KR100772384B1 - Apparatus for correcting image vibration of camera - Google Patents

Abstract

Disclosed is a novel improved image stabilization apparatus capable of accurately determining both and performing image stabilization in view of a change in angular velocity between panning / tilting and a hand shake operation. The image shake correction device according to the present invention comprises: an angle change value detector for detecting an angle change value of an imaging device; A derivative value calculating unit which calculates an nth order differential value by differentiating an angle change value of the photographing apparatus by a selectable order n (n is a positive integer); A correction target value determination unit that determines a target value for correcting the position of the image moved by the angle change of the photographing apparatus based on the nth derivative of the angle change value; And an image position corrector for correcting the position of the image moved by the angle change of the photographing apparatus according to the correction target value. By correcting the position of the image using the n-th order differential value, which is differentiated by the selectable order n to the angle change value of the photographing apparatus, it is possible to correct only the camera shake motion without responding to panning / tilting, thereby improving the quality of shooting. You can.

Description

Apparatus for correcting image vibration of camera

1 to 3 are explanatory diagrams for explaining the principle of the image stabilization apparatus according to an embodiment of the present invention.

4 is a block diagram showing the configuration of an image stabilization apparatus according to an embodiment of the present invention.

5 and 6 are explanatory views for explaining the operation of the image shake correction apparatus according to an embodiment of the present invention.

7 is a block diagram illustrating a configuration of an image shake correction device according to another exemplary embodiment of the present invention.

8 to 10 are explanatory views for explaining the operation of the image shake correction apparatus according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

102 .... Angular velocity detector 104 .... Integrator

106, 107 .... HPF (A) 108, 109 .... HPF (B)

110 .... DC component comparator 112 .... Switch

114 .... Actuator Position Target Value Converter

116 .... actuator position detector

118 .... Comparator 120 .... Servo Phase Compensator

122 .... Actuator Driver 124 .... Actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photographing, and more particularly, to image stabilization of a photographing apparatus such as a video camera or a still camera.

When a photographing device such as a video camera or a still camera is taken by a photographer with his hand, image shaking occurs due to hand shaking during unconsciousness. Various anti-shake devices have been proposed for correcting such unconscious image shaking.

In a typical anti-shake device, the angular velocity is detected by an angular velocity sensor mounted on the apparatus, and based on this, the positional shake of the image formed on the CCD is estimated. The anti-shake device has a mechanism capable of moving the correction lens in the lens glass cylinder, and moving the imaging point, calculating the movement amount of the correction lens from the estimated amount of image shake, and moving the correction lens to return the upper value. To realize.

However, in addition to unintended hand shaking, there is an angle change intentionally performed by the photographer, such as panning / tilting. Image stabilization is required to correct unintended angular changes and not to correct unintended angular changes. If this is not done, even though the photographer has intentionally moved the photographing device, the photographed image does not move. In addition, the panning / tilting has a large change in angle, and attempting to follow this causes a deflection of the correcting lens, and a problem of deterioration of the photographed image, which is unable to grasp the movable range for camera shake correction, also occurs. For this reason, in the anti-shake device, it is required to center the corrected lens as much as possible without responding to panning / tilting.

However, hand shake and panning / tilting are close in frequency and difficult to distinguish. For this reason, conventionally, when the angular velocity continues for more than a certain level and for a certain time, it is regarded as panning / tilting, and the correction sensitivity is reduced over the entire frequency in order not to respond to the panning / tilting, or until the camera shake correction region is performed. A cutoff frequency of a high pass filter is set (for example, see Japanese Patent Laid-Open No. 2003-219265). However, in such a configuration, there is a problem in that the camera shake correction capability is lost or noticeably degraded during panning / tilting.

The technical problem to be achieved by the present invention is not to distinguish between panning / tilting and hand shake only in the frequency domain as in the prior art, but focuses on the change in the angular velocity between panning / tilting and hand shake to accurately determine both to correct hand shake. It is to provide a novel and improved image stabilization device that can be performed.

Another object of the present invention is to provide a photographing apparatus including the image stabilization apparatus.

In order to solve the above problems, an image shake correction apparatus of an imaging apparatus includes: an angle change value detector configured to detect an angle change value of an imaging device; A derivative value calculating unit which calculates an nth order differential value by differentiating an angle change value of the photographing apparatus by a selectable order n (n is a positive integer); A correction target value determination unit that determines a target value for correcting the position of the image moved by the angle change of the photographing apparatus based on the nth derivative of the angle change value; And an image position corrector for correcting the position of the image moved by the angle change of the photographing apparatus according to the correction target value.

The differential value calculator includes one or more differentiators having the same order, and selects the order n by changing the connection state of the differentiators.

In addition, the differential value calculator selects a high value in order n to remove the panning / tilting component, and selects a low value in degree n when removing the shaking component.

The derivative value calculator further includes: a plurality of differential elements each of which generates an nth order differential value of the angle change value; And a derivative value comparator for comparing n-th derivatives of the plurality of derivatives to select n-th derivatives of the differential component having an optimal DC component removal performance. It is further preferred to include a low pass filter (LPF) for comparing the nth derivative of these.

In another embodiment, an image stabilization apparatus for achieving the above technical problem comprises: detecting means for detecting an angular change and / or an angular velocity change of an imaging system, an angular change output of the imaging system detected by the detection means, and And / or correction target value calculating means for calculating a correction target value based on the output of the angular velocity change, and correcting an upper value moved by the angle change of the photographing system based on the correction target value calculated by the correction target value calculating means. It is preferable to have an nth order differentiation element which includes a difference value correction means and can select an order.

It is also preferable that the selectable nth-order differential element is a differential element of the same order.

It is preferable that the differential element filter is of the same order and the other form of cutoff frequency is added to the conversion option at the time of DC component removal by the change of a simple step.

The change in angular velocity of panning / tilting is close to the normal velocity motion, and because of this, the change in angle is close to a simple increase function. For example, in the case of a linearly fluctuating function (slope function), the second derivative makes it zero. Even in the case of slightly complex movements, if it can be approximated by an n-th order polynomial function, it becomes 0 by the n + 1th derivative. On the other hand, hand shaking changes cosine function. The cosine function remains cosine by the second derivative. As in the related art, when the cutoff frequency of the HPF is simply increased, the jitter frequency component to be corrected is also removed at the same time. However, by adding the differential element and configuring the order of the differential element as in the present invention, it becomes possible to effectively suppress only the panning / tilting component by suppressing the influence on the original hand shake frequency. As a result, image stabilization can be performed accurately even during panning / tilting.

However, if the order of the differential element HPF is increased, the phase delay in the vicinity of the cutoff frequency fc increases even with the same cutoff frequency fc. In the camera shake correction, it is not preferable that the phase is delayed because a time lag occurs from the time when the imaging device changes the angle until the correction lens is moved. For this reason, when only the camera shake correction is performed, it is preferable to use the HPF at the lowest order and to convert to the higher order HPF in the case of panning / tilting. Therefore, the correction target value calculating means selects a relatively high order differential element when removing the panning / tilting component, selects a relatively low order differential element when removing the shaking component, and the correction target value is calculated. In such a configuration, image stabilization with less delay can be realized.

In addition, in order to select the order of the derivative elements, the n-th order differential element is composed of multiple elements of derivatives to which the same angular velocity change output is input, and the output of each system is compared to remove an optimal DC component for the input signal. The differential component with performance may be selected and configured to obtain a correction target value.

At this time, the output comparison of each system may be configured to be performed in accordance with each output moving average value, or may be configured to be performed in accordance with the pass output of the LPF. In this way, according to each output moving average value or the output of the LPF, by comparing each system output, it becomes possible to select a filter having an output in which the low frequency component of the position target value of the correction lens is closer to the instrument center level, Can be taken at the shooting position (optical design center position), and the quality of the shooting can be improved.

In addition, if the selective conversion of the differential elements is executed with a predetermined delay time, malfunction can be avoided and more accurate determination can be performed.

The selective conversion of the differential elements may be configured to be automatically converted, or the conversion switch capable of performing the selective conversion of the differential elements by the photographer may be provided and configured to be convertible by driving.

Furthermore, according to another aspect of the present invention, there is provided an imaging device having an image shake correction device having any one of the above features.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in the following description and drawing, the description which abbreviate | omit description is attached | subjected about the element which has a substantially same functional structure by attaching the same code | symbol.

First, the operation principle of the image stabilization apparatus based on this invention is demonstrated.

The camera shake, which is the subject of correction of the image stabilizer, is a reciprocating motion and is considered to be a sinusoidal vibration gathering. On the other hand, the panning / tilting excluded from the correction target of the image stabilization device is basically a motion of changing the angle in one direction, and is considered to be a ramp function or a higher-order polynomial motion.

First, consider the case of approximating panning / tilting as a ramp function.

이다. 여기서, s는 라플러스 연산자이다.The Laplace transform (L) of the ramp function is L =

to be. Where s is the Laplus operator.

이 된다.If this is the first derivative, the s component is multiplied,

Becomes

From the final value theorem on the Laplus transform,

Is not 0.

It can be seen that more than s ² action is required to converge to zero.

By the way, the transfer function G of the primary HPF is represented by the following equation. Where ω is the angular frequency.

G (s) =

HPF has a first derivative at the low end. Therefore, only one acting primary HPF can remove a component that is changing ramp function no matter how high the cutoff frequency (fc), but it acts twice or acts as a higher order HPF. In the case of action, it is possible to converge to zero.

Next, consider a case where the panning / tilting is approximated by a higher-order polynomial.

When approximated to an nth order polynomial, the Laplus transform (L) is

It can be seen that if there is more than s ^{n + 1} action, it can converge to zero.

1 shows the response to the slope input corresponding to panning / tilting. As shown, the slope input cannot be converged to zero only by the primary HPF operation, but it is possible to converge to zero by manipulating the secondary HPF. By manipulating the secondary HPF in this way it is possible to remove the panning / tilting component approximating the slope input.

On the other hand, since the sinusoidal wave approximating the shaking vibration which is the correction target is a single spectrum, it can be seen that when the cutoff frequency fc of the HPF is raised, the frequency is blocked by the cutoff frequency fc.

It is preferable that the control signal adopted by the image stabilizer according to the present embodiment does not respond to panning / tilting outside of the correction target even if it responds to the shaking of the correction target. In order to efficiently remove panning / tilting, it has been found that raising the order of the HPF is more effective than raising the cutoff frequency fc, as described above.

However, if the order of the HPF is raised, the phase delay near the cutoff frequency fc increases even with the same cutoff frequency fc. In image stabilization, it is not preferable that the phase is delayed because a time shift occurs from the time when the photographing apparatus changes the angle until the correction lens is moved. For this reason, when only the camera shake correction is performed, it is preferable to use the HPF at the lowest order and to convert to the higher order HPF in the case of panning / tilting.

Referring to FIGS. 2 and 3, a comparison is made for a response to a slope input approximating panning / tilting and a response to a sinusoidal input (l Hz) approximating hand shake. The HPF used here is of two types. Type A is the case where fc = 1 Hz HPF is used, and type B is the case where fc = 0.1 Hz HPF and two types of fc = 0.2 Hz HPF.

2 shows the response characteristics to the slope input. As shown in Fig. 2, when the input is on the slope, it does not converge to 0 in Type A, but converges in Type B. Thus, it can be seen that Type B secondary HPF is effective for removing the slope component corresponding to panning / tilting.

Figure 3 shows the response characteristics to the sinusoidal input. As shown in Fig. 3, the DC component is removed in the same manner as the type A configuration or the type B configuration, but the type B is closer to the original signal than the type A, and the amplitude is less attenuated. It can be seen that the configuration of B has desirable properties.

4 is a block diagram showing the configuration of an image stabilization apparatus according to an embodiment of the present invention. Referring to FIG. 4, the image shake correction device 100 according to the present embodiment includes an angular velocity detector 102 for detecting an angular velocity of an imaging device, an integrator 102 for angularly converting a detected angular velocity, DC component comparator to compare DC components of HPF (A) 106, HPF (B) 108 of system B, and HPF (A) 106 of system A and HPF (B) 108 of system B 110, the conversion switch 112 which performs conversion of the HPF (A) 106 of the system A and the HPF (B) 108 of the system B, and the position target value converter of the actuator driving the correction lens ( 114, the position detector 116 of the actuator for driving the correction lens, the comparator 118 for comparing the output of the position detector 116 and the position target value converter 114 of the actuator, and the servo control for controlling the actuator. The phase compensator 120, the actuator driver 122 which drives the actuator according to the servo command from the phase compensator 120, and the actuator which drives the correction lens. It is composed of 124.

In addition, in this embodiment, the angular velocity detector 102 and the integrator 104 correspond to the angle change value detector, and the HPF (A) 106 of the grid A, the HPF (B) 108 of the grid B, and the DC. The component comparator 110 and the exchange switch 112 correspond to the derivative value calculator, the position target value converter 114 of the actuator corresponds to the correction target value determiner, the position detector 116 of the actuator, the comparator ( 118, the servo phase compensator 120, the actuator driver 122, and the actuator 124 correspond to the phase position correction unit, but this should not be interpreted limitedly, and it is possible to employ various methods in various application states. Not to mention.

In this embodiment, a configuration is employed in which the HPF (A) 106 of the system A and the HPF (B) 108 of the system B are connected in series to change the response characteristics by changing the order of the HPF as a whole. For example, the system B can be configured to have a higher degree than the system A, and the panning / tilting component can be removed.

Figure 5 shows the output state of system A and system B for the slope input to which panning / tilting is approximated. As shown in the figure, since the phase delay is small in the case of the system A, it is excellent in the removal of the phase blur component that can obtain responsiveness, but it can be seen that the system B has an excellent ability of removing the panning / tilting component.

Therefore, at the time of operation, as shown in Fig. 6, the image shake correction operation can be performed. In other words, when panning / tilting occurs, the movement of the output low frequency is smaller on the system B relative to the system A. That is, when the operating frequency low frequency components of the system A and the system B are monitored, and a predetermined value or more is reached, panning / tilting has occurred, and this removal ability is converted to the system B having a high removal ability. In this case, it can be configured to return to the system A with less phase delay.

In addition, since noise and temporary angular output change are excluded, the system stability can be increased by adding a temporal factor to this determination and converting the output difference to a case where the output difference is recognized for a predetermined time.

In addition, in the image shake correction device 100 according to the embodiment shown in FIG. 4, the configuration in which the HPF 1006 of the system A and the HPF 1008 of the system B are connected in series is shown. Like the image shake correction device 150 according to the example, the HPF 107 of the system A and the HPF 109 of the system B may be connected in parallel. In addition, since it is the same about other elements and the operation | movement also in the case of embodiment shown in FIG. 4 or the embodiment shown in FIG. 7, detailed description is abbreviate | omitted.

In the above embodiment, the image stabilization device configured based on the present invention is described as an example employing a secondary or secondary HPF, but the present invention is not limited to this example. It goes without saying that the order or system tree of HPF can adopt various orders and system tree according to the use.

8 and 9, the operation of the hand shake correction apparatus employing the HPF configured of the third or third system will be described.

As shown in Fig. 8, the gain characteristics of the system A, the system B, and the system C are different from each other, and the DC component removal ability is low in the system A, and gradually increases in the system B, the system C. System C is large and becomes smaller as system B and system A go. As described above and repeated, HPF is preferable as the system A, and the lower the DC component removal ability, the less the influence on the signal of the hand shake frequency, but when the DC component of the HPF increases, as shown in FIG. Likewise, by converting sequentially to HPF of system B and system C with higher DC component removal capability, and returning to HPF of system A with low DC component removal capability when DC component is less, image shaking is always performed in an optimal state. Correction can be realized.

A conversion operation flow of the HPF shown in FIG. 9 will be described with reference to FIG. 10.

A signal indicating the state of the imaging device is always received from the angular velocity detector of the image stabilizer. Signals representing the state of the photographing apparatus are received and processed by the respective HPFs of the system A, system B, and system C, and the output DC components of the respective HPFs of system A, system B, and system C are compared. First, the DC component of HPF of system A and system B is compared (S10), and when it is below a predetermined value, the DC component of HPF of system B and system C is compared (S12). If the result is also less than or equal to the predetermined threshold, it is determined that the panning / tilting component is not included in the movement of the photographing apparatus, and the HPF of the A system which is optimal for image shake correction due to hand shake is selected (S14). Image stabilization is performed.

In step S10, the DC components of the HPFs of the system A and the system B are compared, and when judged to be equal to or more than a predetermined threshold, the DC components of the HPFs of the system B and the system C are compared in step S16. If the result is less than or equal to the predetermined threshold, the panning / tilting component is included in the movement of the photographing apparatus, and it is determined that it is not too large, and the HPF of the B system having a moderate removal performance of the panning / tilting component is selected. (S18), image stabilization is performed.

On the other hand, in step S12 and step S16, when the DC component of HPF of system B and system C compared compared with predetermined threshold value, the movement of an imaging device contains the panning / tilting component, Moreover, the action | action It is determined that this is large, and the HPF of the C system having a high removal performance of the original panning / tilting component is selected (S20), and image stabilization is performed.

By repeating the above operation, it is judged each time whether the panning / tilting component is included from the movement of the photographing apparatus, and if it is not included, the image stabilization by the sine wave approximable image stabilization is performed and included. If so, the optimum HPF is selected according to the size of the component, and image stabilization is performed after the panning / tilting component is removed.

As described above, according to the image stabilization apparatus according to the present embodiment, instead of distinguishing the panning / tilting and the hand shake only in the frequency domain as in the prior art, focusing on the change in the angular velocity of the panning / tilting and the hand shake operation. In this case, it is possible to accurately determine both of them and to correct camera shake.

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, this invention is not limited to this example. It will be clear to those skilled in the art that various modifications or modifications can be devised within the scope of the technical idea described in the claims, and those of course belong to the technical scope of the present invention.

For example, in the above embodiment, the HPF which automatically switches the order or system is adopted. However, since the original panning / tilting is performed by the user's intention, a manual switch is added to the outside of the imaging device, and the order of the HPF is changed. Alternatively, the system can be configured for manual conversion. According to this configuration, when the user intends to perform panning / tilting, it is possible to manually change the order or system of the HPF to a high removal performance of the panning / tilting component, so that image stabilization correction can be performed more reliably. .

It goes without saying that the user can adjust the feeling of operation by adjusting the order and cutoff frequency of the HPF.

Although the foregoing description has been focused on the novel features of the invention as applied to various embodiments, those skilled in the art will appreciate that the apparatus and method described above without departing from the scope of the invention. It will be understood that various deletions, substitutions, and changes in form and detail of the invention are possible. Accordingly, the scope of the invention is defined by the appended claims rather than in the foregoing description. All modifications within the scope of equivalents of the claims are to be embraced within the scope of the present invention.

As described above, according to the present invention, by correcting the position of the image by using the n-th order differential value obtained by differentiating the angle change value of the photographing apparatus to the selectable order n, only the camera shake operation is corrected without responding to panning / tilting. It is possible and can improve the quality of shooting.

Claims (7)

An angle change value detector configured to detect an angle change value of the photographing apparatus; A derivative value calculating unit which calculates an nth order differential value by differentiating an angle change value of the photographing apparatus by a selectable order n (n is a positive integer); A correction target value determination unit that determines a target value for correcting the position of the image moved by the angle change of the photographing apparatus based on the nth derivative of the angle change value; And And an image position corrector for correcting the position of the image moved by the angle change of the photographing apparatus according to the correction target value. The image blur correction apparatus of claim 1, wherein the differential value calculator comprises one or more differentiators having the same order, and selects the order n by changing the connection state of the differentiators. The method of claim 1, wherein the differential value calculation unit, The image stabilization apparatus of the photographing apparatus, wherein a high value is selected by order n when removing a panning / tilting component, and a low value is selected by order n when removing a hand shake component. The method of claim 1, wherein the differential value calculation unit, A plurality of differential elements each of which produces an nth derivative of the angle change value; And And a derivative value comparator for comparing the nth-order derivatives of the plurality of derivatives to select a derivative having an optimal DC component removal performance. The method of claim 4, wherein the differential value comparison unit, And a low pass filter (LPF) for comparing nth derivative values of the derivative elements. The method of claim 4, wherein the differential value comparison unit, As time progresses, a differential component having a higher DC component removal capability is sequentially selected when the DC component increases in the output of the differential component, and a differential component having a low DC component removal capability when the DC component decreases. The image stabilizer of the image pickup device, characterized in that for selecting. In the photographing apparatus, An angle change value detector for detecting an angle change value of the photographing apparatus; A derivative value calculating unit which calculates an nth order differential value by differentiating an angle change value of the photographing apparatus by a selectable order n (n is a positive integer); A correction target value determination unit that determines a target value for correcting the position of the image moved by the angle change of the photographing apparatus based on the nth derivative of the angle change value; And And an image position corrector for correcting the position of the image moved by the angle change of the photographing apparatus according to the correction target value.

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