light metering device with detector matrix and mean value detection

A light metering device comprising:

• a plurality of light detecting elements arranged in a matrix to detect brightness of smaller divisions into which a whole image field is divided, respectively;
• means for defining a rectangular standard light metering area by selectively driving said light detecting elements contained in a corresponding rectangular area, defining a rectangular reference light metering area reduced in size depending from said standard light metering area, shifting said reduced reference light metering area in four ways so as to coincide one corner of said reduced reference light metering area with a corresponding corner of said standard light metering area one after another to detect a mean brightness value of said reduced reference light metering area shifted to each said corresponding corner of said standard light metering area, selecting one reduced reference light metering area having an extreme mean brightness value among said four-way shifted reduced reference light metering areas to determine it as another rectangular standard light metering area, and defining another rectangular reduced reference light metering area depending from said another standard light metering area;
• means for detecting a maximum brightness value of said respective standard light metering area;
• mean brightness detecting means for detecting a mean brightness value of said respective reference standard light metering area;
• means for comparing said difference of said mean brightness values of each two adjacent reference standard light metering areas with a determined or preselected value;
• and
• an exposure determining means for determining an exposure based on said mean brightness value of said another reference standard light metering area when said difference between said mean brightness values of said adjacent reference standard light metering areas converges said predetermined value.

A light metering device having a plurality of light detecting elements arranged in a matrix detect brightness of smaller divisions into which a whole image field is divided, respectively, said light metering device comprising:

• means for defining a rectangular standard light metering area by selectively driving said light detecting elements contained in a corresponding rectangular area, defining a rectangular reference light metering area reduced in size depending from said standard light metering area, shifting said reduced reference light metering area in four ways so as to coincide one corner of said reduced reference light metering area with a corresponding corner of said standard light metering area one after another to detect a mean brightness value of said reduced reference light metering area shifted to each said corresponding corner of said standard light metering area, selecting one reduced reference light metering area having an extreme mean brightness value among said four-way shifted reduced reference light metering areas to determine it as another rectangular standard light metering area, and defining another rectangular reduced reference light metering area depending from said another standard light metering area;
• means for detecting a maximum brightness value of said respective standard light metering area;
• means for comparing said difference of the maximum brightness values of said standard light metering areas and a maximum brightness value of a whole maximum light metering area corresponding a whole image field with a determined value;
• and
• exposure determining means for determining a proper exposure based on data of brightness of a smaller one of said standard light metering areas when said difference of said maximum brightness values of said standard light metering area relative to said maximum brightness value of a light metering area corresponding to said whole image field becomes larger than a predetermined brightness value.