light metering device with detector matrix and mean value detection
US4929824A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 24, 1989 |
| Grant date | May 29, 1990 |
| Priority date | — |
| Expiry date | Feb 24, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/71
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A light metering device includes a light detecting number having a plurality of light detecting elements arranged in a matrix for detecting brightness of smaller divisions into which a whole image field is divided, respectively, to define a plurality of light metering areas different in area in an image field so as to contain a smaller light metering area within a larger light metering area, and a calculating member for obtaining a mean brightness value of each light metering area by calculating an arithmetic mean value of the outputs from the light detecting elements defining each light metering area. The difference of mean brightness values of two adjacent light metering areas is compared with a predetermined critical mean brightness value to determine that lighting condition under which a subject exists is ordinary or unusual.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.