JP2641611B2 - Image stabilization device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake correction apparatus, and more particularly, to driving at least a part of an optical member of a photographing optical system of a camera and entering an imaging surface via the photographing optical system. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake correction device for stabilizing the light of a subject.

[Prior art] Conventionally, as a camera shake correction device, a correction mirror having an angle of approximately 45 ° with respect to the optical axis of a photographing lens is disposed to be tiltable, and the correction mirror is driven by driving the correction mirror. A device that stabilizes the subject light incident on the imaging surface via the photographing lens, or the entire photographing lens or a part of the lens constituting the photographing lens is tiltably supported by a gimbal mechanism or the like, and the supported lens is driven. And stabilizes the subject light incident on the captured image.

As an angular velocity sensor for detecting the shake of a camera used in this type of mechanical shake correction apparatus, a sensor utilizing Coriolis force is generally used.

[Problems to be solved by the invention]

Incidentally, the angular velocity sensor outputs a voltage signal proportional to the angular velocity. However, it is difficult to detect a small angular velocity (for example, 1 ° / sec) because the Coriolis force itself is small. Therefore, the mechanical image stabilizing device using such an angular velocity sensor has a high effect of correcting a large angular velocity shake, but cannot perform a satisfactory correction for a small angular velocity shake (slow movement).

The present invention has been made in view of such circumstances, and can detect a small angular velocity that a general angular velocity sensor used in a mechanical image stabilization device is not good at, and can completely stop even a slow movement. It is an object of the present invention to provide a camera shake correction device capable of obtaining a corrected image.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a first angular velocity sensor that detects an angular velocity by adding an angular velocity accompanying a camera shake, and a subsequent angular velocity sensor for a preceding image based on image data between fields. Second angular velocity detecting means for detecting an amount of parallel movement of an image per unit time and detecting an angular velocity of the camera based on the amount of parallel movement, and at least a part of an optical member of a photographing optical system of the camera to be movable. And mechanical vibration correcting means for driving the optical member based on outputs from the first and second angular velocity detecting means.

[Action]

According to the present invention, the first and second two types of angular velocity detecting means are used as the angular velocity detecting means used in the mechanical camera shake correction means. That is, the first angular velocity detecting means detects the angular velocity by adding the angular velocity accompanying the camera shake, and the second angular velocity detecting means detects the subsequent angular velocity with respect to the preceding image based on the image data between the fields. The amount of parallel movement of the image per unit time is detected, and the angular velocity of the camera is detected based on the amount of parallel movement. The mechanical image stabilizing means uses two detection outputs of the first and second angular velocity detecting means. Therefore, the first and second angular velocity detecting means can use the two according to their respective angular velocity ranges.

[Embodiment] A preferred embodiment of a camera shake correction apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a video camera provided with a camera shake correction apparatus according to the present invention, and includes a correction mirror.
A mechanical image stabilizer 51 having 10 is provided.

As shown in FIG. 1, subject light is incident on a solid-state image sensor (CCD) 22 via a correction mirror 10 and a photographing lens 20, and is converted into a signal charge of an amount corresponding to the light intensity by each sensor of the CCD 22. Is converted. The signal charges are sequentially read out and output to the A / D converter via the sample and hold circuit 30 and the automatic gain control circuit 32.

The A / D converter 34 converts the input analog signal into a digital signal (image data), outputs this to the signal processing circuit 42, and outputs it to the memory 37 and the motion detection circuit 39.

After performing signal processing such as white balance correction of the input image data, the signal processing circuit 42 outputs this to the recording device 48 via the D / A converter 46. The recording device 48 includes a recording signal processing circuit, converts a video signal input from the D / A converter 46 into a recording signal suitable for magnetic recording, outputs this to a magnetic head, and magnetically records it on a video tape.

The memory 37 stores image data of a predetermined motion detection area in one field, delays the image data by one field period, and outputs it to the motion detection circuit 39.

The motion detection circuit 39 compares the image data in the motion detection area of the current field with the image data in the motion detection area of the previous field added via the memory 37, and determines the direction and amount of motion between the fields ( Differential motion vector). The differential motion vector is obtained by performing a correlation operation on each image data in the motion detection areas of the preceding and succeeding fields, and from the shift amount (parallel movement amount of the screen) at which the correlation value becomes maximum.

Then, the difference motion vector between each field obtained in this way, that is, per unit time (one field period)
Is output to the arithmetic circuit 50.

The arithmetic circuit 50 receives the above-described vector information, and also receives, from the zoom encoder 24, zoom information indicating the moving position (zoom position) of the zoom unit 20A of the photographing lens 20,
The angular velocity of the video camera in the pan direction (X direction) and the tilt direction (Y direction) is calculated based on the vector information, the zoom information, and the sampling period, and a signal indicating the angular velocity is transmitted to the mirror control circuit of the mechanical image stabilizer 51. Output to 52.

Next, the mechanical image stabilizer 51 of the video camera will be described. The mechanical image stabilizer 51 mainly includes a correction mirror 10, a bimorph driver 11, a mirror control circuit 52,
It comprises a mirror drive circuit 54 and an angular velocity sensor 55.

Here, first, a driving mechanism of the correction mirror 10 will be briefly described.

In FIG. 2, the correction mirror 10 is adhered to a mirror base plate 12, and the mirror base plate 12 is made up of four leaf springs 14 (1 in FIG. 2).
(Only one sheet is shown), and is pressed against the chassis 15 with the ball 13 interposed therebetween, and is maintained at a neutral position parallel to the chassis 15 by the urging force of the leaf spring 14. As a result, the mirror base plate 12, that is, the correction mirror 10 is
Are supported so as to be tiltable in all directions.

One end of the bimorph driver 11 is fixed to the chassis 15,
A drive member 16 having a drive pin 16A is attached to the other end. A coil spring 17 is provided between the driving member 16 and the mirror base plate 32.
Is arranged, and the tip of the drive pin 16A is always in contact with the abutment 18 planted on the mirror base plate 12.

According to the mirror driving mechanism having the above configuration, when the tip of the driven bimorph driver 11 is displaced, the driving member 16 is displaced.
Is moved in the direction indicated by the arrow in FIG. 2, whereby the gap between the chassis 15 and the correction mirror 10 is changed. That is, the correction mirror 10 is tilted with respect to the center of the ball 13.

Next, a control system of the bimorph driver 11 will be described.

The mirror control circuit 52 receives signals from the angular velocity sensor 55 and the arithmetic circuit 50 described above.

The angular velocity sensor 55 is, for example, a tuning fork type angular velocity sensor,
The torsion of the tuning fork due to the Coriolis force according to the angular velocity is detected, and a voltage signal proportional to the torsion (angular velocity) is output to the mirror control circuit 52, which is detected by the angular velocity sensor 55 as shown in FIG. Impossible low angular velocity range (± ω
a) For example, a dead zone is provided within ± 1 ° / sec.

On the other hand, the arithmetic circuit 50 outputs a signal indicating the angular velocity only when the calculated angular velocity is within the low angular velocity range (± ωa) as shown in FIG. 3 (B).

The mirror control circuit 52 includes the angular velocity sensor 55 and the arithmetic circuit.
Calculate two signals added from 50 (for example, simply 2
The two signals are added or the two signals are each multiplied by a certain ratio and added), and this is input as an angular velocity signal in a constant cycle. Then, a pulse rate proportional to the magnitude of the angular velocity signal (angular velocity) is determined, and a pulse signal of the determined pulse rate is output to the mirror drive circuit 54 until the next angular velocity signal is input. Thus, a pulse having a pulse rate proportional to the angular velocity is applied to the mirror drive circuit 54.

The mirror drive circuit 54 amplifies the input pulse signal and injects charges into the bimorph driver 11. That is, the mirror driving circuit 54 injects pulse charges of a fixed size at intervals corresponding to the pulse rate of the input pulse signal.

As a result, a charge amount proportional to the angular velocity is injected into the bimorph driver 11, and the bimorph driver 11 is displaced in proportion to the charge injection amount to tilt the correction mirror 10. When the sign of the input angular velocity signal is inverted, the polarity of the pulse signal output from the mirror control circuit 52 is also inverted, and the bimorph driver 11 is displaced in the opposite direction.

Since the above operation is repeatedly performed in a short cycle, the correction mirror 10 tilts at an angular velocity proportional to the angular velocity of the video camera, thereby stabilizing the subject light incident on the photographing lens 20. However, the gain and the like of the mirror drive circuit 54 are adjusted in advance so that the correction mirror 10 is tilted in the opposite direction at half the calculated angular velocity.

In this embodiment, for simplicity, the mechanical image stabilizer 51 is described for only one system in the X direction or the Y direction.
It has two independent control systems that perform camera shake correction in the direction and the Y direction. Further, the mechanical image stabilizer is not limited to the one using the correction mirror of the present embodiment, and the control method thereof is not limited to the present embodiment, and various methods can be considered.

〔The invention's effect〕

As described above, according to the camera shake correction apparatus of the present invention, the parallel movement amount per unit time of the succeeding image with respect to the preceding image is detected from the image data, and the low angular velocity range of the camera is determined based on the parallel movement amount. The angular velocity range that cannot be detected by the angular velocity sensor used in the mechanical image stabilization device can also be accurately detected because the angular velocity is detected, thereby completely stopping even a slow movement. Camera shake correction can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a video camera provided with a camera shake correction apparatus according to the present invention. FIG. 2 is a cross-sectional view showing details of a mirror driving mechanism of a mechanical camera shake correction unit in FIG. 3 (A) and (B) are graphs each showing an example of the output of the angular velocity sensor and the arithmetic circuit shown in FIG. 1. 10: correction mirror, 11: bimorph driver, 20: photographing lens, 20A: variable magnification unit, 22: solid-state image sensor (CCD), 24: zoom encoder, 39: motion detection circuit, 37 …… Memory, 50 …… Calculation circuit, 51 …… Mechanical image stabilization section, 52 …… Mirror control circuit, 54 …… Mirror drive circuit, 55 …… Angular velocity sensor.

Claims (3)

(57) [Claims] 1. A first angular velocity sensor for detecting an angular velocity by adding an angular velocity caused by camera shake, and a parallelism per unit time of a succeeding image with respect to a preceding image based on image data between fields. A second angular velocity detecting means for detecting an amount of movement and detecting an angular velocity of the camera based on the amount of parallel movement; and at least a part of an optical member of a camera optical system is movably disposed; And a mechanical image stabilizing means for driving the image stabilizing means based on outputs from the first and second angular velocity detecting means. 2. The apparatus according to claim 1, wherein the second angular velocity detecting means detects a focal length of the photographing lens, and calculates an angular velocity of the camera based on the parallel movement amount per unit time and the detected focal length. 2. The image stabilizing apparatus according to claim 1, further comprising: 3. The image stabilizing device according to claim 1, wherein the optical member is driven based on an output of the first angular velocity detecting means when the detected angular velocity is equal to or higher than a predetermined angular velocity. 3. The camera shake correction device according to claim 1, wherein the optical member is driven based on an output of the detection unit.