Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
1997-10-06
2001-08-28
Mathews, Alan A. (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
Reexamination Certificate
active
06282376
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image stabilizing device for preventing the image blur of an optical instrument such as a camera resulting from hand vibration.
2. Related Background Art
In recent optical instruments such as cameras, almost all of functions necessary for photographing such as the determination of exposure and focusing are automatized and failure attributable to the photographing function has become very rare, and recently, the development of cameras in which failure in photographing attributable to any other factor than the photographing function, for example, the blur of a photographed image caused by vibration such as hand vibration, is automatically suppressed has been put forward.
Usually, to prevent vibration from occurring to a photographed image even if hand vibration occurs with the release of a camera shutter, it is necessary that means capable of detecting the vibration of the camera and properly accomplishing the correction of image blur on the basis of the detected information, i.e., an image stabilizing device, be carried on the camera.
FIG. 18
of the accompanying drawings shows in schematic block diagram an example of an image stabilizing device according to the prior art. First describing the vibration detecting means, this is constructed as optical angle deviation detecting means. That is, a case
701
enclosing therein liquid whose viscosity or the like is suitably selected and provided so as to move with a camera (or a lens barrel) has therein a mechanism supporting a float
702
freely rotatable about a rotary shaft
703
, and assuming, for example, that vibration has occurred to the camera (lens barrel) and this camera has rotated by &thgr;
in
in relative to the coordinates system of absolute space, the case
701
moves with the camera. In contrast, the liquid in the case maintains its stationary state relative to the absolute space by its inertia force. Thus, the float
702
and the case
701
have rotated by &thgr;
in
in corresponding to said vibration.
So, by light from a light emitting element
706
fixedly provided on the camera (lens barrel) being reflected by the float
702
and the reflected light being received by a light receiving element
705
, the angle deviation of said vibration can be detected in a position detecting circuit
704
connected to the light receiving element
705
.
On the other hand, description will now be made of a mechanism for making an image on the image plane apparently stationary. In the example of the prior art shown in
FIG. 18
, liquid having a predetermined refractive index is enclosed in an accordion-shaped container formed by connecting two transparent plates together by bellows, thereby constituting a variable vertical angle prism
707
, which is used as optic axis eccentricity means. The transparent plate on the object side is suitably tilted relative to the fixed transparent plate adjacent to a photo-taking lens
708
by an actuator
713
which is a solenoid so that the photographing optic axis can be changed. That is, by the transparent plate on the object side of the variable vertical angle prism
707
rotating by &thgr;
out
, a photographing optical path passing through the photo-taking lens
708
to the surface
709
of film rotates relative to the optic axis in proportion to said Gout and in accordance with a proportion constant determined by the refractive index of the enclosed liquid.
As described above, in the camera of
FIG. 18
, vibration occurring to the camera is detected by the optical angle deviation detecting means using the rotatable float
702
and the vertical angle of the variable vertical angle prism
707
is varied by an angle corresponding to the detected vibration, whereby even when the camera vibrates, the incident light from an object can always be directed to the same position on the surface
709
of the film, thereby suppressing the blur of a photographed image.
In the prior-art device of
FIG. 18
, the actual state of the angle deviation &thgr;
out
effected by the variable vertical angle prism
707
is detected by a position detecting circuit
712
disposed near the variable vertical angle prism
707
, and an amount of output indicative of said angle deviation &thgr;
out
is subtracted from a signal indicative of the angle &thgr;
in
which is the output of the position detecting circuit
704
detected as the vibration of the camera, and said subtracted output is amplified by an amplifier circuit
714
and thereafter is input to a driver circuit
716
through a phase compensator circuit
715
.
Accordingly, the driving of the actuator
713
is feedback-controlled thereby and accurate image stabilization control is realized.
Now, in the image stabilizing device described above with reference to
FIG. 18
, the starting or termination of the image stabilizing operation are effected, for example, by the ON/OFF of a manually operated switch extraneously operated which is designated by
720
in
FIG. 18
, and this forms means for actually starting or terminating the operation.
That is, the input from the angle deviation detecting means to the actuator
713
is effected by the ON/OFF of the manually operated switch
720
.
In such a construction, when the switch
720
is closed when inputting the detection output from the above-described optical angle deviation detecting means to the driver
716
of the variable vertical angle prism (that is, starting the image stabilization), the signal indicative of the vibrated state which is detected by the angle deviation detecting means is intactly input to the driver
716
.
However, such control, although not said to be unsuitable as a device which satisfies the image stabilizing function, has led to the problem that it results in a system inconvenient for use when viewed from the viewpoint of the use of the camera carrying such device thereon.
Considering, for example, a case where the switch
720
is closed with the position detection signal from the angle deviation detecting means being greatly off the usual central position and image stabilization control is started, the transparent plate on the object side of the variable vertical angle prism
707
is suddenly displaced from its inclined state to its parallel state.
This results in a sudden change in the optical path, and in a camera of a type such as TTL in which an object is seen through a viewfinder and a photo-taking optical system, there occurs the discontinuity (so-called skip) of the viewfinder image, and this has led to the disadvantage of giving the photographer a great feeling of physical disorder.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-noted circumstances and intends to provide an image stabilizing device which is provided with vibration detecting means for detecting the vibrated state of an image, vibration compensating means responsive to said vibration detecting means to compensate for the vibration of the image, connecting means for substantially connecting said vibration detecting means to said vibration compensating means, and alleviating means for preventing said vibration compensating means from effecting sudden starting of an operation responding to said vibration detecting means during said connection by said connecting means and which eliminates the above-noted problem peculiar to the prior-art image stabilizing device and also eliminates the discontinuity of a viewfinder image or the like and does not give the user a reeling of physical disorder.
Other objects of the present invention will become apparent from the following detailed description of some specific embodiments of the invention.
REFERENCES:
patent: 4965619 (1990-10-01), Shikaumi et al.
patent: 5107293 (1992-04-01), Sekine et al.
Canon Kabushiki Kaisha
Mathews Alan A.
Robin Blecker & Daley
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