Range finding automatic focusing system employing a rotatable transparent plate and a half-split light receiving element
US4740676A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1986 |
| Grant date | Apr 26, 1988 |
| Priority date | — |
| Expiry date | May 1, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/32
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An automatic focusing apparatus comprises a light emitting element emitting a beam of electromagnetic radiation directed toward a subject through a light projecting lens, a light receiving element receiving a beam spot reflected from the subject and passing through a light receiving lens, and a parallel-surface transparent plate disposed rotatably between the light receiving lens and the light receiving element. The parallel-surface transparent plate is rotated in interlocking relation with linear movement of an optical lens moving together with movement of a focus ring, thereby automatically attaining the focus by ceasing the movement of the lens optical system as soon as the output signal of the light receiving element attains a predetermined level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.