JP3460385B2 - Image stabilization device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image stabilizer suitable for use in, for example, a handy type video camera device.

[0002]

2. Description of the Related Art Today, handy type video camera devices provided with a so-called CCD image sensor are in widespread use.

The handy-type video camera device, which is small and lightweight, has a problem that camera shake is likely to occur during image pickup. If camera shake occurs during the above-described image pickup, for example, when a zoomed-up image is played back, a fine “shaking” occurs in the played back image, making it very difficult to see the played back image.

As a method for correcting the "shake" due to the above-mentioned camera shake to make the reproduced image easier to see, there is known a technology for correcting the camera shake by a camera shake correction device provided in a video camera device. In this camera shake correction apparatus, as a correction means for correcting the camera shake, there is known one that adopts a method of correcting by image processing or a method of correcting by optical processing.

A memory control system and a CCD drive control system are known as correction means for correcting camera shake by the above image processing.

In the above memory control system, when camera shake is detected, a part of a video signal obtained by picking up an image of a subject is taken out as an image frame and moved so that the image frame of the previous field and the image frame of the current field are aligned with each other. The two image frames are matched with each other, and the correction range is secured by enlarging the image of the image frame portion. When this image is enlarged, the image signal is enlarged beyond the resolution of the CCD image sensor, so that the quality of the reproduced image is deteriorated. This deterioration in image quality becomes larger as the correction range becomes wider. Therefore, in this method, the image quality is deteriorated and the correction range cannot be widened. However, the correction means adopting this method is suitable for a small and low-priced video camera device because it is composed of only an IC.

In the CCD drive control system, when a camera shake is detected, a video signal obtained by picking up an image of a subject is C
The correction is performed by changing the timing of reading from the CD image sensor. In this method, the correction range is ensured by increasing the number of pixels of the CCD image sensor, so that the shake correction is performed even when “shaking” appears to be magnified like a subject photographed at high magnification. Therefore, it is necessary to increase the number of pixels. However, if the number of pixels is increased so as to sufficiently perform the camera shake correction due to the enlarged “vibration”, the CCD image sensor and the CCD
The peripheral circuits of the image sensor are large and expensive, and are not practical. For this reason, in the correction means actually adopting this method, the number of pixels for sufficiently correcting the camera shake of the enlarged “shake” is not secured, so that the camera shake of the enlarged “shake” is corrected. There is a discontinuous portion in the image of the reproduced image that is being generated due to camera shake. However, the camera shake correction is performed without any problem at a normal photographing magnification, and since it is composed of only an IC, it is suitable for a small and low-priced video camera device.

Gimbal mechanical system and active prism system are known as the correction means for correcting the camera shake by the optical processing.

When the camera shake is detected, the gimbal mechanical system moves the entire lens unit in a direction for canceling the camera shake to correct the camera shake. With this method, the resolution is not deteriorated and the correction range can be made relatively wide, but since the entire lens unit is moved, the mechanism becomes large and the power consumption also becomes large. Therefore, the correction means adopting this method is suitable when high resolution is desired even if the size is somewhat large.

When the camera shake is detected, the active prism system corrects the camera shake by moving only a part of the lens unit in the direction of canceling the camera shake. Therefore, in this method, the power consumption is small, the miniaturization is easy, the resolution is not deteriorated, and the correction range is relatively wide. By preventing camera shake by this active prism system, it is possible to realize a handy type video camera device that is high in image quality, small in size and light in weight, without causing "jitter" in reproduced images.

The active prism used in this active prism system connects two glass plates with a stretchable bellows made of a special film, and has an optical refractive index almost the same as that of the above two glass plates. It is formed by injecting the liquid. This active prism is an objective lens provided on the front surface of the video camera body for guiding the subject image from the subject to the video main body, and the objective lens and the CC of the lens unit for guiding the subject image to the CCD image sensor.
In each of the two glass plates provided at a position between the D image sensor and each of the two glass plates, a tilt angle (hereinafter referred to as an apex angle with respect to a vertical direction or a horizontal direction) of the video camera main body is different. (Referred to)) is varied to correct camera shake. The injected liquid may generate bubbles under a low atmospheric pressure and cannot sufficiently perform camera shake correction, but it can be used without problems under a normal atmospheric pressure.

All of these correction means for correcting camera shake are for correcting camera shake when camera shake is detected. A motion vector detection method and an angular velocity detection method are known as shake amount detection means for detecting this camera shake.

The above-mentioned motion vector detecting method detects the amount of movement and the direction of the object by obtaining the difference between the image signals of the object of the current field and the previous field stored in the semiconductor memory by image processing. is there. This method has a drawback that it is likely to malfunction at low illuminance. However, the camera shake amount detecting means adopting this method is suitable for a small-sized and low-priced video camera device because it is composed of only an IC.

The above-mentioned angular velocity detection method detects an angular velocity by using an angular velocity sensor such as a piezoelectric vibrating gyro. It requires a large space as compared with an IC because it is a mechanical component, but it malfunctions depending on illuminance conditions. Without being detected in real time. For this reason, the camera shake amount detecting means adopting this method is suitable for a video camera device that accurately performs camera shake correction.

The camera shake correction device used in the handy type video camera device is a motion vector detection system,
Alternatively, a shake amount detection unit that detects a shake of an image caused by a shake of the video camera body by an angular velocity detection method, a correction signal generation unit that generates a correction signal based on an output signal of the shake amount detection unit, and a memory control method, A correction means for correcting camera shake based on a correction signal generated by the correction signal generation means by a method based on image processing such as a CCD drive control method or an optical processing method such as a gimbal mechanical method or an active prism method.

By the way, the angle of the video camera device changes not only by hand shake, but also by panning (a method of taking a picture by swinging the camera left and right) / tilting (moving the camera from top to bottom or from bottom to top). It may be due to camera work such as (shooting method).

Generally, there are some slow and quick camera works, and a large speed change between the beginning and the end of the camera work. 5Hz or less and 15Hz
The above frequency components are generated.

Further, the frequency band of this camera work has a width due to individual differences.

The frequency component of the camera shake is 5 to 8 Hz when the photographer photographs on a stationary body without performing camera work. When the photographer photographs on a moving body, for example, in a car, the main frequency component of camera shake shifts to 20 to 25 Hz on the high frequency side. Further, there is a width due to individual differences in the frequency band of this camera shake.

In the above-mentioned camera shake correction apparatus having the above-mentioned structure, generally, 2 to 30H is taken into consideration in consideration of the case where the camera shake occurs when the photographer performs camera work on the moving body.
In the frequency range of z, the camera shake is corrected by performing servo control so as to cancel the shake of the image due to the camera shake without correcting the camera shake due to the camera work. Therefore, the reproduced image of the video camera device is an image that is easy to see without causing “shaking” due to camera shake.

[0021]

By the way, in the above-described camera shake correction device, when the amplitude value of the angle signal exceeding the correction range is detected by the shake amount detection means as shown in FIG. 5, the correction signal generation means, A correction signal is generated with a value that is inversely proportional to the amplitude value of the angle signal, and the correction means is supplied with the correction means to perform servo control such that the apex angle of the correction means is returned to swing, thereby canceling the image shake. Make a correction.

For this reason, in the video camera device provided with the above-mentioned camera shake correction device, when the shaking stops after the shaking occurs beyond the correction range, the video camera device stands still. Instead, swinging back occurs at the apex angle of the correction means.

Therefore, there is a problem in that an unnatural movement occurs in the image in response to the swinging back of the apex angle of the correction means. This unnatural movement of the image becomes particularly noticeable when the video camera device is mounted on a tripod or the like and is being photographed in a fixed state, when the arrangement position of the tripod or the photographing angle is changed.

In view of the above problems, it is an object of the present invention to provide a camera shake correction device that naturally corrects an image even when a shake occurs beyond the correction range of the correction means.

[0025]

SUMMARY OF THE INVENTION A camera shake correction apparatus according to the present invention includes a shake amount detecting means for detecting the shake amount of an image caused by a shake of a video camera body, and an output signal of the shake amount detecting means. On the basis of the correction signal generating means for variably setting the compensation amount for generating the correction signal for correcting the shake of the image based on the correction signal, the shake of the image is corrected according to the correction signal generated by the correction signal generating means. Correcting means, fixed state detecting means for detecting whether or not the video camera body is in a fixed photographing state based on the amount of shake detected by the shaking amount detecting means, and fixed photographing state by the fixed state detecting means. When the shake amount of the predetermined amount or more is detected by the shake amount detecting means after the detection of, the compensation amount setting means for setting the compensation amount of the correction signal so as to reduce the shake return amount of the correcting means. Provided with a door.

Further, the compensation amount setting means is characterized in that the compensation amount of the correction signal is set so as to reduce the swing-back amount of the correction means after the center position of the correction means.

[0027]

In the image stabilization apparatus according to the present invention, when the fixed amount detecting means detects the fixed photographing state and then the shake amount detecting means detects a shake amount of a predetermined amount or more, the compensation amount setting means The compensation amount of the correction signal generation unit is set so as to reduce the swing-back amount of the correction unit.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the image stabilization apparatus according to the present invention will be described below with reference to the drawings. The camera shake correction device according to the present invention is provided, for example, for camera shake correction of a handy type video camera device. The camera shake correction device shown in FIG. 1 is an example of the camera shake correction device when the angular velocity detection method is adopted as the shake amount detection means and the active prism method is adopted as the correction means.

The image stabilization apparatus provided in the handy-type video camera apparatus according to the present invention shown in FIG. 1 includes a shake amount detection means 1 for detecting the shake amount of an image caused by the shake of the video camera body, From the output signal of the shake amount detecting means 1, the correction signal generating means 2 for generating the correction signal based on the output signal of the shake amount detecting means 1, the correcting means 3 for correcting the shake of the image based on this correction signal, and the output signal of the shake amount detecting means 1. A fixed state detecting unit 4 for detecting a photographing state and a compensation amount setting unit 5 for setting a compensation amount of the correction signal according to a detection output of the fixed state detecting unit 4 are provided.

The shaking amount detecting means 1 employs an angular velocity detecting method composed of a piezoelectric vibration gyro or the like,
The video camera body is provided with its detection surfaces facing in the vertical direction and the horizontal direction, and is caused by a roll direction (hereinafter referred to as yaw direction) and a pitch direction (hereinafter referred to as pitching direction), respectively. It has a first angular velocity sensor for detecting an angular velocity and a second angular velocity sensor.

The first angular velocity sensor and the second angular velocity sensor are the active prism 1 of the correction means 3 which will be described later.
The active prism 11 is located near 1 so that the angular velocities of the active prism 11 in the yawing direction and the pitching direction can be detected.

The shaking amount detecting means 1 having the above structure detects each angular velocity due to the shake in the yawing direction and the pitching direction of the video camera body by using the first angular velocity sensor and the second angular velocity sensor. , And outputs this output signal to the correction signal generating means 2.

The correction signal generating means 2 has a high-pass filter 6 for cutting low frequency components of the output signals of the first angular velocity sensor and the second angular velocity sensor sent from the camera shake amount detecting means 1, and the high-pass filter 6. An integration filter 7 that integrates the angular velocity signal output from the high-pass filter 6 into an angle signal
And a characteristic compensation filter 8 in which the gain and phase for compensating the angle signal are variably set, and the pass center frequency of the angle signal is variably set.

The high-pass filter 6 is formed by an active filter such as a third-order active filter, and, for example, the resonance frequency of the measurement system of the output signals of the first angular velocity sensor and the second angular velocity sensor. It is a filter that cuts noise components of low frequency signals in unnecessary bands such as.

The high-pass filter 6 cuts low-frequency noise components and discriminates the angular velocity signal from the output signal. This discriminated angular velocity signal is sent to the integral filter 7.

The integration filter 7 samples the angular velocity signal discriminated by the high pass filter 6 at a sampling frequency sufficiently higher than the pass center frequency of the characteristic compensation filter 8 and performs A / D conversion. 2, a D / D converter, an adder 21 that adds the sampled angular velocity signal and the output signal of the multiplier 23, and a delay circuit 22 that causes a phase delay in the output signal of the adder 21, as shown in FIG. The output signal of the delay circuit 22 is amplified by a compensation value K ₀ which can be set variably and is supplied to the adder 21. The angular velocity signal output from the adder 21 and the angular velocity signal The sum of products with the sampling time of is calculated.

The multiplier 23 detects the value of the output signal of the delay circuit 22 and sets a value inversely proportional to the value of the output signal as the compensation value K ₀ , and the detector 24. Multiplier 25 for multiplying by the compensation value K ₀ set in 24
Have and.

The transfer function θ ₀ of the configuration shown in FIG.
Represents the phase delay of the delay circuit 22 in the operator Z ^-1, is expressed by the following equation (1) using a compensation value K _0, the compensation value K ₀ is the input signal supplied from the delay circuit 22 A value inversely proportional to the amplitude value is set.

[0039]

[Equation 1]

In the integral filter 7, after the fixed mode is detected by the fixed state detecting means 4, the compensation amount setting means 5 is set.
Thus, the compensation value K ₀ is set so that the swing-back amount of the correction unit 3 becomes zero when the swing amount detecting unit 1 detects a swing of a predetermined amount or more.

The integration filter 7 having the above-mentioned configuration integrates the sum of the products of the angular velocity signals sent from the high-pass filter 6 and the sampling time thereof, so that the yawing direction due to the shake of the video camera body is caused. The angle signal of the shake between the pitching direction and the pitching direction is obtained. The angle signal between the yawing direction and the pitching direction is sent to the characteristic compensation filter 8.

The characteristic compensation filter 8 is a band pass filter formed by a digital filter. The transfer function θ ₁ of the characteristic compensation filter 8 is phase-compensated by transmission from the output side of the first and second angular velocity sensors of the shake amount detection means 1 to the output side of the characteristic compensation filter 8 of the correction signal generation means 2. When the values are K ₁ and K ₂ , the operator Z ⁻¹ due to the phase delay is used, and the gain compensation value of the characteristic compensation filter 8 is K ₃ , it is expressed by the following equation (2).

[0043]

[Equation 2]

The characteristic compensating filter 8 has the above-mentioned compensation value K.
It is possible to variably set ₁ , K ₂ , and K ₃ . When the compensation values K ₁ , K ₂ , and K ₃ are changed, the frequency characteristic of the transfer function θ ₁ changes, as is clear from the above equation (2). Therefore, the pass center frequency of the angle signal input to the characteristic compensation filter 8 changes, and the characteristic compensation filter 8
The frequency characteristic of the correction signal output from the device changes.

This characteristic compensation filter 8 makes it possible to change the frequency characteristic of the correction signal.

The correction signal generating means 2 having the above structure is
The output signal from the first and second angular velocity sensors sent from the camera shake amount detection means 1 is used as an angular velocity signal whose noise has been cut by the high-pass filter 6, and this angular velocity signal is used as an angular signal by the integration filter 7. The angle signal is used as a correction signal by the characteristic compensation filter 8. In the correction signal generation means 2, the compensation values K ₁ , K ₂ , and K ₃ of the characteristic compensation filter 8 are variably set via the characteristic setting means 5, and the correction signal generated by the characteristic compensation filter 8 is set. The phase compensation characteristic and the frequency characteristic of gain are variably set.
This correction signal is sent from the correction signal generation means 2 to the correction means 3.

The correcting means 3 employs an active prism system, and includes an active prism 11, a prism vertical angle sensor 12 for detecting a vertical angle signal of the active prism 11, and the active prism 11. And a prism control unit 13 that variably drives the apex angle.

In the active prism 11, two glass plates are connected by a stretchable bellows made of a special film, and a liquid having an optical refractive index almost the same as that of the two glass plates is injected into the active prism 11. It is formed. Each glass plate of the two glass plates is provided so that the apex angle can be variably set in any one of the vertical direction and the horizontal direction of the television camera body, which are different from each other.

The active prism 11 is arranged in the lens unit in front of the image receiving portion of the CCD image sensor for receiving the image of the subject from the subject through the objective lens.

By changing the apex angle of each of the two glass plates of the active prism 11 in the direction for canceling the camera shake, the active prism 1
The shake of the subject image received by the CCD image sensor from the subject through "1"
A subject image that does not cause

The prism apex angle sensor 12 is located on the side surface of each of the two glass plates of the active prism 11, and is erected so as to be parallel to the vertical and horizontal directions of the video camera body. The first and second arms and this first,
It has a first photo sensor and a second photo sensor for detecting the vertical angle between the yawing direction and the pitching direction of the second arm.

The prism apex angle sensor 12 detects the apex angle of each of the two glass plates of the active prism 11.

The prism control unit 13 is provided upright on the side surface of each glass plate so that each of the two glass plates of the active prism 11 can be displaced and driven in the yawing direction and the pitching direction. , Output signals from the first and second drive coils disposed in engagement with the second arm, the first and second photosensors of the prism apex angle sensor 12, and the correction signal generating means 2. And a drive control section that controls the drive voltage of the first and second drive coils by comparing the drive voltage with the corrected signal.

Based on the angle signal caused by camera shake in the yawing direction and the pitching direction of the video camera body detected by the prism control unit 13 via the first and second angular velocity sensors, the correction signal generating means 2 A comparator circuit compares the generated correction signal with the apex angle between the yawing direction and the pitching direction of each of the two glass plates of the active prism 11 detected through the first and second photosensors. Based on the comparison result, the drive control section controls the drive voltages of the first and second drive coils so as to drive the apex angle of each glass plate in the direction to cancel the shake.

As described above, the prism controller 13 can drive the apex angle of each of the two glass plates of the active prism 11 in the direction of canceling the camera shake.

In the correction means 3 having the above configuration, the correction signal is input to the prism control section 13 from the characteristic compensation filter 8 of the correction signal generation means 2. Further, the apex angle of each of the two glass plates of the active prism 11 is detected by the prism apex angle sensor 12, and the apex angle signal is input to the prism control unit 13. The prism controller 13 to which the correction signal and the apex angle signal are input changes the apex angle of the two glass plates in the direction in which the camera shake is canceled to correct the camera shake.

The fixed state detecting means 4 is supplied with the angular velocity signal output from the shake amount detecting means 1 after the low-pass component is cut by the high-pass filter 6 of the correction signal generating means 2, and the supplied angular velocity is supplied. The amplitude value of the signal is detected, and it is detected whether the amplitude value is equal to or less than a predetermined value and continued for a predetermined time. In a state where the amplitude value is equal to or less than a predetermined value and is continued for a predetermined time (hereinafter, referred to as a fixed mode), the video camera device is fixed on a tripod or the like and is imaged.

In the fixed state detecting means 4, for example, as shown in FIG.
, The amplitude value of the angular velocity signal is a predetermined threshold value SH.
When it is detected that the state of 1 or less continues for the predetermined time Ta, the detection signal indicating the fixed mode is output.

The compensation amount setting means 5 is supplied with the angular velocity signal output from the amount detecting means 1 after the low-pass component is cut by the high-pass filter 6 of the correction signal generating means 2, and the supplied angular velocity signal is supplied. Is set to the integral filter 7 so as to reduce the swing-back amount of the correction signal sent from the characteristic filter 8 of the correction signal generating means 2 when the amplitude value becomes larger than a predetermined value. Compensation value K _{0 for}
Is specified.

In the compensation amount setting means 5, for example, as shown in FIG. 3, after the fixed mode is detected by the fixed state detecting means 4, the amplitude value of the angular velocity signal is a predetermined threshold value SH2.
(However, when SH2> SH1) or more, as shown in FIG. 4, when the apex angle of the active prism 11 of the correction means 3 becomes zero, the correction means 3 is fixed in this state. As described above, the compensation value K ₀ of the integration filter 7 is set, and after the apex angle becomes zero, the setting of the compensation value K ₀ is canceled after a predetermined time Tb of, for example, about 0.3 seconds. Reduces the amount of swing back.

Alternatively, in the compensation amount setting means 5, when the amplitude value of the angular velocity signal exceeds a predetermined threshold value SH2,
The compensation value K ₀ of the integration filter 7 is set so as to reduce the feedback coefficient after the apex angle becomes zero, or the cutoff frequency after the apex angle becomes zero is integrated so as to shift to the high frequency side. It is also possible to reduce the swing-back amount of the correction signal by setting the compensation value K ₀ of the filter 7 and canceling the setting after a predetermined time Tb after the apex angle becomes zero.

In the image stabilization apparatus having the above-described structure, when the fixed state detecting means 4 detects the fixed photographing state and the shake amount detecting means 1 detects the shaking amount equal to or more than the threshold value SH2, the compensation amount is set. The setting means 5 sets the compensation value K ₀ of the integral filter 7 of the correction signal generating means 2 so as to reduce the amount of swing back of the correcting means 3.

For this reason, the correcting means 3 corrects the shaking of the image by reducing the amount of the shaking back when the shake exceeds the correction range of the correcting means 3 in the fixed shooting state, and the fixed shooting is performed. Even in the state, the image shake is naturally corrected.

In this embodiment, an example of the camera shake correction device is shown in which the angular velocity detection method is used as the shake amount detection means and the active prism method is used as the correction means. The present invention is not limited to the system, and the image stabilization apparatus of the present invention is a memory control system, a CCD drive control system, etc. when a camera shake is detected by a motion vector detection system or an angular velocity detection system such as a shake amount detecting means. Image stabilization method or a correction means using an optical processing method such as a gimbal mechanism method or an active prism method to correct camera shake, and does not cause "shaking" due to camera shake in the reproduced image, providing high image quality, small size, and light weight. It is possible to realize a type of video camera device.

[0065]

As described in detail above, in the camera shake correction apparatus of the present invention, after the fixed state detecting means detects that the fixed photographing state is set, the shake amount detecting means detects a shake amount of a predetermined amount or more. When detected, the compensation amount setting unit sets the compensation amount of the correction signal generation unit so as to reduce the swing-back amount of the correction unit.

For this reason, the correction means corrects the image shake by reducing the amount of shake return when shake occurs beyond the correction range of the corrector in the fixed shooting state, and in the fixed shooting state. It is possible to provide a camera shake correction device that naturally corrects image shake.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera shake correction device according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a main part of an integration filter provided in a correction signal generation unit of the image stabilization apparatus.

FIG. 3 is a characteristic diagram for explaining operations of a fixed state detecting unit and a compensation amount setting unit with respect to an angle signal detected by the shake amount detecting unit of the image stabilizing apparatus.

FIG. 4 is a characteristic diagram of an angle signal detected by a shake amount detection means of the camera shake correction device and an apex angle controlled by the correction means.

FIG. 5 is a characteristic diagram of an angle signal detected by a shake amount detection means of a conventional camera shake correction device and an apex angle controlled by the correction means.

[Explanation of symbols]

1 Shake amount detection means 2 correction signal generation means 3 correction means 4 Fixed state detection means 5 Compensation amount setting means 7 Integral filter

Claims (2)

(57) [Claims] 1. A shake amount detecting means for detecting a shake amount of an image caused by a shake of a video camera body, and a correction signal for correcting the shake of the image based on an output signal of the shake amount detecting means. A correction signal generating means for variably setting a compensation amount for generating the correction amount, a correction means for correcting the shake of the image according to the correction signal generated by the correction signal generating means, and a shake amount detecting means for detecting the shake. Fixed state detecting means for detecting whether or not the video camera body is in the fixed photographing state based on the shake amount, and the shake amount detecting means after the fixed state detecting means detects the fixed photographing state. A camera shake correction apparatus comprising: a compensation amount setting unit that sets a compensation amount of the correction signal so as to reduce the amount of the shake return of the correction unit when a shake amount of a fixed amount or more is detected. 2. The compensation amount setting means sets the compensation amount of the correction signal so as to reduce the swing-back amount of the correcting means after the center position of the correcting means.
The described image stabilization device.