Television – Camera – system and detail – Camera image stabilization
Reexamination Certificate
1997-11-18
2002-02-05
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Camera image stabilization
C396S055000
Reexamination Certificate
active
06344876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image blur preventing apparatus for preventing image blur caused by hand vibration or the like in a camera, an optical apparatus or the like.
2. Related Background Art
The construction of the essential portions of an example of a camera provided with a fluctuation preventing system is shown in
FIG. 21
of the accompanying drawings. In
FIG. 21
, a CPU
301
in a camera body
300
governs the control of the whole camera, focus control and fluctuation preventing control. Focus control and fluctuation preventing control will hereinafter be described briefly.
The case of focus control will first be described. Incident light from an object entering through a focusing lens
306
, a main photographing lens
305
and a fluctuation correction lens
304
is imaged on an image sensor
303
through a main mirror
307
, an AF sub-mirror
308
and a field lens
309
. The image formed on this image sensor
303
comprises two kinds of light beams passing through the different optical paths of the photographing optical system
305
by the conventional so-called pupil division system, and the defocus amount relative to a film surface
311
is detected from the amount of relative deviation of these two images on the image sensor
303
, and the focusing lens
306
is moved in the direction of the optical axis thereof in accordance with this defocus amount to thereby realize focus control.
Description will now be made of a case where fluctuation correction control is effected. An image blur correction amount is calculated from the combination of a fluctuation signal output from a mechanical sensor
302
such as an angular speed sensor such as a vibration gyro or other angular acceleration sensor (or a linear acceleration sensor) and an image blur signal output found from the amount of movement of the image data formed on the image sensor
303
through the aforementioned respective optical systems during different times, and on the basis of this image blur correction amount, the correction lens
304
is actually driven in real time as indicated by the arrow to thereby prevent the blur of an image on the film surface
311
(an image formed when the mirror
307
and the sub-mirror
308
are retracted in actual exposure).
In the case of the above-described example of the prior art, however, it is possible to introduce the data of the object image into the image sensor
303
through the intermediary of the mirror
307
and the sub-mirror
308
before exposure, but during exposure, the mirror
307
and the sub-mirror
308
are retracted as a matter of course and therefore, the output from the image sensor
303
becomes unusable. As a countermeasure for this, as disclosed in Japanese Patent Application Laid-Open No. 4-163534, there is a method of simply detecting the image blur speed immediately before exposure is started, and simply linearly approximating the blur at that speed. Although this method is effective when the movement of the object or the vibration of a photographer is taking place at an equal speed, the effect of this method cannot be said to be sufficient when fluctuation is taking place at a predetermined cycle or when the shutter speed of a camera used is low.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a blur preventing control apparatus which can calculate an optimum predicted blur waveform for image blur control during exposure by the operational state or the state of fluctuation of a camera.
One aspect of the invention is an image blur preventing apparatus applicable to a camera which has an image blur detecting device for detecting an image blur state, a predicting portion for predicting the image blur state after a predetermined point of time on the basis of the detection output of the image blur detecting device at the point of time, and forming a predicted image blur signal corresponding to the image blur state, an image blur preventing device for performing an image blur preventing operation in accordance with the predicted image blur signal obtained by the predicting portion, and a changing portion for changing the manner of the prediction by the predicting portion in accordance with the photographing operation state of the camera, whereby optimum prediction is effected in accordance with the state of the camera.
Another aspect of the invention is a signal forming apparatus for use for the image blur prevention of a camera and for forming a signal corresponding to an image blur state which has an image blur detecting device for detecting an image blur state, a predicting portion for predicting the image blur state after a predetermined point of time on the basis of the detection output of the image blur detecting device at the predetermined point of time, and forming a predicted image blur signal corresponding to the image blur state, and a changing portion for changing the manner of the prediction by the predicting portion in accordance with the photographing operation state of the camera, or a camera having such a signal forming apparatus, whereby optimum prediction is effected in accordance with the state of the camera.
REFERENCES:
patent: 5175580 (1992-12-01), Shiomi
patent: 5229603 (1993-07-01), Shiomi
patent: 5585884 (1996-12-01), Onuki
patent: 5589912 (1996-12-01), Shiomi
patent: 5615397 (1997-03-01), Shiomi et al.
patent: 5619030 (1997-04-01), Shiomi
patent: 5771405 (1998-06-01), Hirano
patent: 5933660 (1999-08-01), Shiomi
patent: 5953544 (1999-09-01), Kai et al.
patent: 6035133 (2000-03-01), Shiomi
patent: 6064825 (2000-05-01), Onuki
patent: 6067419 (2000-05-01), Shiomi
patent: 4-163534 (1992-06-01), None
Garber Wendy R.
Nguyen Luong
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