Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
2001-12-18
2004-03-09
Mahoney, Christopher (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
Reexamination Certificate
active
06704502
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image blur correction apparatus suitable for a image sensing device such as a silver halide camera and a video camera or an optical device such as a binocular.
In the field of photographing devices such as a silver halide camera and a video camera, conventionally, automatic and multi-functional arrangements for exposure setting, focus adjustment, and the like are in progress. This makes it possible to always perform a satisfactory photographing operation regardless of the photographing environment.
However, the image quality largely deteriorates due to a camera shake in fact. In recent years, therefore, various vibration correction apparatuses for correcting this camera shake are proposed and receiving a great deal of attention.
As for vibration correction apparatuses, their correction systems are roughly classified into optical correction and electrical correction using image processing, and detection systems are classified into physical vibration detection and detection by image processing using an image vector. Various combinations of these systems are proposed.
Optical vibration correction will be described below. An angular velocity detection means such as a vibration gyroscope is provided as a vibration detection means. A velocity signal output from the angular velocity sensor is integrated and converted into an angular displacement signal. An optical vibration correction means such as a variable angle prism (to be referred to as a VAP hereinafter) capable of changing the direction of optical axis is driven, thereby optically correcting the vibration.
Such an optical vibration correction apparatus has a feedback loop in which the VAP is driven in accordance with a vibration correction control signal for performing normal vibration correction, and simultaneously, the angular displacement of the VAP is detected to drive the VAP to a position corresponding to the control signal.
In the vibration correction apparatus using the optical/mechanical vibration correction means such as the above-mentioned VAP, however, a mechanical degradation such as shaft friction and element deformation is caused particularly by the temperature and time change of a mechanical movable portion. This may cause a deterioration in responsiveness (follow-up properties), which is not negligible in control of a relatively small vibration (e.g., when the optical axis is slightly (about 0.03 deg in an embodiment to be described later) displaced for polarization). In addition, variations in VAPs and their driving systems are large.
In the vibration correction apparatus using the VAP controlled by a servo mechanism, such a deterioration or variation in mechanical performance results in a disadvantage so that the central position for control shifts due to load variations such as a temperature and time change.
Additionally, the driving limit of the VAP disadvantageously varies because the elements change due to a temperature and time change, or the battery is consumed.
Furthermore, since variations in optical axis adjustment are large, the generated vibration cannot be completely absorbed by vibration correction only by adjustment using the offset of an output signal from a low-end one-chip microcomputer in some cases.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vibration correction apparatus which corrects a mechanical degradation such as shaft friction or element deformation, or a delay in response due to the temperature and time change of a movement correction means and simultaneously corrects variations due to a difference between individual driving systems, thereby always ensuring satisfactory response characteristics.
According to the present invention, the foregoing object is attained by providing a vibration correction apparatus comprising vibration detection means for detecting a vibration, movement correction means for correcting a movement of an image, which is caused by the vibration, on the basis of an output from the vibration detection means, and control means for detecting response characteristics of the movement correction means with respect to a predetermined driving signal and correcting driving characteristics of the movement correction means on the basis of a detection result.
In accordance with the present invention as described above, when the response characteristics of the movement correction means with respect to a test driving signal are detected, the offset is corrected so that a change in characteristics caused by a mechanical error such as shaft friction or element deformation caused by the temperature and time change can be corrected.
There is also provided a vibration correction apparatus comprising vibration detection means for detecting a vibration of an image sensing device main body, movement correction means for correcting a movement of an image, which is caused by the vibration, on the basis of an output from the vibration detection means, characteristic detection means for detecting response characteristics of the movement correction means with respect to a predetermined driving signal and calculating an offset between a detection result and a predetermined reference value, storage means for storing the offset calculated by the characteristic detection means and control means for correcting driving characteristics of the movement correction means on the basis of offset information stored in the storage means.
With the above arrangement, when the response characteristics of the movement correction means with respect to the test driving signal are detected, the offset to ideal response characteristics is detected, and the transfer characteristics are corrected. Since this offset information is stored and used for the subsequent control, the operation of the movement correction means is always performed with the optimum characteristics, and a change in characteristics due to a mechanical error such as shaft friction or element deformation caused by the temperature and time change is compensated.
Accordingly, it is another object of the present invention to provide a vibration correction apparatus and an optical device which simultaneously performs balance adjustment of the response characteristics between a plurality of optical systems of an optical apparatus such as a binocular to which the vibration correction apparatus is applied, thereby obtaining vibration correction characteristics while equalizing the characteristics of the optical systems.
According to the present invention, the foregoing object is attained by providing a vibration correction apparatus comprising first movement correction means for correcting a movement of an image which is caused by a vibration, second movement correction means for correcting the movement of said image, which is caused by the vibration and control means for detecting response characteristics of said first movement correction means with respect to a predetermined driving signal and response characteristics of said second movement correction means with respect to the driving signal, and correcting the driving characteristics of one of said first and second movement correction means such that the response characteristics of said first movement correction means are substantially equalized with those of said second movement correction means.
In accordance with the present invention as described above, the response characteristics of the first and second movement correction means can always be equally set, and balance adjustment between the response characteristics of the movement correction means can be performed. At the same time, a change in characteristics due to a mechanical error such as shaft friction or element deformation caused by the temperature and time change is corrected.
There is also provided an optical device comprising a first optical system having a movable portion for changing optical characteristics, first driving means for driving the first optical system, a second optical system having a movable portion
Canon Kabushiki Kaisha
Mahoney Christopher
Morgan & Finnegan L.L.P.
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