JP2009265126A - Camera-shake correction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that, in an electronic camera-shake correction in a prior art, catch-up of camera-shake caused during one frame can not be performed. <P>SOLUTION: The camera-shake during one frame is optically corrected and an optical system for the correction is made to be a parallel plate, to simply achieve a camera-shake correction advantageous to cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a camera shake correction technique for a video camera.

  Conventionally, optical correction technology and electronic correction technology have been mainly implemented for the purpose of correcting camera shake.

  Optical correction technology decenters a part of the photographic optical system (hereinafter referred to as a shift unit) and moves the image formed on the image sensor so as to cancel out camera shake. It is to correct.

  In the electronic correction technique, a field angle wider than the field angle to be actually recorded is formed on the image sensor, and a range smaller than the entire range of the image sensor is electronically cut out and recorded as a frame. At this time, camera shake is corrected by moving a range to be cut out following the movement of the image due to camera shake.

  Further, as shown in Japanese Patent Laid-Open No. 2006-261783 (Patent Document 1), it has been proposed to use them together.

  In addition to the above-described camera shake correction technique, there is a technique for obtaining a resolution equal to or higher than the number of pixels of the image sensor as shown in Japanese Patent Laid-Open No. 9-93497 (Patent Document 2). In this technique, a transparent parallel plate is placed on the back focus portion of the optical system, and the parallel plate is tilted to move an image formed on the image sensor within a range smaller than one pixel.

JP 2006-261783 JP JP-A-9-93497

  Among the conventional techniques for correcting the camera shake, the electronic correction technique does not require a mechanically operating part and is an advantageous technique in terms of cost. Since it is performed every time shooting is performed, it cannot follow the movement of an image within a shooting period of one frame (hereinafter referred to as one frame period). For this reason, the movement of the image generated within one frame period remains as an image blur in the image corrected by the electronic correction technique. On the other hand, a method of obtaining an image free from camera shake by shortening the exposure time using an electronic shutter or by photographing and combining a plurality of images within one frame period can be considered. Cameras are difficult to implement because of restrictions on exposure conditions and restrictions on the reading speed from the image sensor.

  Of the conventional techniques for correcting camera shake, the optical correction technique is considered to be capable of correcting image blurring that occurs within one frame period in principle. Therefore, it is not easy to manufacture a highly accurate mechanism. In addition, even if the shift unit moves, the aberration is not greatly affected. Therefore, the shift unit has to be corrected for aberrations alone, which is a limitation in optical design.

  In addition to the technique using the shift unit, as a technique for optically moving an image, there is a technique using a transparent parallel plate as shown in Japanese Patent Laid-Open No. 9-93497 (Patent Document 2). In this technique, since the image is moved by a parallel plate having no optical refractive power, the aberration generated by the parallel plate itself is very small, the positioning accuracy is very loose, and only the relative change in the tilt needs to be managed. Further, since the parallel plate can be put in the back focus portion of the optical system, the total length is not increased. From these characteristics, the method using the parallel plate has less restrictions on the optical design, and is more advantageous than the conventional optical correction technique in terms of cost.

  However, the technique using a parallel plate cannot move an image so much and has not been used for the purpose of camera shake correction.

  Accordingly, an object of the present invention is to provide a camera shake correction technique that can correct the movement of an image within one frame period and has few restrictions on optical design.

  In the present invention, for example, the above-described problem is solved by using the configuration described in the claims.

  According to the present invention, it is possible to realize appropriate camera shake correction.

  The movement of camera shake is roughly a mixture of a low-frequency component with a large amplitude and a high-frequency component with a small amplitude.

  In the conventional electronic camera shake correction, even low-frequency camera shake having a large amplitude is removed, and only the fast camera shake component that occurs within one frame period affects the finally recorded image.

  When a parallel plate is used alone for camera shake correction, camera shake with an amplitude of about several pixels can be corrected even with a fast movement, but not as large as electronic camera shake correction.

  Here, removing the high-frequency component with small amplitude using a parallel plate and removing the remaining high-frequency component with low frequency using conventional electronic image stabilization will further reduce the effects of camera shake. Can be completely removed.

Specifically, in addition to the conventional configuration as the configuration of the video camera, camera shake detection means, a transparent parallel plate inserted into the back focus unit of the optical system, and a drive unit that changes the inclination of the parallel plate, An operation for cutting out the recording range from the image sensor and a control unit for controlling the inclination of the parallel plate are added, and the following operation is performed within one frame period to correct camera shake.
(1) At the start of exposure of one frame, the control unit places the parallel plate at the initial tilt position (hereinafter referred to as the initial tilt position) using the drive unit. The position of the image on the image sensor at this time is set as a reference position.
(2) During the exposure of one frame, the control unit detects the camera shake by the camera shake detection means, and tilts the parallel plate so as to cancel the movement of the image due to the camera shake to keep the image at the reference position.
(3) At the end of exposure of one frame, the control unit returns the parallel plate to the initial tilt position in preparation for the start of exposure of the next frame. Further, when the parallel plate is returned to the initial tilt position, the image on the image sensor moves, and the recording range cut out from the image sensor is moved following the movement of the image. As the amount of movement of the recording range, for example, an amount obtained by integrating the amount of camera shake detected by the above-described camera shake detecting means for one frame period can be used.

As described above, if the movement of the image due to camera shake within one frame period is within a range that can be moved by the parallel plate, it is possible to completely correct the shake similarly to the conventional optical camera shake correction.
In addition, if the movement of the image due to camera shake within one frame period exceeds the amount that can be moved by the parallel plate, the excess amount becomes blurring and blurring of the image, but the amount that can be corrected by the parallel plate. An image with a core can be obtained from the image.
The above effect can be obtained with a mechanism having a lower accuracy than the conventional optical camera shake correction technology, and the cost can be reduced.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram showing a configuration of a camera shake correction apparatus according to the present invention.
In FIG. 1, 1 is an optical system, 2 is an image sensor, 3 is a control unit, 4 is a recording unit, 5 is a camera shake detection unit, 6 is a drive unit, and 7 is parallel. A flat plate and 71 is a hinge. The optical system 1, the image sensor 2, the control unit 3, the recording unit 4, and the camera shake detection unit 5 are basically the same as those used in a conventional electronic camera shake correction device, and are parallel to the drive unit 6. The flat plate 7 and the hinge 71 are elements added for carrying out the present invention. Further, the present embodiment is an example in which only camera shake in either the vertical direction or the horizontal direction is corrected.

  Next, the operation of this embodiment will be described with reference to FIG.

  The optical system 1 forms an image of a subject on an image sensor 2, and the image sensor 2 converts the image into an electrical signal and stores it. The control unit 3 cuts out and reads out the range used for recording from the signal stored in the image sensor 2 and sends it to the recording unit 4. The recording unit 4 records the signal sent from the control unit 3 on a recording medium (not shown). The camera shake detection unit 5 detects camera shake and sends it to the control unit 3 as camera shake information. The control unit 3 uses the camera shake information sent from the camera shake detection unit 5 to detect the camera shake on the image sensor 2. The movement of the image is obtained, and the range to be cut out when reading the signal from the image sensor 2 is instructed to the image sensor 2.

  The above operation is performed every frame period.

  The operation described above for controlling the readout range from the image sensor is the same as that of a conventional electronic image stabilization device. In the present invention, in addition to this, an operation for controlling the inclination of the parallel plate is performed during one frame period as follows.

  The parallel plate 7 is optically transparent, is disposed between the optical system 1 and the image sensor 2, and has one end rotatably fixed by a hinge 71. The drive unit 6 adjusts the inclination of the parallel plate 7 in accordance with instructions from the control unit 3.

  Prior to the start of exposure for one frame period, the control unit 3 uses the driving unit 6 to set the inclination of the parallel plate 7 to the initial inclination position. This initial tilt position is preferably at the center of the rotatable range of the parallel plate 7.

  During the exposure for one frame period, the control unit 3 obtains the amount of movement of the image on the image sensor 2 based on the camera shake information sent from the camera shake detection unit 5, and then parallel plates necessary for canceling the image movement. 7 is calculated and the drive unit 6 is instructed to adjust the inclination of the parallel plate 7.

  After the exposure for one frame period, the control unit 3 uses the drive unit 6 to return the inclination of the parallel plate 7 to the initial inclination position. In addition, as in the case of the conventional electronic camera shake correction device, the control unit 3 integrates camera shake information during one frame period and obtains a cutout position when reading the next frame from the image sensor. 2 is instructed.

  In addition to electronic camera shake correction for each frame, the present invention corrects further camera shake by operating as described above during one frame period.

The angle of the parallel plate performed during the exposure is calculated as follows.
Since the relationship between the inclination angle of the parallel plate and the position of the image is expressed by the following expression, the variable d in the following expression is the same size as the movement of the image obtained from the camera shake information, and the sign is opposite. Find the variable ω in the following equation.

d = (1-1 / N) × t × ω
Here, the meaning of each variable in the above equation is as follows.

ω: Parallel plate tilt angle (angle difference from initial tilt position, in radians)
d: Amount of image movement (based on the position of the image when the parallel plate is at the initial tilt position)
t: Thickness of parallel plate N: Refractive index of parallel plate As an example, the relationship between the angle of the parallel plate and the amount of image movement when an acrylic (refractive index 1.492) plate 2 mm thick is used is shown in the following table. Shown in

  Here, * 1 pixel pitch is 2.09 μm.

  As described above, an acrylic plate having a thickness of 2 mm is used as the parallel plate, and the parallel plate is tilted within a range of ± 2 degrees, thereby canceling the movement of the image within the range of ± 11 pixels.

  A second embodiment according to the present invention will be described with reference to FIGS. This embodiment uses two sets of parallel plates, a parallel plate that corrects camera shake in the vertical direction and another parallel plate that corrects camera shake in the left and right direction. It is characterized by correcting both camera shakes.

FIG. 2 is a block diagram showing the configuration of the camera shake correction apparatus according to the present invention.
In FIG. 2, 1 is an optical system, 2 is an image sensor, 3 is a control unit, 4 is a recording unit, 5 is a camera shake detection unit, and 7p is for camera shake correction in the vertical direction. 71p is a hinge that supports the parallel plate 7p, 6p is a vertical adjustment drive unit that adjusts the angle of the parallel plate 7p, and 7y is a parallel plate for camera shake correction in the horizontal direction, 71y is a hinge that supports the parallel plate 7y, and 6y is a left-right angle adjusting drive unit that adjusts the angle of the parallel plate 7y.

  FIG. 3 is a perspective view showing the arrangement of parallel flat plates of the present embodiment.

  In FIG. 3, 1 is an optical system, 2 is an image sensor, 7p is a parallel plate for correcting camera shake in the vertical direction, 71p is a hinge that supports the parallel plate 7p, and 6p is an angle of the parallel plate 7p. 7y is a parallel plate for correcting camera shake in the left-right direction, 71y is a hinge for supporting the parallel plate 7y, and 6y is a left-right angle for adjusting the angle of the parallel plate 7y. It is an adjustment drive unit.

Next, the operation of this embodiment will be described with reference to FIG.
In this embodiment, the operation for controlling the reading range from the image sensor is the same as that in the first embodiment, and the description thereof is omitted.
The operation of controlling the inclination of the parallel plate during one frame period in this embodiment will be described as follows.

The parallel plate 7 p is optically transparent and is disposed between the optical system 1 and the image sensor 2. The parallel plate 7p is fixed to be rotatable about a horizontal axis by a hinge 71p, and the parallel plate 7y is fixed to be rotatable about a vertical axis by a hinge 71y.
The vertical angle adjustment drive unit 6p adjusts the inclination of the parallel plate 7p around the horizontal axis according to the instruction from the control unit 3, and the left / right angle adjustment drive unit 6y follows the instruction from the control unit 3 to Adjust the tilt around the axis.

  Before the start of exposure for one frame period, the control unit 3 uses the vertical angle adjustment driving unit 6p to set the inclination of the parallel plate 7p to the initial inclination position, and the control unit 3 uses the driving unit 6y to incline the parallel plate 7y. To the initial tilt position. It is desirable that the initial tilt position be at the center of the rotatable range of the parallel plate 7p and the parallel plate 7y.

During the exposure for one frame period, the control unit 3 obtains the vertical movement amount of the image on the image sensor 2 based on the camera shake information sent from the camera shake detection unit 5, and then cancels the vertical movement of the image. Therefore, the angle of the parallel flat plate 7p necessary for the calculation is calculated, and the inclination of the parallel flat plate 7p is adjusted by instructing the vertical angle adjusting drive unit 6p. Further, the control unit 3 obtains the amount of movement of the image on the image sensor 2 in the left-right direction, calculates the angle of the parallel plate 7y necessary to cancel the movement of the image in the left-right direction, and drives for adjusting the left-right angle. The unit 6y is instructed to adjust the inclination of the parallel plate 7y.
After the exposure for one frame period, the control unit 3 returns the inclination of the parallel plate 7p to the initial inclination position by using the vertical angle adjustment driving unit 6p, and the inclination of the parallel plate 7y by using the left / right angle adjustment driving unit 6y. Return to the initial tilt position.

  In addition, as in the case of the conventional electronic camera shake correction device, the control unit 3 integrates camera shake information during one frame period and obtains a cutout position when reading the next frame from the image sensor. 2 is instructed.

  In the present embodiment, the above-described operation is performed to correct camera shake in the vertical direction and the horizontal direction.

  A third embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that camera shake in the vertical direction and the horizontal direction is corrected by a single parallel plate.

  FIG. 4 is a perspective view showing the structure for holding the parallel plates of the present embodiment.

In FIG. 4, 1 is an optical system, 2 is an image sensor, 7 is a parallel plate, 70 is a holder for holding the parallel plate, and 6p is a vertical angle adjustment for adjusting the vertical angle of the holder 70. 6y is a left / right angle adjustment drive unit that adjusts the angle of the holder 70 in the left / right direction, and 8y is fixed to the housing and includes a vertical angle adjustment drive unit 6p and a left / right angle adjustment drive unit 6y. A front holding plate to be held, 81 is a pivot that supports the holder 70 with a point, 9 is a rear holding plate that is fixed to the housing and holds the image pickup device 2, and 10 is on the rear holding plate 9. The elastic member has a role of pressing the holder 70 against the front holding plate 8.
In FIG. 4, the image pickup device 2 is hidden by the holder 7, but its position is shown by a dotted line.

  Next, the operation of this embodiment will be described with reference to FIG.

  In FIG. 4, the front holding plate 8 and the rear holding plate 9 are fixed to the video camera casing, and the distance between them is fixed. The holder 70 that holds the parallel plate 7 is located between the front holding plate 8 and the rear holding plate 9, and is pressed against the front holding plate 8 by the elastic member 10 on the rear holding plate 9. The elastic member 10 can be realized by a spring, for example.

On the front holding plate 8, there are a vertical angle adjusting drive portion 6 p, a left and right angle adjusting drive portion 6 y, and a pivot 81. The pivot 81 supports the holder 70 at one point of the tip, and the front holding plate 8 The distance between the holders 70 is kept constant.
The top and bottom angle adjustment drive unit 6p and the left and right angle adjustment drive unit 6y are in contact with the holder 70, and extend and contract to adjust the distance between the front holding plate 8 and the holder 70 for camera shake correction. At this time, since the length of the pivot 81 does not change, the holder 70 can be tilted in the vertical direction and the horizontal direction with the tip of the pivot 81 as the center.
The up / down angle adjustment drive unit 6p and the left / right angle adjustment drive unit 6y can be realized by, for example, voice coils.

In this embodiment, the operations from the detection of camera shake to the sending of an angle adjustment instruction to the vertical angle adjustment drive unit 6p and the left / right angle adjustment drive unit 6y are the same as those in the second embodiment, and the description thereof will be omitted.
The vertical angle adjustment drive unit 6p and the left / right angle adjustment drive unit 6y that have received the angle adjustment instruction adjust the angles of the holder 70 and the parallel plate 7 by changing their lengths.

  In this embodiment, the camera shake is corrected by operating as described above.

  In this embodiment, since only one parallel plate is inserted between the optical system and the image sensor, it can be easily applied to an optical system having a short back focus.

  The present invention is applicable to all video cameras that require camera shake correction.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

The block diagram which shows the structure of the camera-shake correction apparatus by this invention The block diagram which shows the structure of the camera-shake correction apparatus of 2nd Example by this invention. The perspective view which showed arrangement | positioning of the parallel plate of 2nd Example by this invention. The perspective view which showed the structure holding the parallel plate of 3rd Example by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical system 2 Image pick-up element 3 Control part 4 Recording part 5 Camera shake detection part 6 Drive part 6p Vertical angle adjustment drive part 6y Left / right angle adjustment drive part 7 Parallel plate 7p Parallel plate 7y Parallel plate 70 Holder 71 Hinge 71p Hinge 71y Hinge 8 Front holding plate 81 Pivot 9 Rear holding plate 10 Elastic member

Claims (5)

It is a camera shake correction device used for video cameras,
An image sensor for capturing video information;
An optical axis displacing means arranged in front of the image sensor to displace the optical axis incident on the image sensor;
Camera shake detection means;
Control means for controlling the amount of optical axis displacement by the optical axis displacement means based on the amount of camera shake detected by the hand shake detection means;
The optical axis displacement means uses a parallel plate whose inclination can be controlled by the control means. The camera shake correction device according to claim 1,
The control means cuts out part of the image photographed by the image sensor, performs electronic camera shake correction as a frame to be recorded by a video camera,
The control means changes the position to be cut out from the image taken for each frame of photographing,
The camera shake correction apparatus characterized in that the control means returns the parallel plate of the optical axis displacing means to a reference tilt position every time one frame is shot. The camera shake correction device according to claim 1 or 2,
The optical axis displacement means is composed of two parallel flat plates,
A camera shake correction apparatus characterized in that a direction in which the first parallel plate displaces the optical axis and a direction in which the second parallel plate displaces the optical axis are arranged substantially at right angles in a screen to be photographed. The camera shake correction device according to claim 1 or 2,
The camera shake correction apparatus according to claim 1, wherein the parallel plate of the optical axis displacing means can be tilted in either the vertical direction or the horizontal direction. The camera shake correction device according to claim 4,
The camera shake correction apparatus, wherein the optical axis displacing means includes a voice coil that adjusts a vertical angle of a parallel plate and a voice coil that adjusts a horizontal angle.

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