Photography – With exposure objective focusing means – focusing aid – or... – Having pursuit mode
Reexamination Certificate
2000-03-08
2001-10-30
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Having pursuit mode
C396S104000, C396S123000
Reexamination Certificate
active
06311019
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-059997, filed Mar. 8, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an automatic focus adjusting system that can be applied to a camera or the like, and relates, more particularly, to an automatic focus adjusting apparatus and an automatic focus adjusting method capable of adjusting a focus of a moving subject.
Among techniques developed in recent years for a focus adjusting of an optical apparatus, there has been disclosed in U.S. Pat. No. 5,208,625, for example, a technique for detecting a move of an image of an image picked-up subject on a line sensor in an example of an automatic focusing apparatus having a focus detector based on a TTL phase difference detecting system.
In a camera built in with such an automatic focusing apparatus, it is judged whether or not an image picked-up subject has moved during a predetermined period of time, based on an image picked-up position of the subject at a certain time and an image position of the subject after a lapse of the predetermined period of time. When it is judged that the subject has moved during this period, the focus of the moved subject is adjusted to a correct focus based on a speed at which the subject moved.
This focus adjustment is what is called a “moving body correction” that is carried out as follows. When a move speed of an image of the subject on the line sensor is higher than a speed of a predetermined value when the subject has moved, it is judged that the subject is a moving subject, that is a moving body. Then, an image screen position of the subject at the time of starting an exposure is predicted based on a release time lag.
According to the above-described prior-art automatic focus adjusting apparatus, however, an obtained image of the subject may have deviated from the line sensor, when the subject has moved up and down or when the camera has moved due to a touch on the camera by hand or the like.
Accordingly, there may be a low correlation between image positions of the subject during a predetermined period of time, and thus there arises a situation where it is not possible to accurately detect the moving body.
As a result, there may be a case where a moving body is regarded as a stationary body, and the image of the moving body is not focused completely, thus producing a blurred picture.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic focus adjusting apparatus capable of improving the precision of focus adjustment of a moving subject.
It is another object of the present invention to provide an automatic focus adjusting method capable of improving the precision of focus adjustment of a moving subject.
In order to achieve the above objects, according to one aspect of the present invention, there is provided an automatic focus adjusting apparatus comprising:
image move-amount detecting means for detecting, for each of a pair of images of a subject divided in a predetermined direction, image positions of the subject in an image-divided direction and in a direction approximately orthogonal with this image-divided direction respectively on photoelectric conversion elements at mutually different first and second times respectively, and for obtaining move amounts of the images of the subject in the image-divided direction based on a result of this detection;
image position predicting means for predicting an image position of the subject in an image-divided direction at a third time different from the first and second times, based on an output from the image move-amount detecting means; and
control means for carrying out a focus adjustment so that the image of the subject is in focus at the third time, based on an output from the image position predicting means.
Further, according to another aspect of the invention, there is provided an automatic focus adjusting apparatus comprising:
photoelectric conversion means having, in at least a predetermined area, a plurality of light receiving elements in a two-dimensional array for receiving light beams respectively of a pair of images of a subject formed by a pair of light beams arrayed in a predetermined direction, from out of light beams of the subject;
two-image distance calculating means for calculating a distance between the pair of images of the subject, based on an output of the pair of images from the photoelectric conversion means;
predicting means for predicting a distance between the two images at a third time, based on two-image distances at a first time and a second time respectively, by repeatedly operating the two-image distance calculating means, wherein the first time, the second time and third time are different from each other;
control means for outputting a lens driving signal based on an output from the predicting means, when a predicted value based on a calculation by the two-image distance calculating means does not meet a predetermined condition and also when the predicted value meets the predetermined condition as a result of carrying out a signal processing again by the two-image distance calculating means based on a signal from a changed light-receiving area positioned in a direction approximately orthogonal with the pair of light beams arrayed in the predetermined direction in the photoelectric conversion means; and
Lens-driving means for driving an image pickup lens to focus the subject at the third time based on a lens-driving signal from the control means.
Further, according to still another aspect of the invention, there is provided an automatic focus adjusting apparatus for adjusting a focus of an image pickup lens so as to focus an image of an image picked-up subject positioned in a detecting area in a predetermined longitudinal direction within a photographing screen, the automatic focus adjusting apparatus comprising:
predicting means for predicting by calculation based on a result of a repeated detection of a focus;
lens driving means for driving the image pickup lens based on a prediction so as to focus the subject at a certain point of time in future, according to a result of the predict calculation conducted by the predicting means; and
control means for prohibiting the lens driving means from driving the image pickup lens based on a prediction when it is judged that there is a low level of reliability in the process of predict calculation by the predict calculating means, then for making the predict calculation means detect again the predict calculation by shifting the detection area to a direction approximately orthogonal with the longitudinal direction, and for making the lens driving means drive the image pickup lens when it is judged that there is a reasonable level of reliability in the focus detection.
Further, according to still another aspect of the invention, there is provided an automatic focus adjusting apparatus comprising:
image dividing means for dividing an image of an image picked-up subject into a pair of images;
first and second groups of photoelectric conversion elements for receiving respectively light beams of the pair of images divided by the image dividing means;
image move-amount detecting means for obtaining move amounts of images of the subject, for each of the pair of images divided by the image dividing means, based on image positions of the subject on the first and second groups of photoelectric conversion elements at mutually different first and second times;
detection area shifting means for shifting an image detection area of the subject detected by the image move-amount-detecting means, to a direction approximately orthogonal with a direction in which the image is divided;
image position predicting means for predicting positions of the images of the subject at a third time different from the first and second times, based on an output from the image move-amount detecting means; and
lens-driving means for driving
Olympus Optical Co,. Ltd.
Perkey W. B.
Pokotylo John C.
Straub & Pokotylo
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