Image blur suppression device and control method thereof

Abstract

To provide an image shake prevention device that can detect the occurrence of a phenomenon in which detection of vibration of an imaging apparatus and drive of a correction mechanism continue, and reduce the influence of the phenomenon, and a method for controlling the device.SOLUTION: An image shake prevention device moves a shake correction mechanism according to a shake of an imaging apparatus to prevent image shake, and has: control means that controls the movement of the shake correction mechanism to bring the deviation between a target position of the shake correction mechanism for correcting the shake and the current position of the shake correction mechanism closer to 0; detection means that detects vibration included in the shake and at a predetermined frequency that is higher than the frequency of vibration caused by camera shake; and changing means that, when the vibration at the predetermined frequency is detected, reduces a control gain when the movement of the shake correction mechanism is controlled compared to that when the vibration at the predetermined frequency is not detected.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image blur suppression device and a control method thereof. [Background technology]

[0002] Imaging device Movement There is known an image blur suppression device that suppresses image blur by driving a correction mechanism (for example, at least one of a correction lens and an image sensor) so as to cancel out the blur. As described in Patent Document 1, Imaging device Movement The detection and the drive of the correction mechanism are feedback-controlled to improve the accuracy of image blur suppression. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-66451 Summary of the Invention [Problem to be solved by the invention]

[0004] If there is a component mechanically connected to the housing of the imaging device, the micro-vibrations of the imaging device caused by the reaction of the drive of the correction mechanism may be amplified by that component. Typical examples of components that can amplify micro-vibrations include movable components connected to the housing of the imaging device via arms or hinges, external accessories attached to accessory shoes, and specific lens units (for example, interchangeable lenses whose total length and / or weight are equal to or greater than a threshold value).

[0005] When the minute vibration is amplified, the MovementA phenomenon in which detection and driving of the correction mechanism continue (hereinafter referred to as mechanical feedback (MFB)) may occur. When MFB occurs, the imaging device enters a state of continuous vibration. MFB differs from the feedback control oscillation phenomenon described in Patent Document 1 in that it can occur even when feedback control is stable and does not occur if vibration detection is stopped. Furthermore, no technology has been proposed to date for reducing MFB.

[0006] In one aspect, the present invention provides an imaging device Movement An image blur suppression device and a control method thereof are provided that can detect the occurrence of a phenomenon in which detection and driving of a correction mechanism continue, and reduce the influence of the phenomenon. [Means for solving the problem]

[0007] In one aspect, the present invention provides an image blur suppression device that suppresses image blur by moving a correction mechanism in accordance with movement of an imaging device, the image blur suppression device including: a control unit that controls the movement of the correction mechanism in accordance with a target position of the correction mechanism for suppressing image blur so as to bring a deviation from a current position of the correction mechanism closer to zero; a detection unit that detects vibrations of a predetermined frequency included in the movement and higher than a frequency of vibrations caused by camera shake; and a change unit that, when vibrations of the predetermined frequency are detected, reduces a control gain when controlling the movement of the correction mechanism compared to when vibrations of the predetermined frequency are not detected. When the imaging mode of the imaging device is switched, the change means returns the control gain to an initial value corresponding to the imaging mode after the switch. The present invention provides an image blur suppression device characterized by the above-mentioned. [Effects of the Invention]

[0008] According to the present invention, Movement It is possible to provide an image blur suppression device and a control method thereof that can detect the occurrence of a phenomenon in which detection and driving of a correction mechanism continue, and reduce the influence of the phenomenon. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a block diagram showing an example of the configuration of a digital camera, which is an example of an imaging device to which a shake suppression device according to an embodiment can be applied; [Figure 2] Schematic diagram showing the principle of mechanical feedback generation [Figure 3] Diagram of mechanical feedback detection process [Figure 4] Diagram for explaining the frequency detection method of mechanical feedback [Figure 5] Flowchart for image stabilization operation in an embodiment [Figure 6] 10 is a flowchart showing details of a control gain change process according to an embodiment. [Figure 7] 1 is a Bode diagram for an example of PID control according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below based on exemplary embodiments with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the claimed invention. Furthermore, although multiple features are described in the embodiments, not all of them are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] In the following embodiments, the present invention will be described with reference to an interchangeable-lens digital camera. However, the present invention can be implemented in any electronic device with an imaging function. Such electronic devices include video cameras, computer devices (personal computers, tablet computers, media players, PDAs, etc.), mobile phones, smartphones, game consoles, robots, drones, and drive recorders. These are merely examples, and the present invention can also be implemented in other electronic devices.

[0012] 1 is a block diagram showing an example of the functional configuration of an interchangeable lens digital camera 100 (hereinafter referred to as camera 100) capable of implementing an image blur suppression device according to an embodiment of the present invention. A detachable lens unit 101 is attached to the camera 100. The lens unit 101 may not be replaceable.

[0013] Lens unit 101 has multiple lenses, but FIG. 1 shows only focus lens 102. If a correction lens is used as a shake correction mechanism, the correction lens is also included in lens unit 101. Aperture 103 is a mechanical aperture with an adjustable aperture. Mechanical shutter 104 (hereinafter referred to as shutter 104) controls the exposure of image sensor 105. The shutter 104 and an electronic shutter may be used together, or only the electronic shutter may be used without the shutter 104.

[0014] The lens unit 101 forms an optical image of a subject on the image sensor 105. The image sensor 105 has a pixel array in which a plurality of pixels, each having a photoelectric conversion unit, are arranged two-dimensionally. The image sensor 105 converts the optical image of the subject into a group of pixel signals (analog image signals). The image sensor 105 may be a known CCD or CMOS image sensor.

[0015] In this embodiment, the image sensor 105 supports autofocus detection (phase difference AF) using an image plane phase difference detection method, and is capable of outputting a signal pair for phase difference AF.

[0016] In this embodiment, the image sensor 105 is configured to be movable, for example, in two directions perpendicular to the optical axis, and the image sensor 105 and its drive circuit function as a correction mechanism in the image blur suppression device. Note that the image sensor 105 may also be movable in other directions, for example, in a rotational direction around the optical axis.

[0017] Camera control unit 150 has one or more processors (CPU, MPU, etc.) capable of executing programs. Camera control unit 150 loads a program stored in storage memory 112, for example, into internal memory 110, executes the program, and controls the operations of camera 100 and lens unit 101, thereby realizing various functions of camera 100. Functions realized by camera control unit 150 include, for example, image stabilization control, automatic exposure (AE) control, and AF control.

[0018] 1, some of the functions realized by camera control unit 150 are shown as functional blocks 120 to 135. Therefore, matters described as the operations of functional blocks 120 to 135 are actually realized by camera control unit 150 executing a program. Furthermore, one or more of functional blocks 120 to 135 may be realized by hardware separate from camera control unit 150. Note that the image blur suppression device of this embodiment has a component indicated by 155.

[0019] The storage memory 112 is, for example, a rewritable nonvolatile memory, and stores programs executable by the camera control unit 150, various setting values, GUI data, and the like. The internal memory 110 is, for example, a volatile memory, and is used to load programs executed by the camera control unit 150 and to store values ​​required during program execution. In addition, a portion of the internal memory 110 is used as a video memory for the display unit 111.

[0020] When the lens unit 101 is detachable, the camera control unit 150 communicates with a lens control unit (not shown) of the lens unit 101 via the communication unit 116. Through communication with the lens unit 101, the camera control unit 150 controls the driving of the focus lens 102 and the diaphragm 103 and acquires information about the lens unit 101. Details of the operation of the camera control unit 150 will be described later.

[0021] The AD converter 106 generates a digital image signal by applying noise reduction processing, gain adjustment processing, and AD conversion processing to the analog image signal read out from the image sensor 105. The AD converter 106 outputs the generated digital image signal to the camera control unit 150, the phase difference AF signal processing unit 108, and the image processing circuit 109.

[0022] The timing generator 107 controls the drive timing of the image sensor 105 and the output timing of the AD converter 106 under the control of the camera control unit 150 .

[0023] The phase-difference AF signal processing unit 108 generates a pair of image signals (image signal A and image signal B) for phase-difference AF from the digital image signal output by the AD converter 106. The phase-difference AF signal processing unit 108 applies averaging processing to the generated pair of image signals to reduce the effects of noise, and then applies filtering processing to extract signal components in a predetermined frequency band. Furthermore, the phase-difference AF signal processing unit 108 calculates the amount of deviation (phase difference) between the signals that maximizes the correlation between the signals after filtering processing, and outputs the calculated amount to the focus control unit 131.

[0024] Focus control unit 131 converts the amount of deviation given by phase difference AF signal processing unit 108 into a defocus amount. Focus control unit 131 outputs the drive direction and drive amount of focus lens 102 based on the defocus amount to focus lens drive unit 130. Focus lens drive unit 130 drives focus lens 102 according to the drive direction and drive amount given from focus control unit 131. Note that if lens unit 101 is replaceable, the drive direction and drive amount of focus lens 102 may be notified to lens unit 101 via communication unit 116, and lens unit 101 may control the drive of focus lens 102.

[0025] The image processing circuit 109 applies color interpolation processing, correction processing, and the like to the digital image signal output by the AD converter 106 to generate a digital image signal for recording and / or display. The image processing circuit 109 stores the digital image signal for recording and / or display in an internal memory 110. Color interpolation processing is a process for interpolating values ​​of color components that cannot be obtained during shooting, and is also called demosaicing or synchronization processing. Correction processing includes white balance adjustment, gradation correction (gamma processing), processing for correcting the effects of optical aberration and vignetting of the lens unit 101, color correction processing, and the like. Note that these are examples of image processing that the image processing circuit 109 can apply, and do not limit the image processing that the image processing circuit 109 can apply.

[0026] The image processing circuit 109 synthesizes a digital image signal to be displayed on the display unit 111 with an image showing information about the camera 100 and stores the resulting signal in a video memory area of ​​the internal memory 110. The display unit 111 displays an image based on the image signal stored in the video memory area of ​​the internal memory 110. The display unit 111 may be, for example, a monitor fixed to the housing of the camera 100, or a variable-angle monitor connected to the housing via an arm or hinge and whose angle and orientation are variable.

[0027] The compression / decompression processing unit 114 generates coded image data by applying coding processing to the digital image signal stored in the internal memory 110. The compression / decompression processing unit 114 also applies decoding processing to the coded image data stored in the internal memory 110 to convert it into a digital image signal.

[0028] Operation unit 115 is a collective term for a group of input devices that allow the user to input instructions to camera 100. Operation unit 115 may include a release button, a shooting mode switching dial, a video shooting button, a shooting mode / playback mode switching button, directional keys, a confirm button, a menu button, and the like. If display unit 111 is a touch display, display unit 111 also functions as operation unit 115.

[0029] The shake detection unit 113 detects the movement of the camera 100. The shake detection unit 113 is, for example, a gyro sensor (hereinafter referred to as gyro), and detects, for example, angular velocity around three orthogonal axes including the optical axis direction and vertical direction of the camera 100.

[0030] The image pickup element driving unit 121 drives the moving mechanism of the image pickup element 105 . The image sensor position detection unit 120 detects the position of the image sensor 105. There are no particular limitations on the method for detecting the position of the image sensor 105, and any known method may be used, such as a magnetic method using a magnet and a Hall element, or an optical method using a light-emitting unit and a light-receiving sensor. Here, the image sensor 105 is assumed to have a movement mechanism that can move the image sensor 105 in a direction perpendicular to the optical axis.

[0031] The image sensor PID control unit 122 performs feedback control (for example, PID (ratio control, integral control, fine control) control) of the image sensor drive unit 121 in order to bring the deviation between the target position of the image sensor 105 and the current position detected by the image sensor position detection unit 120 closer to zero. Since PID control is a known technique, detailed description thereof will be omitted.

[0032] A luminance signal detector 135 generates luminance information used for automatic exposure control (AE) from the digital image signal output by the AD converter 106. The exposure control unit 134 determines the exposure conditions (shutter speed, aperture value, etc.) based on the luminance information obtained by the luminance signal detection unit 135. The exposure control unit 134 determines the exposure conditions (shutter speed, aperture value, etc.) based on the determined exposure conditions. of The shutter driver 132, the aperture driver 133, and the photographing condition determination unit 129 are notified.

[0033] The shutter driving unit 132 drives the shutter 104 in accordance with the shutter speed notified by the exposure control unit 134. The aperture driving unit 133 drives the aperture 103 in accordance with the aperture value notified by the exposure control unit 134. If the lens unit 101 is replaceable, the aperture value may be notified to the lens unit 101 via the communication unit 116, and the lens unit 101 may control the driving of the aperture 103. The exposure control unit 134 also controls the image sensor 105 mosquito The gain applied to the analog image signal read out from the image sensor is controlled.

[0034] Next, a description will be given of how the target position of the image sensor 105 is determined. Department It can be converted to an angle by integrating by 125. Department Since the angle obtained by 125 is minute, it can be converted into a position by multiplying it by a constant. This makes it possible to determine the target position of the image sensor 105 according to the angular velocity detected by the shake detection unit 113.

[0035] The shake correction calculation unit 124 multiplies the output value of the integration unit 125 by the lens sensitivity information acquired from the lens unit 101 via the communication unit 116 to calculate the shake correction amount. The lens sensitivity information is a value that changes depending on the focal length and in-focus distance of the lens unit 101. , Re Depending on the condition of the lens unit 101 Tare By multiplying the lens sensitivity information, an appropriate amount of shake correction for moving the image sensor 105 to the target position can be obtained.

[0036] The control gain change unit 123 changes the control gain in the image sensor PID control unit 122 based on the shake correction amount calculated by the shake correction calculation unit 124 and the change amount of the control gain notified by the MFB control gain management unit 126. The control gain change unit 123 can change the control gain, for example, by multiplying a constant corresponding to the change amount of the control gain with respect to the deviation feedback-controlled by the image sensor PID control unit 122. Increasing the control gain during feedback improves the tracking ability of the feedback control and improves the vibration isolation effect, but also increases the sensitivity to disturbances. On the other hand, decreasing the control gain during feedback reduces the tracking ability of the feedback control and reduces the vibration isolation effect, but also reduces the sensitivity to disturbances.

[0037] As described above, movable members connected to the housing via hinges or arms, such as a vari-angle monitor, and external accessories that can be attached to or detached from the housing's accessory shoe, have spring-like properties (spring components) at the connection points with the housing. Certain lens units (e.g., interchangeable lenses whose overall length and / or weight are equal to or greater than a threshold) also have spring components at the lens mount points.

[0038] FIG. 2 schematically shows a state in which an external flash is attached to the accessory shoe of camera 100. When the image stabilization mechanism (image sensor 105) is moved in response to the angular velocity detected by shake detection unit 113, a spring component generates a reaction vibration that is amplified. When shake detection unit 113 detects the amplified vibration as movement of camera 100, the image stabilization mechanism is moved to suppress the vibration. When the reaction to the movement of image sensor 105 is amplified by the spring component and detected by shake detection unit 113 in this way, a phenomenon known as mechanical feedback (MFB) occurs in which feedback control continues without converging. MFB occurs even when feedback control is stable, blurring the captured image and reducing image sharpness.

[0039] Fig. 3 is a diagram for explaining the configuration and operation of an image blur suppression device according to this embodiment. Here, it is assumed that MFB occurs in camera 100. The graph at the bottom of Fig. 3 schematically shows how the angular velocity signal output by shake detection unit 113 is handled in the processing process, with the horizontal axis representing time and the vertical axis representing angular velocity.

[0040] The shake detection unit 113 inputs an angular velocity signal (shake data) having a predetermined data rate to a bandpass filter (BPF) 128. The bandpass filter 128 can be realized by combining a highpass filter (HPF) 201 and a lowpass filter (LPF) 202. The BPF 128 is a filter that extracts the frequency components of the MFB. The frequency of the MFB coincides with a resonance frequency determined by a natural frequency that depends on the spring constant of the attachment portion of the external accessory or movable member. The resonance frequency varies depending on the type and number of external accessories and movable members. Therefore, multiple bandpass filters 128 with different passbands are used to extract the resonance frequency components for each combination of the type and number of external accessories and movable members.

[0041] The frequency of the MFB is higher than the frequency of vibrations due to camera shake (15 Hz or less), for example, 50 Hz or more. Therefore, the pass band of the bandpass filter 128 is a frequency band higher than the pass band for detecting vibrations due to camera shake.

[0042] The frequency of the generated MFB can also be identified by having the user input or automatically detecting information such as the open / closed state of the vari-angle monitor, the types of external accessories present, and the type of lens unit 101. If the frequency of the MFB can be identified, only the bandpass filter 128 that extracts the identified frequency component may be used. Also, instead of providing multiple bandpass filters 128 with fixed passbands, a variable bandpass filter may be used to reduce the number of bandpass filters 128.

[0043] The MFB determining section 127 has an amplitude level determining section 203 , a duration measuring section 204 , and a detected value determining section 205 , and is provided for each band pass filter 128 .

[0044] The amplitude level determining unit 203 calculates the frequency based on the number of times that the angular velocity of the MFB frequency component output from the BPF 128 exceeds or falls below a predetermined threshold. The operation of the amplitude level determining unit 203 will be described with reference to FIG.

[0045] 4(a) shows an example of the output signal of the band-pass filter 128. The band-pass filter 128 reduces noise components (frequency components other than the frequency component of the MFB to be extracted) contained in the output signal. Therefore, the frequency of the MFB can be calculated with high accuracy based on the number of times the upper threshold is exceeded and the number of times the lower threshold is exceeded within a certain period (which can also be considered the length of the period when the upper threshold is exceeded / fell below). Here, the upper threshold and the lower threshold have different signs and the same absolute value. Furthermore, the upper threshold and the lower threshold used by the amplitude level determination unit 203 may have different values ​​depending on the frequency component extracted by the corresponding band-pass filter 128.

[0046] On the other hand, Fig. 4(b) shows an example of an angular velocity signal (e.g., the output signal of the shake detection unit 113) when the band-pass filter 128 is not applied. In this case, the angular velocity signal contains a large amount of noise. Therefore, the accuracy of the MFB frequency calculated from the number of times the upper threshold value is exceeded and the number of times the lower threshold value is exceeded within a certain predetermined period is lower than that in the case of Fig. 4(a).

[0047] For example, suppose that the total number of times the upper threshold is exceeded and the number of times the lower threshold is exceeded within 200 ms is 15 or more, and the length of the period during which the upper threshold is exceeded and the period during which the lower threshold is exceeded corresponds to 95 Hz to 105 Hz. In this case, the amplitude level determining unit 203 determines that the candidate MFB frequency is 100 Hz. The upper and lower thresholds, 200 ms, and 15 times are preset values.

[0048] Returning to FIG. 3, the duration measurement unit 204 determines whether the frequency candidate determined by the amplitude level determination unit 203 continues for a predetermined time or a predetermined number of times. For example, it is assumed that the amplitude level determination unit 203 determines the frequency candidate of the MFB every 200 ms. In this case, the duration measurement unit 204 determines whether the amplitude level determination unit 203 has determined the same frequency candidate five times in a row (the candidate has continued for one second). The predetermined time or the predetermined number of times determined by the duration measurement unit 204 is set in advance.

[0049] If duration measurement unit 204 determines that amplitude level determination unit 203 has determined the same frequency candidate five times in a row (the candidate has continued for one second), detection value determination unit 205 determines that MFB of that frequency is occurring. When there are multiple detection value determination units 205 as shown in Figure 3, it may be determined that MFB of different frequencies is occurring simultaneously.

[0050] The MFB control gain management unit 126 determines the amount of change in the control gain according to the MFB frequency determined by the detection value determination unit 205, and notifies the control gain change unit 123. If MFB occurs, the MFB control gain management unit 126 reduces the control gain during feedback compared to when MFB does not occur, thereby reducing sensitivity to disturbances and suppressing the effect of MFB on feedback control. Furthermore, the MFB control gain management unit 126 changes the amount of reduction in the control gain according to the frequency of the occurring MFB (details will be described later). This makes it possible to suppress minute vibrations of the camera 100 caused by MFB, and ultimately a decrease in the sharpness of the captured image.

[0051] The shooting condition determination unit 129 notifies the MFB control gain management unit 126 to prohibit changes in the control gain when the operation unit 115 switches between the still image shooting mode and the video shooting mode, or when exposure for still image shooting or continuous shooting is in progress. This is because the control gain is returned to the initial value when switching between the still image shooting mode and the video shooting mode is performed. Also, changing the control gain during still image shooting may result in insufficient image stabilization.

[0052] Fig. 5 is a flowchart relating to the image shake correction operation performed by camera control unit 150 as an image shake suppression device. The image shake correction operation is performed periodically when image shake correction is enabled in camera 100. In Fig. 5, the processes of S104 to S114, which are performed periodically as the image shake correction operation, are shown as an anti-shake control loop.

[0053] In S104, the camera control unit 150 acquires the angular velocity signal (shake data) output from the shake detection unit 113. The camera control unit 150 may temporarily store the acquired angular velocity data in the internal memory 110. The acquired shake data is integrated. Department 125 and BPF128.

[0054] 5, the processes of S105 to S109 are shown to be performed in series, but the process of S105 and the processes of S106 to S107 can be performed in parallel. Note that, although two types of frequency components are extracted using three BPFs 128 with different passbands, there is no limit to the number of frequency components to be extracted.

[0055] In S105, the camera control unit 150 causes the integrating unit 125 to integrate the shake data and convert it into angle data. In S106, the camera control unit 150 performs BPF processing by applying each BPF 128 to the shake data. In S107, the camera control unit 150 determines whether or not MFB has occurred for each frequency component extracted by the BPF 128 using the amplitude level determination unit 203, the duration measurement unit 204, and the detection value determination unit 205, as described above.

[0056] In S110, the camera control unit 150 executes a control gain change process, which will be described in detail later with reference to FIG.

[0057] In S111 , the camera control unit 150 acquires the current position of the image sensor 105 from the image sensor position detection unit 120 . In S112, the camera control unit 150 calculates the deviation between the current position acquired in S111 and the target position calculated based on the integration processing result in S105.

[0058] In S113, the camera control unit 150 performs feedback control processing regarding the movement of the image sensor 105 by providing the deviation calculated in S112 to the image sensor PID control unit 122. In S114, the camera control unit 150 outputs to the image sensor driving unit 121 the drive amount determined by the image sensor PID control unit 122 in accordance with the deviation.

[0059] Next, the control gain change process performed in S110 will be described in detail with reference to the flowchart shown in FIG. In S202, the photographing condition determination unit 129 determines whether the photographing mode has been switched from one of the still image mode and the video mode to the other, and if it is determined that the mode has been switched, S203 is executed, and if not, S204 is executed.

[0060] In S203, the camera control unit 150 determines whether MFB occurred in the shooting mode before the switch. If it is determined that MFB occurred in the shooting mode before the switch, S210 is executed; if it is not determined that MFB occurred, the control gain is not changed and the control gain change process ends. The control gain may differ due to differences in the vibration reduction control characteristics between still image mode and video mode. When the shooting mode is switched, if MFB did not occur before the switch, the control gain was not changed when the previous shooting mode was switched, so there is no need to restore the control gain. On the other hand, if MFB occurred before the switch, the control gain was changed after the previous shooting mode was switched. Therefore, in S210, the camera control unit 150 changes the control gain to the initial value for the shooting mode after the switch and ends the control gain change process.

[0061] Fig. 7 is a Bode diagram relating to an example of control gain control in this embodiment. In the Bode diagram of Fig. 7, a phase diagram is shown on top and a gain diagram is shown on the bottom. The horizontal axis of the phase diagram represents frequency [Hz], and the vertical axis represents phase [deg]. The horizontal axis of the gain diagram represents frequency [Hz], and the vertical axis represents gain [dB]. The frequency on the horizontal axis is common to both diagrams.

[0062] In the gain diagram of Figure 7, the control gain when no MFB occurs in still image mode, shown by the solid line, is used as the reference, and the control gain in video mode, shown by the dotted line, is -10 dB from the reference. If MFB occurs in still image mode and the control gain is reduced by -7 dB from the reference, as shown by the dashed line, and then the mode is switched from still image mode to video mode, S210 reduces the control gain by an additional -3 dB. This makes the control gain -10 dB from the reference, returning it to its initial value in video mode.

[0063] 6, if it is determined in S202 that the shooting mode has not been switched, the shooting condition determination unit 129 determines in S204 whether exposure or continuous shooting is currently in progress in still image mode. If it is determined that exposure or continuous shooting is currently in progress in still image mode, the camera control unit 150 ends the control gain change process without changing the control gain. This is because changing the control gain during exposure or continuous shooting could affect image quality or result in differences in image quality between continuously shot images.

[0064] If it is not determined in S204 that exposure or continuous shooting is in progress in still image mode, the camera control unit 150 determines in S205 whether a predetermined time has elapsed since the most recent occurrence of MFB was determined. If it is not determined that the predetermined time has elapsed since the most recent occurrence of MFB was determined, or if the occurrence of MFB has not been determined, the camera control unit 150 ends the control gain change process without changing the control gain. On the other hand, if it is determined that the predetermined time has elapsed since the most recent occurrence of MFB was determined, the camera control unit 150 executes S206.

[0065] In S206, the camera control unit 150 determines whether it is determined in S107 or S109 that MFB has occurred. If it is not determined that MFB has occurred, the camera control unit 150 ends the control gain change process without changing the control gain. On the other hand, if it is determined in S107 or S109 that MFB has occurred, the camera control unit 150 executes S207.

[0066] In S207, the camera control unit 150 determines the amount of MFB gain change using the MFB control gain management unit 126. The MFB control gain management unit 126 determines the amount of gain change according to the frequency of MFB determined to be occurring by the MFB determination unit 127. For example, it is assumed that the two band-pass filters 128 have pass bands of 60 to 70 Hz, 120 to 140 Hz, and 190 to 205 Hz, respectively, as shown in FIG.

[0067] The gain change amount according to the MFB frequency is assumed to be as follows: When it is determined that MFB occurs between 60 and 70 Hz: -10 dB When it is determined that MFB occurs between 120 and 140 Hz: -9 dB When it is determined that MFB occurs between 190 and 205 Hz: -8 dB

[0068] If only one MFB determination unit 127 has determined that MFB has occurred, the MFB control gain management unit 126 determines the amount of gain change corresponding to the MFB frequency. On the other hand, if multiple MFB determination units 127 have determined that MFB has occurred, the MFB control gain management unit 126 determines the largest gain change amount among the gain change amounts corresponding to the MFB frequencies. For example, if it has been determined that MFB has occurred in all of the three frequency bands described above, the MFB control gain management unit 126 determines the amount of gain change to be −10 dB.

[0069] In S209, the camera control unit 150 changes the control gain of the image sensor PID control unit 122 using the control gain change unit 123 so that the control gain reflects the gain change amount notified by the MFB control gain management unit 126, and terminates the control gain change process.

[0070] According to this embodiment, it is possible to suppress continuous micro-vibrations (mechanical feedback: MFB) of the imaging device, which occur when vibrations of the imaging device caused by a reaction to the movement of the image stabilization mechanism are amplified by resonance. Specifically, when the occurrence of MFB is detected, MFB can be suppressed by reducing the control gain in the feedback control that controls the movement of the image stabilization mechanism. Furthermore, by varying the amount of reduction in the control gain depending on the MFB frequency, it is possible to achieve a balance between the image stabilization effect against camera shake and the suppression of MFB.

[0071] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0072] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to clarify the scope of the invention. [Explanation of symbols]

[0073] 100... interchangeable lens digital camera, 101... lens unit, 150... camera control unit, 155... blur suppression device

Claims

1. An image blur suppression device that suppresses image blur by moving a correction mechanism in accordance with the movement of an imaging device, a control means for controlling movement of the correction mechanism in accordance with a target position of the correction mechanism for suppressing the image blur so that a deviation between the target position and a current position of the correction mechanism approaches zero; a detection means for detecting vibrations of a predetermined frequency that is higher than the frequency of vibrations caused by hand shake, which are included in the movement; a change unit that, when vibration of the predetermined frequency is detected, reduces a control gain used to control movement of the correction mechanism compared to a case where vibration of the predetermined frequency is not detected; and and 10. An image blur suppression device according to claim 9, wherein, when the imaging mode of the imaging device is switched, the change unit returns the control gain to an initial value corresponding to the imaging mode after the switch.

2. An image blur suppression device as described in claim 1, characterized in that the initial value differs between still image mode and video mode, and is a lower value in video mode than in still image mode.

3. An image blur suppression device that suppresses image blur by moving a correction mechanism in accordance with the movement of an imaging device, a control means for controlling movement of the correction mechanism in accordance with a target position of the correction mechanism for suppressing the image blur so that a deviation between the target position and a current position of the correction mechanism approaches zero; a detection means for detecting vibrations of a predetermined frequency that is higher than the frequency of vibrations caused by hand shake, which are included in the movement; a change unit that, when vibration of the predetermined frequency is detected, reduces a control gain used to control movement of the correction mechanism compared to a case where vibration of the predetermined frequency is not detected; and and An image blur suppression device, characterized in that the control gain is not changed during exposure for still image shooting or during continuous shooting.

4. 4. The image blur suppression device according to claim 1, wherein the predetermined frequency is higher than 15 Hz.

5. 5. The image blur suppression device according to claim 1, wherein the predetermined frequency is based on a resonance frequency of a member attached to the imaging device.

6. 6. The image blur suppression device according to claim 5, wherein a connecting portion between the member and the imaging device has a spring-like property.

7. 7. The image blur suppression device according to claim 5, wherein the member is a movable member attached to a housing of the image pickup device via a hinge or an arm.

8. 8. The image blur suppression device according to claim 5, wherein the member is an external accessory that is detachable from the imaging device.

9. 9. The image blur suppression device according to claim 1, wherein the detection means detects vibrations of the predetermined frequency based on the number of times that the angular velocity of the imaging device exceeds or falls below a threshold within a predetermined period.

10. 10. The image blur suppression device according to claim 1, wherein the correction mechanism includes an image sensor.

11. An imaging device comprising the image blur suppression device according to any one of claims 1 to 10.

12. A control method for an image blur suppression device that suppresses image blur by moving a correction mechanism in accordance with movement of an imaging device, comprising: a control step of controlling movement of the correction mechanism so that a deviation between a target position of the correction mechanism for suppressing the image blur and a current position of the correction mechanism approaches zero; a detection step of detecting vibrations of a predetermined frequency that is higher than the frequency of vibrations caused by camera shake, which are included in the movement; a changing step of reducing a control gain for controlling movement of the correction mechanism when vibration of the predetermined frequency is detected, compared to when vibration of the predetermined frequency is not detected; a restoring step of restoring the control gain to an initial value corresponding to the imaging mode after switching when the imaging mode of the imaging device is switched; 1. A method for controlling an image blur suppression device, comprising:

13. A control method for an image blur suppression device that suppresses image blur by moving a correction mechanism in accordance with movement of an imaging device, comprising: a control step of controlling movement of the correction mechanism so that a deviation between a target position of the correction mechanism for suppressing the image blur and a current position of the correction mechanism approaches zero; a detection step of detecting vibrations of a predetermined frequency that is higher than the frequency of vibrations caused by camera shake, which are included in the movement; a changing step of reducing a control gain for controlling movement of the correction mechanism when vibration of the predetermined frequency is detected, compared to when vibration of the predetermined frequency is not detected; and The control method for an image blur suppression device, wherein the changing step does not change the control gain during exposure for still image shooting or during continuous shooting.

14. A program for causing a computer to function as each of the means included in the image blur suppression device according to any one of claims 1 to 10.

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