1986-09-19
1987-09-22
Perkey, W. B.
G03B 7095
Patent
active
046951504
ABSTRACT:
A diaphragm-control apparatus for controlling stopping-down of an aperture of a photographing lens for a camera to obtain a desired aperture value includes light metering means for detecting an intensity of light reflected by an object to be photographed and transmitted through the aperture and sequentially generating electrical signals each corresponding to a detected light intensity, memory means for storing a predetermined number of electrical signals, storing means for sequentially storing the electrical signals in the memory means. The storing means is adapted to store the electrical signal in place of an oldest electrical signal stored in the memory means. The apparatus further includes operating means for sequentially calculating changing velocities represented by the electrical signals during stopping-down according to the predetermined number of electrical signals stored in the memory means. The operating means is adapted to sequentially calculate a predicted electrical signal to be produced by the light metering means after a lapse of a predetermined period of time from a time corresponding to a newest electrical signal stored in the memory means, according to a corresponding one of calculated changing velocities, and stopping means for detecting that a value represented by the predicted electrical signal calculated by the operating means has a predetermined relationship with the desired aperture value, and for interrupting the stopping-down.
REFERENCES:
patent: 2307948 (1943-08-01), Phillips
patent: 4269497 (1981-03-01), Ishizaka et al.
patent: 4288150 (1981-09-01), Ogasawara
patent: 4307948 (1981-12-01), Kitamura et al.
patent: 4322145 (1982-03-01), Yamada et al.
patent: 4396271 (1983-08-01), Hiraike
patent: 4600289 (1986-07-01), Maida et al.
Nippon Kogaku K. K.
Perkey W. B.
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