Photography – Camera shake sensing – With photoarray
Reexamination Certificate
2000-05-25
2001-05-01
Perkey, W. B. (Department: 2851)
Photography
Camera shake sensing
With photoarray
Reexamination Certificate
active
06226459
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus having a driven member and a drive controller therefor such as a camera having an image-blur correcting function.
2. Description of the Prior Art
To prevent unsuccessful photographing due to hand shakes, cameras having an image-blur correcting function have been developed. Today, many cameras come equipped with a zoom lens with an increasingly high magnification as their standard lens, and, as a result, photographing with long focal lengths is now considerably easy. However, this inevitably makes the effect of hand shakes felt more strongly than ever before, and therefore image-blur correction is a desirable function in cameras today; in fact, in movie video cameras, it is indispensable.
Conventionally, image-blur correction in a camera is achieved as follows. The light from an object is directed into an image-blur detecting optical system, where the light is passed through an imaging lens and is then received by an image-blur detecting sensor that is realized with a photoelectric conversion device such as CCD (charge-coupled device). When a hand shake occurs, this sensor detects the resulting image blur. Then, in accordance with the amount and direction of the detected image blur, an image-blur correcting lens unit driving system drives an image-blur correcting lens unit to be decentered in a direction perpendicular to the optical axis of the taking optical system in such a way that the image blur is canceled out. As a result, the image of the object is kept in the same position on the film throughout exposure.
However, to achieve image-blur correction as described above, a camera needs to be equipped with an image-blur detecting optical system and an image-blur detecting sensor, both of which require extra space inside the camera. This is inconvenient especially in compact cameras, because providing them with an image-blur correcting function results in making them larger and heavier, quite contrary to what is expected of such cameras.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an apparatus having a driven member whose position can be controlled with high accuracy.
Another object of the present invention is to provide a compact and lightweight camera having an image-blur correcting function that can be realized without securing unduly large space for it inside the camera.
To achieve the first object, according to one aspect of the present invention, an apparatus is provided with a member to be driven; an actuator that in response to a pulse signal drives said to-be-driven member to move by an amount proportional to a given number of pulses; a position detector that detects the position of said to-be-driven member in predetermined detection steps; and a controller that determines in steps smaller than said predetermined detection steps a target position up to which said to-be-driven member is to be moved, controls said actuator up to a detection-step position immediately before the target position by closed-loop control in accordance with a detection result from said detector, and controls said actuator from that detection-step position to the target position by open-loop control.
To achieve the second object, according to another aspect of the present invention, in a camera having an image-blur correcting function, an optical system is provided with an apparatus as noted above.
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Hamada Masataka
Hayashi Kohtaro
Kanbara Tetsuro
Yukawa Kazuhiko
Burns Doane , Swecker, Mathis LLP
Minolta Co. , Ltd.
Perkey W. B.
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