |
| Priority date | — |
| Expiry date | May 31, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/282
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A device (10) controls the focus in a film video player (11) for projection of at least a portion of a film image (F) onto a sensor (16) that generates a corresponding video signal from the sensor image. The film video player (11) has a fixed focal length lens (15) and includes a zoom motor (25) and related elements for changing the magnification of the sensor image with respect to the film image, sensor motor (34) and related elements for adjusting the focus of the sensor image, and a microprocessor (40) and related elements for determining the necessary adjustment to and for controlling the sensor motor to maintain the focus of the sensor image at any selected magnification without cam surfaces. Device (10) determines actual lens focal length upon power-up, eliminating focus variances due to manufacturing and installation, and maintains apparent zoom rate constant throughout the selected range of magnifications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.