Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
2003-01-24
2004-08-17
Adams, Russell (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
C348S208130, C348S294000
Reexamination Certificate
active
06778767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shake correcting device, an image pickup apparatus, a shake correcting method, a program for performing, and a storage medium storing the program, and more particularly relates to a shake correcting device, an image pickup apparatus, a shake correcting method, a program for performing, and a storage medium storing the program, which are suitable for preventing such a phenomenon that white defects move around on a display screen of a camera or a video camera or the like having an electronic shake correcting unit mounted thereon.
2. Description of the Related Art
Conventional image stabilizing systems as employed in apparatuses such as video cameras include a type that detects shakes of the apparatus by an angular velocity sensor, uses an image pickup element, having more pixels than a standard image pickup element required by television broadcasting systems, and extracts preselected areas with the standard size of broadcasting systems from within the entire image pickup area of the image pickup element, according to shakes of the apparatus detected by the angular velocity sensor. A shake correcting device employing this type of image stabilizing system will be further described.
FIG. 8
is a schematic diagram showing an image of the image pickup area of an image pickup element. In the figure, reference numeral
601
designates the entire image pickup area of the image pickup element, and reference numerals
602
to
604
designate areas with the standard size of broadcasting systems. When performing no shake corrections, an area
603
positioned in the center of the entire image pickup area is extracted, selecting from the three areas,
602
to
604
, and thus a video image is output. When performing a correction, a video image is output, extracted from an area selected from the entire image pickup area
601
, but with a deviation, for example, to the area
602
or the area
604
, in order to remove a shake of the apparatus, according to a signal from a unit for detecting shakes, not shown. With regard to the position of an area to be extracted, there is no limitation as long as the area extracted lies within the entire area
601
, and the area can even be extracted from an arbitrary position within the entire area
601
.
FIG. 9
is a block diagram showing, as an conventional example, the configuration of an image pickup apparatus portion of a video camera that has a shake correcting device of the area extraction system, described above, as a shake correcting unit, using an angular velocity sensor as a shake detection unit. An image pickup apparatus having a shake correcting device mounted thereon will be described below with reference to FIG.
9
. In the figure, reference numeral
101
designates a lens unit, and reference numeral
102
designates a charge coupled device (CCD). A subject image is formed on the CCD
102
by the lens unit
101
, and then photoelectrically converted by the CCD
102
. The CCD
102
has more pixels than the standard CCDs required by broadcasting systems (for example, NTSC (National Television System Committee)). Reference numeral
104
designates a CCD drive circuit for driving the CCD
102
. The CCD drive circuit
104
is designed to be able to select lines with respect to the direction V (the number of lines) in
FIG. 8
, described above, from the lines in the entire image pickup area of the CCD
102
in order to extract an area for a final output, wherein the selection is made upon a control instruction from a microcomputer
919
for camera system control, described later.
The reference numeral
601
in
FIG. 8
, mentioned above, designates the entire image size, and the reference numerals
602
to
604
designate examples with the standard image size according to broadcasting systems. In
FIG. 8
, when the lines starting from ya+1, which is &Dgr;ya lines below the uppermost line, are effective for example, the &Dgr;ya lines are read at a high speed, and thereafter the lines from ya+1 line are read out in the same timing as the case of using a CCD with the standard size with respect to a vertical synchronizing signal. Then, the remaining &Dgr;yb lines are read out again at a high speed, thus practically extracting lines of the standard image size with respect to the direction V.
Upon a control instruction from the microcomputer
919
, the CCD drive circuit
104
controls the accumulating time of the signal charge in the CCD
102
, thereby implementing an electronic shutter. Specifically, a high speed shutter is implemented by setting the accumulating time of the signal charge in the CCD
102
short, and a slow shutter is implemented by setting the accumulating time, described above, long.
Reference numeral
103
designates an analog signal processing section that performs a predetermined process on signals obtained from the CCD
102
to generate analogue image pickup signals. Specific examples of the analog signal processing section
103
are a CDS (Co-related Double Sampling) circuit, and an AGC (Automatic Gain Control) circuit. Reference numeral
106
designates a line memory that can store a digital image pickup signal for one line at least by a memory control circuit
107
. Further, pixels can be read out from a predetermined address in the line memory
106
by the memory control circuit
107
. Reference numeral
105
designates a camera signal processing section that has a built-in A/D converter and performs processing of digital signals to generate final output video signals. A digital image pickup signal stored in the line memory
106
includes more pixels than the standard image size of the CCD
102
, keeping the large number of pixels. The memory control circuit
107
is designed to be able to select a top pixel to be read from the line memory
106
, and to read pixels for the standard image size, upon a control instruction from the microcomputer
919
, described in the following.
The microcomputer
919
performs control of the entire camera system including control of the CCD drive circuit
104
, exposure control, white-balance control, variable power lens control, auto focus control, image stabilizing control. However, in
FIG. 9
, only a portion of these functions associated with shake correction is shown for brevity. Shake detection is performed with respect to the two axes in the pitch (vertical) direction and the yaw (horizontal) direction. Since the same control is performed for the two axes,
FIG. 9
shows the control only for one direction. Reference numeral
111
designates an angular velocity sensor for detecting shakes of the camera. Reference numeral
112
designates a HPF (High Pass Filter) for cutting the DC component of angular velocity signals output from the angular velocity sensor
111
. Reference numeral
113
designates an amplifier for amplifying angular velocity signals detected by the angular velocity sensor
111
.
Reference numeral
114
designates an A/D converter incorporated into the microcomputer
919
, which converts angular velocity signals in the two directions, described above, into digital signals to become angular velocity data. Further, a HPF
115
and a phase compensation filter
116
perform predetermined processes on this angular velocity data. The angular velocity data passes through a variable HPF
117
. Then, an integrator
118
generates shake correction data for the vertical and horizontal directions. Reference numeral
120
designates a correction system controller, which corrects shakes according to outputs of the angular velocity sensor
111
. The microcomputer
919
transmits data for correcting shakes in the vertical direction to the CCD drive circuit
104
, and data for correcting shakes in the horizontal direction to the memory control circuit
107
, respectively. As mentioned before, the CCD drive circuit
104
and the memory control circuit
107
change the position for extracting lines of the standard image size from the CCD
102
, according to the respective data for correcting shakes
Adams Russell
Canon Kabushiki Kaisha
Robin Blecker & Daley
Smith Arthur A.
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