Field of the Invention
The present invention is generally directed to an apparatus and a method for correction based upon detecting a deviation from a proper position of a camera, and more particularly is directed to an apparatus for correcting deviation from the proper camera position caused by shaking, such as hand shaking.
Digital video cameras and digital still cameras as kinds of cameras are well known. When those kinds of cameras shoot a subject, the optical system of such cameras bring rays of light corresponding to the subject to a focus at an image pickup device and change the light information into electric signals.
When camera shaking occurs in a digital video camera by, e.g., hands of the camera operator shaking, pictures taken by the camera slightly oscillate from the camera shaking. As a result, it is hard to watch the reproduced pictures of the digital video camera.
A digital still camera can not realize short exposure time because the sensitivity of the image pickup device is limited. As a result, the digital still camera goes out of focus when the camera shaking occurs. That results in the pictures taken by the digital still camera becoming blurry.
Certain cameras have a function of correcting deviation caused by a slight oscillation based on a hand of an operator holding the camera shaking or by another cause for making the camera shake.
Some methods have been proposed to detect a camera shaking, and such methods utilize devices such as angular velocity sensors, a piezoelectric gyro sensor, an acceleration sensor, and an optical detecting sensor. Another known method corrects a camera shaking by utilizing an image processing method. The most popular method for addressing camera shaking utilizes a piezoelectric gyro sensor for detecting a rotary motion of the camera body.
Furthermore, detecting methods which utilize combinations of the above devices have also been suggested.
When a camera employs a piezoelectric gyro sensor, the piezoelectric gyro sensor detects angular velocity around each axis X, Y, Z of the camera. After the detection of the angular velocity, an optical system of the camera is adjusted along each axis, a vari-angle control mechanism adjusts a variable rotation angle (vari-angle) prism, a reflection mirror in the optical system is adjusted, and an image sensing device is moved appropriately by a motor, etc. Utilizing a piezoelectric gyro sensor as an angular velocity sensor which detects the angular velocities along each of the plural axes has been commercialized in a camera.
A method for detecting angular velocity by pairs of acceleration sensors is disclosed in Japanese Laid Open Patent Application 8-101,418 and Japanese Laid Open Patent Application 05-173,219. In the methods disclosed in those documents, the angular acceleration is detected by differential amplifying an output of plural acceleration sensors.
However, the present inventor has realized that camera shaking is ascribable to rotations based on an up-and-down motion and a side-to-side motion relative to the direction of the optical axis, and based upon rotation around the optical axis. Data corresponding in all directions of the X, Y, Z axes is thereby necessary when a system carries out proper correction for camera shaking.
In Japanese Laid Open Patent Application 07-225,405, the correction of camera shaking based upon angular velocities corresponding to all axes X, Y, Z is disclosed. That document, however, does not disclose the details of the method of the correction of the camera shaking based upon the three angular velocities.
Therefore, the above-noted background art systems can not correct for camera shaking based upon rotations based on an up-and-down motion and a side-to-side motion relative to the direction of the optical axis, and based upon rotation around the optical axis.
Accordingly, one object of the present invention is to provide a novel system for correcting for any adverse influences generated by a camera shaking.
A more specific object of the present invention is to provide a novel system which overcomes the drawbacks in the background art as noted above.
To solve the above-noted and other problems, according to one aspect of the present invention, an apparatus for detecting a deviation of a camera from shaking includes a shaking detector which detects a shaking of the camera based upon an output from angular velocity sensors located on camera coordinate axes, a calculator which calculates rotation angles of each of the axes based on the output of the angular velocity sensors, and a rotation regulator which rotates an image pickup device around an axis in parallel with the optical axis based on the calculated rotation angles.
A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
a) is a spectrum of detected angular velocity by an angular velocity sensor X in the present invention;
b) is a spectrum of detected angular velocity by an angular velocity sensor Y in the present invention;
c) is a spectrum of detected angular velocity by an angular velocity sensor Z in the present invention;
a) is a perspective view of a camera according to a second embodiment of the present invention;
b) shows a location between pairs of bimorph actuators and a CCD device in the present invention;
a) is a perspective view of a camera according to a third embodiment of the present invention;
b) is a cross-sectional view of an actuator for a CCD in the third embodiment of the present invention;
a) is a spectrum of detected acceleration by acceleration sensors in the present invention;
b) is a spectrum of frequency when a camera shaking occurs;
a) shows a location between a multi-layer piezoelectric actuator, a rotating shaft, and a CCD device in the present invention;
b) shows a location between a motor, a rotating shaft, and a CCD device in the present invention;
a) is a cross-sectional view of an optical system in which a vari-angle prism is employed when camera shaking does not occur in the present invention;
b) is a cross-sectional view of an optical system in which a vari-angle prism is employed when camera shaking occurs in the present invention;
A description will now be given of preferred embodiments according to the present invention by referring now to the drawings, wherein like reference numerals designate identical or corresponding structures throughout the views.
The camera 1 includes a camera body 10 and a lens 11. An angular velocity sensor X, an angular velocity sensor Y, an angular velocity sensor Z, such as piezoelectric gyro sensors, and an image pickup device 12 are set up in the camera body 10. A board (not shown) equipped with a controller and actuators is also set up in the camera body 10. The board equipped with the controller and the actuators is described later. In this embodiment, the image pickup device 12 employs a 2-dimensional CCD.
The angular velocity sensor Z is located on the optical axis. The camera coordinate system is defined such that the direction of the optical axis is the Zs axis, the gravity direction is the Ys axis, and the horizontal direction perpendicular to both the Zs axis and the Ys axis is the Xs axis. The angular velocity sensors X, Y are respectively located on the Xs axis and the Ys axis. In the above camera coordinate system, the point of origin is at a center of the imaging surface of the CCD 12.
When an operator holds the camera 1 at a general position, the YZ plane becomes a vertical plane against a horizontal plane, and the Xs axis becomes a horizontal direction. The angular velocity sensor X is capable of detecting an up-and-down motion based on the camera shaking, which is referred to as shaking in a pitching direction as shown in the direction of an arrow A in
Similarly, the angular velocity sensor Y is capable of detecting a side-to-side motion based on the camera shaking, which is referred to as shaking in a yawing direction as shown in the direction of an arrow B in
Therefore, the angular speed sensors X and Y are capable of detecting the camera shaking corresponding to yawing and pitching based on the camera shaking. Furthermore, the angular velocity sensor Z is capable of detecting rotation around the Zs axis of the camera.
According to
Now referring to
Each angular velocity sensor detects the rotation around an axis in parallel with the Xs, Ys, Zs axes. The signals of each angular velocity sensors X, Y, Z are shown in
Referring to
A pair of acceleration sensors X1, X2, a pair of acceleration sensors Y1, Y2, and a pair of acceleration sensors Z1, Z2 are located, respectively, on the Xs, Ys, and Zs axes. The camera 1 includes a camera body 10 and a lens 11. The pair of acceleration sensors X1, X2, the pair of acceleration sensors Y1, Y2, the pair of acceleration sensors Z1, Z2, an image pickup device 12 such as a CCD, a board 15 equipped with a controller 16, and actuators 17, 18 are set up in the camera body 10. The CCD 12 is supported on a support board 19 located on the board 15 via bimorph actuators 17 and 18. The camera 1 brings into focus a target object which is located at an object position (Ob). The image corresponding to the target object is focused at an imaging surface of the CCD 12 by lens 11.
The pair of acceleration sensors Z1, Z2 is located on the optical axis. The camera coordinate system is defined such that the direction of the optical axis is the Zs axis, the gravity direction is the Ys axis, and the horizontal direction perpendicular to both the Zs axis and the Ys axis is the Xs axis. In the above camera coordinate system, the point of origin is at a center of the imaging surface of the CCD 12.
When an operator holds the camera 1 at a general position, the YZ plane becomes a vertical plane against a horizontal plane, and the Xs axis becomes a horizontal direction. The pair of acceleration sensors Z1, Z2 is capable of detecting an up-and-down motion based on the camera shaking, which is referred to as shaking in a pitching direction as shown in the direction of an arrow A in
Therefore, the two pairs of acceleration sensors Z1, Z2 and X1, X2 are capable of detecting the camera shaking corresponding to yawing and pitching which are susceptible to taking an image. Furthermore, the pair of acceleration sensors Y1, Y2 is capable of detecting rotation around the Zs axis of the camera shaking. The pair of the acceleration sensors Y1, Y2 is also located apart from each other at a predetermined distance in the Ys direction.
According to
Now referring to
Now referring to
When the camera body 10 is inclined at an angle θ toward Ob in the YZ plane as a result of an up-and-down motion of the camera, the output of the acceleration sensor Z1 is acceleration A1 at a distance L1′ from Ob, and the output of the acceleration sensor Z2 is acceleration A2 at a distance L2′ from Ob. The accelerations A1 and A2 are described in the following equations (1) and (2). In the equations (1), (2), ω is rotation angular velocity, and t is time.
When equation (1) is subtracted from equation (2):
The distance (L2′−L1′) equals the distance between the position of acceleration sensor Z1 and the position of the acceleration sensor Z2 (L2−L1). The distance (L2−L1) is a predetermined unique value for each camera. Further, the subtraction of the accelerations (A2−A1) can be calculated based upon the output of the pair of the acceleration sensors Z1, Z2. Therefore, the angular acceleration (dω/dt) can be obtained from the above equations (1), (2), (3).
Proceeding to a next step, before the exposure by the camera is carried out, a position of the camera 1 is defined as an initial position and an initial time is defined as t=0 at the initial position. During exposure, the angular acceleration (dω/dt) is integrated with respect to t between every time interval, which are divided plural time sectors from t=O to the total exposure time period. The angular velocity θ and the rotation angle θ are then calculated.
A camera shaking by rotation around an axis in parallel with the Ys axis based on the side-to-side motion of the camera is similarly calculated based upon the output of the pair of acceleration sensors X1, X2.
Now referring to
Now referring to
Now referring to
The focus distance of the lens 11 is f. The distance L′ is a distance between the focus point of the lens 11 and the image focusing point in the CCD 12. The distance L is a distance between the focus point of the lens 11 and the point of the object. A detail of the explanation of the distances L, L′ is described in “Point To Note and How to Use of Optical Device in Order to Use the Optelectronics Technique”, by Tetsuo Sueda, Optelectronics, P36–37, the contents of this reference being hereby incorporated herein by reference. A scaling β is defined as β=f/L, and L′=f2/L, leading to equation (4) below.
ΔY=(1+β)2·θx·f (4)
The following equation (5) is derived from the above equation (4) differentiated with respect to time t.
Similarly, the equation (6) is also derived from an equation differentiated with respect to time t when a rotation θy around an axis in parallel with the Ys axis occurs as a result of the camera shaking, and a focus point of the object moves out from the initial point O to point C.
The vales dθx/dt and dθy/dt can be derived from the integrated value of the dto/dt in the equations (1) and (2). Therefore, the values ΔX and ΔY are derived from the above equations. The values ΔX and ΔY are values that the distance of the image focusing point in the CCD 12 should be corrected by the adjustment of the position of the CCD 12, or the optical system.
Now referring to
The low pass filter of filters 31, 32 cuts the component of the frequency more than 20 Hz in the output of the acceleration sensors. A similar structure is employed for filters 33, 34 which receive outputs from the accelerator sensors X1, X2.
Referring to
Still referring to
Finally, the CCD 12 is adjusted to the proper positioning based on the driving of the actuators.
Now referring to
The correction lens 122 is a lens for adjustment of the camera shaking and is capable of moving within the XY plane that is perpendicular to the optical axis. An actuator 53 moves the correction lens 122 in the Xs axis. An actuator 54 moves the correction lens 122 in the Ys axis. The position detectors 51 and 52 can detect the position of the correction lens 122 after adjustment.
The actuators 53, 54 and position detectors 51, 52 are a part of a mechanical portion for the correction of the camera shaking. The MPU 60 is a part of a controller which drives the actuators 53, 54, 56 according to the acceleration detected by the pairs of acceleration sensors Y1, Y2 and X1, X2 in element 240 and position information of each position detector 51, 52, 55.
A trigger device 61, such as a shutter release button, generates a trigger signal when the shutter release button is pushed to a halfway position. When the trigger signal is generated, the controller inputs electric power into the acceleration sensors and the drivers of the actuators. The acceleration sensors and the drivers only require the electric power during taking a shot. Therefore, the electric power supply controlled according to the trigger signal avoids electric power loss.
The above embodiment is also capable of employing a magnetostriction device or an ultrasound motor, as other examples.
Now referring to
Referring to
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The other elements in
Now referring to
A vari-angle prism 65 is located in the optical system on the optical axis. The vari-angle prism can control a variable rotation angle as shown in
Still referring to
The other elements in
Referring to
First, in a step S1, when the operator pushes a release button to a halfway position, the shooting is started. The operation then proceeds to a step S2, in which the correction of the camera shaking starts, and the process then proceed to a step S3. At step S3, the detected angular velocities by the angular velocity sensors are compared with a threshold value. When the detected angular velocities are greater than the threshold value, the process proceeds to a step S4. When the detected angular velocities are less than the threshold value, the process proceeds to a step S5, and the shooting is carried out with the correction of the camera shaking.
At the step S4, the system presents a warning to the operator.
Now referring to
When the range of the acceleration exceeds 0.1 m/s2, the camera needs the correction of the camera shaking.
Referring to
First, in a step S11, when the operator pushes a release button to a halfway position, the shooting is started. The operation then proceeds to a step S12, in which the correction of the camera shaking starts, and the process then proceeds to a step S13. At step S13, the detected accelerations by the acceleration sensors are compared with a first threshold value (e.g. 0.05 m/s2). When the detected accelerations are greater than the first threshold value, the process proceeds to a step S14. When the detected accelerations are less than the first threshold value, the process proceeds to a step S17, and the shooting is carried out without the correction of the camera shaking.
At the step S14, the detected accelerations are further compared with a second threshold value (e.g. 0.1 μm/s2). When the detected accelerations are greater than the second threshold value, the process proceeds to a step S15. When the detected acceleration is less than the second threshold value, the process proceeds to a step S18 and the camera parameters, such as shutter speed, zoom power, etc., are changed, and the process then proceeds to a step S19. At the step S19, the shooting is carried out.
At the step S15, the correction of the camera shaking is carried out and the process proceeds to a step S16. At the step S16, the shooting is carried out.
Now referring to
If the detected angular velocity or detected acceleration is more than the second threshold, the highest position of the LCD finder 70 is lighted and a warning is presented to the user by an indication. Therefore, the user can determine the level of the camera shaking by the indicator 71 in the LCD finder 70.
Now referring to
At a step S21, when the operator pushes a release button to a halfway position, the shooting is started. The process then proceeds to a step S22. At step S22, the acceleration sensors or the piezoelectric gyro sensors detect angular velocities in the direction of the Xs, Ys, and Zs axes. The process then concurrently proceeds to steps S23 and S26.
At the step S23, the correction value of the Xs and Ys axes directions are calculated, and then the process proceeds to a step S24. At the step S24, a driving value of the position of the correction lens 122 or adjustment value of the vari-angle prism 65 is calculated, and the process then proceeds to a step S25. The correction of the position of the correction lens 122 or the adjustment of the vari-angle prism 65 is carried out at the step S25. The process then proceeds to a step S29.
On the other hand, at the step S26, the rotation value of the Zs axis is calculated, and then the process proceeds to a step S27. At the step S27, the rotation angle around Zs axis is carried out. The process then proceeds to a step S28. The adjustment of the rotating position of the CCD 12 is carried out at the step S28 and the process then proceeds to a step S29, and finally the shooting is carried out after the correction of the camera shaking.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the present invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts, as well as implementation in software, hardware, or a combination of both within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
The present document is based on Japanese priority document 10-253,657 filed in the Japanese Patent Office on Sep. 8, 1998, the entire contents of which are incorporated herein by reference.
Obviously, numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.
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