Photography – With exposure objective focusing means – focusing aid – or... – Having in-focus threshold adjustable
Patent
1995-06-29
1997-05-06
Metjahic, Safet
Photography
With exposure objective focusing means, focusing aid, or...
Having in-focus threshold adjustable
396 95, G03B 300, G03B 310
Patent
active
056280360
ABSTRACT:
A focus adjustment device that eliminates unnecessary driving of a shooting lens after the shooting lens has already been driven near to an in-focus position. In a focus adjustment device, information related to the defocus amount of the shooting lens is detected based on output signals corresponding to the light intensity distribution of a object image from a pair of photo-electric conversion arrays. The focus adjustment device includes a focus detection circuit to determine the confidence level of the detected information based on predetermined determination criteria and a lens driving device to drive the shooting lens based on the detected information when the information of the focus detection device is accepted as having a sufficient confidence level. However, to prevent erroneous driving of the lens, such as when the object moves out of a focusing field or when the object reverses direction, the probability of rejecting the information of the focus detection on the basis of an insufficient confidence level increases. This occurs when information indicating that the occurrence of a defocus amount exceeding a predetermined range is detected by the focus detection circuit after the shooting lens has previously been determined to have been driven within permissible parameters of an in-focus position.
REFERENCES:
patent: 4855776 (1989-08-01), Akashi
patent: 5227828 (1993-07-01), Kirigaya
patent: 5448051 (1995-09-01), Yamano
patent: 5457513 (1995-10-01), Uenaka
patent: 5502537 (1996-03-01), Utagawa
patent: 5517275 (1996-05-01), Kusaka et al.
Ozawa Masamitsu
Uchiyama Shigeyuki
Watanabe Toshimi
Metjahic Safet
Nelson Eric
Nikon Corporation
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