Television – Camera – system and detail – Camera image stabilization
Reexamination Certificate
1998-03-11
2002-11-26
Moe, Aung S. (Department: 2612)
Television
Camera, system and detail
Camera image stabilization
C348S208500
Reexamination Certificate
active
06486910
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus having an image blur correcting function for use in a video camera, a digital still camera or the like.
2. Related Background Art
Image pickup apparatuses (cameras) having a solid state image pickup element such as CCD on an imaging plane, such as video cameras and digital cameras, have heretofore been generalized. There are various sizes of image pickup elements such as CCD's used in these image pickup apparatuses, and generally, as the number of pixels is increased, the size of the CCD becomes larger, and correspondingly, the cost increases. From these conditions, what is called ¼ inch size, in which the diagonal length is in the order of 4 mm, or what is called ⅓ inch size, in which the diagonal length is in the order of 6 mm, is often conventionally used. Also the number of pixels of these CCD's is generally 300,000 to 400,000.
Thus, the image size of these image pickup apparatuses is small compared with the 43 mm diagonal of a 135 film silver halide camera. Therefore, in lenses of the same angle of view, great downsizing is generally possible relative to the lenses of 135 film cameras. In fact, in video cameras using a CCD of ¼ inch, a zoom lens having a zoom ratio of 10 and having a full length in the order of 50 mm is popular.
However, when such a zoom lens is mounted on a compact and light-weight video camera or digital still camera, there arises the problem that particularly in photographing wherein the focal length is set to a relatively long focus side, it is difficult due to hand vibration to obtain a stable image field. From such circumstances, various hand vibration preventing apparatuses have heretofore been proposed.
If a vibration preventing apparatus of this kind is used, not only the harmful vibration of the image field due to such hand vibration will be eliminated, but also a great effect will of course be achieved under such circumstances that in case of photographing from a ship or an automobile, harmful vibration cannot be eliminated even if a tripod is used.
The vibration preventing apparatus of this kind is provided with at least vibration detection means for detecting vibration, and blur correction means for effecting any correction in conformity with the information of the detected vibration so that blur may not occur as the image field.
As the vibration detection means, there are known, for example, an angular acceleration meter, an angular velocity meter, an angular displacement meter, etc. Also as the blur correction means, there are known optical means using a variable apex-angle prism or using the effect of shifting a part of a photo-taking optical system in a plane perpendicular to a photo-taking optical axis to bend the photo-taking optical axis as a result, and electronic means for sequentially changing (pursuing), in a video camera designed to cut out an area actually used as an image field from obtained image pickup image field information, the cutting-out position to a position in which vibration is corrected. However, the latter case is a correcting method among continuous image fields in a moving picture, and is not effective as the correction means in the case of a still picture.
Generally, optical correction means is capable of effecting correction to a vibration within an angle determined as the vibration correction angle of a camera irrespective of the focal length of the lens thereof, and accordingly, even when the focal length of a zoom lens on the telephoto side (the long focal length side) thereof is long, it is possible to have the capability of eliminating any vibration which poses no problem in practical use.
FIGS. 11A
,
11
B and
11
C of the accompanying drawings illustrate the relation between the focal length and the vibration angle of a camera in the prior art at an object position on the image field. In
FIG. 11A
, the optical axis of the lens when the camera is at a position indicated by
112
is
113
and thus, the face of a person
111
which is an object is caught substantially at the center of the image field. Let it be assumed that from this state, the camera has been rotated through a degrees by hand vibration. The position of the camera at this time is indicated by
114
and the optical axis is indicated by
115
.
FIGS. 11B and 11C
show the position of the image field in this camera position indicated by
112
and
114
,
FIG. 11C
shows the state of a zoom lens at the telephoto end (the end of the long focal length side), and
FIG. 11B
shows the state of the zoom lens at the wide end (the end of the short focal length side). The reference numeral
116
designates an object in the image field, the reference numerals
117
and
119
denote the respective image fields when the camera position is
112
, and the reference numerals
118
and
120
designate the respective image fields when the camera position is
114
.
As is apparent from
FIGS. 11A
to
11
C, even if the camera vibration is of the same a degrees, the harm is greater as the vibration on the image field as a matter of course when the focal length of the lens is long. Accordingly, if it is combined with a lens having long focal length particularly on the telephoto side, the effect thereof is remarkable.
FIGS. 12A
to
12
C,
13
A,
13
B,
14
and
15
of the accompanying drawings show a construction using a variable apex-angle prism as an example of the blur correction means according to the prior art.
FIGS. 12A
to
12
C show the construction of the variable apex-angle prism itself. In these figures, the reference numerals
121
and
123
designate glass plates, and the reference numeral
127
denotes a bellows portion made of a material such as polyethylene. Transparent liquid
122
such as silicon oil is enveloped in the interior surrounded by the glass plates
123
and the bellows
127
. In
FIG. 12B
, the two glass plates
121
and
123
are in a parallel state, and the angle of incidence and the angle of emergence of the ray of light of the variable apex-angle prism in this case are equal to each other. On the other hand, when as shown in
FIGS. 12A and 12C
, the glass plates have angles with respect to each other, the ray of light is bent at a certain angle as indicated by a ray of light
124
in
FIG. 12A and a
ray of light
126
in FIG.
12
C.
Accordingly, vibration can be eliminated by controlling the angle of the variable apex-angle prism provided in front of a lens so that when the camera is inclined by a cause such as hand vibration, the ray of light may be bent by an amount corresponding to the angle of the inclination.
FIGS. 13A and 13B
show such state, and in
FIG. 13A
, assuming that the variable apex-angle prism becomes parallel and the ray of light catches the head of the object, there is shown a state in which by a correction for driving the variable apex-angle prism for a vibration of a degrees as shown in
FIG. 13B
to thereby bend the ray of light, the photo-taking optical axis still continues to catch the head of the object again in this case.
FIG. 14
shows an example of the actual construction of a variable apex-angle prism unit including a variable apex-angle prism and an actuator portion for driving it, and an apex-angle sensor for detecting an angle state. Actual vibrations appear in all directions and therefore, the front glass surface and rear glass surface of the variable apex-angle prism are designed to be rotatable with directions which are 90° out of phase with each other as a rotational axis. Also, here, suffixes a and b indicate respective constituents in the two directions of rotation, and the constituents given the same reference numerals are entirely the same in function. Accordingly, description will hereinafter be made with the suffixes a and b omitted. The parts on the b side are partially not shown.
In
FIG. 14
, the reference numeral
141
designates a variable apex-angle prism comprising glass
121
,
123
, a bellows portion
127
, a liquid, etc. The glass plates
121
and
123
a
Azusawa Katsumi
Kaneda Naoya
Noguchi Kazuhiro
Okada Tadanori
Fitzpatrick ,Cella, Harper & Scinto
Moe Aung S.
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