Television – Camera – system and detail – Swing driven
Reexamination Certificate
1995-02-27
2004-05-11
Tran, Thai (Department: 2615)
Television
Camera, system and detail
Swing driven
Reexamination Certificate
active
06734903
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image sensing apparatus and, more particularly, to a high-resolution image sensing apparatus using an image sensor such as a charge coupled device (CCD).
A recent advance of image sensors such as a charge coupled device (CCD) has achieved a high image quality, a low price, and a small size of image sensing apparatuses, e.g., household compact video cameras and still video cameras. Consequently, a satisfactory image quality can be obtained by a television standard of, e.g., NTSC. In addition, camera shake correction is currently performed in video cameras and the like, and this further improves the image quality of dynamic images.
A camera shake is a phenomenon in which photographed images move vertically or horizontally while a user is performing photographing by holding a video camera in his or her hands, since the hands or the body of the user slightly moves independently of the user's intention. Images thus photographed give a viewer a considerable uncomfortableness when reproduced on a television monitor or the like.
To avoid this camera shake phenomenon, conventional video cameras make use of, e.g., a variable angle prism (to be referred to as a “VAP” hereinafter).
A practical example of an arrangement of a conventional image sensing apparatus including a VAP for camera shake correction will be described below with reference to FIG.
15
.
In
FIG. 15
, a VAP
104
is constituted by coupling two glass plates
104
a
and
104
b
via a bellows-like spring member
104
c
and sealing an optically transparent liquid
104
d
in the space surrounded by the two glass plates
104
a
and
104
b
and the spring member
104
c
. Shafts
104
e
and
104
f
provided in the glass plates
104
a
and
104
b
are connected to an actuator
103
for horizontal driving and an actuator
108
for vertical driving, respectively. Therefore, the glass plate
104
a
is rotated horizontally, and the glass plate
104
b
is rotated vertically.
Note that the VAP
104
is described in Japanese Patent Laid-Open No. 2-12518 and so a detailed description thereof will be omitted.
A horizontal angular velocity sensor
101
detects an angular velocity caused by a horizontal motion of the image sensing apparatus resulting from a camera shake or the like. A control unit
102
performs an arithmetic operation for the detection signal from the angular velocity sensor
101
such that this horizontal motion of the image sensing apparatus is corrected, and detects and supplies an acceleration component to the actuator
103
. This actuator
103
drives the glass plate
104
a
of the VAP
104
horizontally.
The rotational angle of the glass plate
104
a
which can be horizontally rotated by the actuator
103
is detected by an angle sensor
105
. The control unit
102
performs an arithmetic operation for this detected rotational angle and supplies the result to the actuator
103
.
A vertical angular velocity sensor
106
detects an angular velocity caused by a vertical motion of the image sensing apparatus resulting from a camera shake or the like. A control unit
107
performs an arithmetic operation for the detection signal from the angular velocity sensor
106
such that this vertical motion of the image sensing apparatus is corrected, and detects and supplies an acceleration component to the actuator
108
. This actuator
108
drives the glass plate
104
b
of the VAP
104
vertically.
The rotational angle of the glass plate
104
b
which can be vertically rotated by the actuator
108
is detected by an angle sensor
109
. The control unit
107
performs an arithmetic operation for this detected rotational angle and supplies the result to the actuator
108
.
An image sensing optical system
110
forms an image of an object to be photographed on an image sensor
111
. This image sensor
111
is constituted by, e.g., a CCD. A two dimensional solid state CCD is used in conventional image sensing apparatuses such as video cameras. An output from the image sensor
111
is output to a recording apparatus or a television monitor through a signal processing circuit (not shown).
In the conventional image sensing apparatus with the above arrangement, the horizontal and vertical angular velocities caused by a camera shake are detected. On the basis of the angular velocities detected, the actuators move the VAP horizontally and vertically to refract incident light, thereby performing control such that the image of an object to be photographed does not move on the image sensing plane of the image sensor. Consequently, the camera shake is corrected.
On the other hand, with recent spread of image sensing apparatuses, an increasing demand has arisen for a higher image quality. To meet this demand, it is being attempted to increase the number of pixels of an image sensor such as a CCD in an image sensing apparatus or to develop a high-speed I/O apparatus or an image information compressing/decoding apparatus.
For example, the number of pixels of a conventional two-dimensional solid state CCD is normally 400,000, and the number of pixels of even a high-resolution CCD is at most 2,000,000. These pixel numbers currently available are unsatisfactory to obtain a sufficient resolution necessary for images, hard copies, and computer graphics to be displayed on large screens.
The following methods, therefore, are disclosed as a method of realizing a high image quality with a limited number of pixels of an image sensor.
(1) A method in which an image of an object to be photographed is divided by a prism and photographed by a plurality of image sensors, as found in some presently available video camera recorders.
(2) A method as proposed in, e.g., Japanese Patent Laid-Open No. 60-250789, in which an image region of a photographing optical system is split by, e.g., a secondary imaging optical system, and the individual split regions are photographed by a plurality of image sensors and then synthesized.
(3) A method of pixel shift proposed in, e.g., Japanese Patent Publication Nos. 50-13052, 59-18909, and 59-43035. In this method, an element for splitting a light beam, such as a dichroic mirror or a half mirror, is arranged on the image plane side of an image sensing optical system, and a plurality of area sensors are arranged to be shifted from each other by an amount corresponding to a half pixel pitch or smaller. In this method it is possible to obtain, from a plurality of resulting images, information containing pixels in a number larger than the number of pixels of the area sensors. Also, “Highvision ⅔-inch compact CCD camera using dual green method” in Television Society Magazine, “Image Information Engineering and Broadcasting Technology”, Vol. 47, No. 2, 1993 has reported a method in which two of three CCDs for receiving separated light beams from a trichromatic separation prism are arranged such that their pixels are shifted from each other. In this method an object to be photographed is photographed with this pixel-shifted arrangement.
(4) Japanese Patent Publication No. 57-31701 or 64-863 has disclosed a method by which a pixel shift is performed by moving the position of incident light to an image sensor relative to the image sensor in synchronism with the read timing of an output electrical signal from the sensor. This is accomplished by, e.g., inserting a birefringence polarizing element into a photographing optical system and controlling the element. By periodically photographing the resulting images, it is possible to obtain information containing pixels in a number larger than the number of pixels of the image sensor. Research and development of this pixel shifting method have been made extensively to date.
As discussed above, the camera shake preventing function and the resolution increasing function have been developed in conventional image sensing apparatuses. Unfortunately, in these conventional image sensing apparatuses the camera shake preventing function and the resolution increasing function are independent of each other. Therefore, the conven
Fujiwara Akihiro
Ogura Shigeo
Takeda Nobuhiro
Wada Hiroyuki
Canon Kabushiki Kaisha
Morgan & Finnegan L.L.P.
Onuaku Christopher
Tran Thai
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