JP6327838B2 - Image shake correction apparatus, control method therefor, optical apparatus, and imaging apparatus - Google Patents

Description

  The present invention relates to an image blur correction technique in which image blur that may occur due to camera shake or the like is corrected by a plurality of correction units.

2. Description of the Related Art There is known an image blur correction device that detects a shake of an imaging device and drives and controls an optical member to correct an image blur caused by the shake. A correction function of a method of driving an optical member such as a correction lens is called optical image shake correction.
In the image blur correction apparatus disclosed in Patent Document 1, a first movable lens barrel that holds a first correction member and a second movable lens barrel that holds a second correction member are arranged on both sides of a fixed member. Thus, each movable barrel can be driven independently. Thereby, the angle range in which image blur correction can be performed can be increased.

JP 2009-258389 A

  Generally, in disturbance compensation for a controlled object, the transfer function is theoretically obtained from the inverse model of the actual controlled object, and the output from the actual controlled object is input, and the input signal to the controlled object (disturbance is reduced). Including). The disturbance is calculated by subtracting the input signal to the controlled object from the estimated signal including the disturbance. The disturbance obtained by the estimation can be subtracted from the input signal to the controlled object to suppress the disturbance input.

However, the estimation accuracy of the disturbance depends on the detection accuracy of the output signal to be controlled. That is, when the resolution is low, the estimation accuracy of the disturbance is also low. In two independent control objects such as Patent Document 1, when the resolution of driving position detection is the same, the driving stroke is different due to the difference in optical sensitivity. Therefore, a difference occurs in detection resolution with respect to the drive stroke. When general disturbance compensation is performed on two independent control objects, the accuracy of disturbance compensation is high in one control object, but the accuracy of disturbance compensation is low in the other control object.
An object of the present invention is to improve robustness by suppressing deterioration in the accuracy of disturbance compensation related to a plurality of correction means in an image shake correction apparatus that corrects image blur using a plurality of correction means.

In order to solve the above-described problems, an apparatus according to the present invention is an image shake correction apparatus that corrects an image shake by the first optical correction unit and the second optical correction unit, and the shake detected by the shake detection unit. A calculation means for obtaining a detection signal and calculating a target position of the first optical correction means and a target position of the second optical correction means; a position of the first optical correction means; and a second optical correction. position detecting means for detecting the position of means, the position of the first optical compensation means, a first control means for performing feedback control to converge to the target position where the calculating means is calculated, the second optical compensation means The second control means for performing feedback control for converging the position to the target position calculated by the calculation means, the first disturbance estimation means for calculating the disturbance to the first optical correction means, and the second optical Calculate the disturbance to the correction means A second disturbance estimating means; a first disturbance compensating means for performing disturbance compensation for the first control means by subtracting an output of the first disturbance estimating means from an output of the first control means; and By subtracting the output of the second disturbance estimation means from the output of the control means, a second disturbance compensation means for compensating for the disturbance to the second control means, the estimation accuracy of the first disturbance estimation means, and the second When the estimation accuracy of the limiter unit that determines the estimation accuracy of the disturbance estimation unit and the second disturbance estimation unit is higher than that of the first disturbance estimation unit, the first calculation data by the first disturbance estimation unit is Mask means for masking lower bits less than or equal to a threshold determined by the limiter means, and signals of lower bits less than or equal to the threshold in the second operation data by the second disturbance estimation means Having, adding means for adding the output of the unit.

  According to the present invention, in an image blur correction apparatus that corrects image blur using a plurality of correction units, it is possible to improve robustness by suppressing a decrease in the accuracy of disturbance compensation related to the plurality of correction units.

It is a block diagram which shows the structural example of the imaging device which concerns on embodiment of this invention. FIG. 3 is a block diagram illustrating an image blur correction control unit according to an embodiment of the present invention. It is a block diagram explaining a disturbance observer. It is a block diagram which shows the structural example at the time of applying a disturbance observer to a shake correction control part. It is a block diagram which shows the structural example of the 1st and 2nd shake correction control part which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, an image pickup apparatus that corrects image shake of an image picked up by an image pickup device using a plurality of correction units is illustrated. A plurality of correction means for correcting the image shake according to the shake detection information of the apparatus are movable optical members constituting the imaging optical system.

FIG. 1 is a block diagram illustrating a configuration example of an imaging apparatus according to the present embodiment. This imaging apparatus is a digital camera that mainly captures still images and moving images.
The zoom unit 101 includes a zoom lens that performs zooming. The zoom drive control unit 102 drives and controls the zoom unit 101. The first image shake correction unit 103 includes a first optical member that changes the relative position between the subject image and the image sensor in the imaging plane. The first optical member is, for example, a correction lens (shift lens) that can move in a direction orthogonal to the optical axis of the imaging optical system. The first image blur correction control unit 104 drives and controls the first image blur correction unit 103. The second image shake correction unit 105 includes a second optical member that changes the relative position between the subject image and the image sensor in the imaging plane. The second optical member is, for example, a correction lens (shift lens) that can move in a direction orthogonal to the optical axis of the imaging optical system. The second image blur correction control unit 106 controls driving of the second image blur correction unit. The aperture / shutter unit 107 includes an aperture and a shutter. The aperture / shutter drive control unit 108 controls the drive of the aperture / shutter unit 107. The focus unit 109 includes a focus lens that performs focus adjustment. The focus drive control unit 110 drives and controls the focus unit 109.

  The imaging unit 111 includes an imaging element, and converts light imaged through each lens group into an electrical signal by photoelectric conversion. The imaging signal processing unit 112 converts the electrical signal output from the imaging unit 111 into a video signal. The video signal processing unit 113 acquires the video signal output from the imaging signal processing unit 112 and processes it according to the application. The display unit 114 performs image display as necessary based on the signal output from the video signal processing unit 113. The power supply unit 115 supplies power to the components of the camera system according to the application. The external input / output terminal unit 116 is used for input / output of communication signals and video signals with an external device. The operation unit 117 is used by the user for camera operation, and outputs an operation instruction signal to the camera system control unit 120. The storage unit 118 stores various data such as video information. The shake detection unit 119 detects a shake amount applied to the imaging apparatus and outputs a shake detection signal to the camera system control unit 120. The camera system control unit 120 that controls the entire system includes a CPU (Central Processing Unit) and the like, and controls the camera operation by executing a program read from the memory. For example, the camera system control unit 120 transmits a control command to the zoom drive control unit 102 to perform zoom drive control, and transmits a control command to the first image blur correction control unit 104 and the second image blur correction control unit 106. Image blur correction control. The camera system control unit 120 transmits a control command to the aperture / shutter drive control unit 108 to control aperture adjustment and shutter drive, and transmits a control command to the focus drive control unit 110 to perform focus adjustment control. Note that a recording processing unit or the like for recording the captured image on a recording medium is provided, but a description of components that are not directly related to the present invention is omitted.

Next, a schematic operation of the imaging apparatus having the above configuration will be described.
The operation unit 117 includes an image stabilization ON / OFF switch that enables image blur correction ON / OFF to be selected. When image blur correction ON is selected by the image stabilization switch, the camera system control unit 120 instructs the first image blur control unit 104 and the second image blur control unit 106 to perform an image blur correction operation. Upon receiving this instruction, the first image blur correction control unit 104 and the second image blur correction control unit 106 continue the image blur correction operation until an OFF instruction is issued.

  The operation unit 117 includes a shutter release switch configured such that the first switch (SW1) and the second switch (SW2) are sequentially turned on in accordance with the push amount. The switch SW1 is turned on when the shutter release button is depressed about half, and the switch SW2 is turned on when the shutter release button is pushed down to the end. When the switch SW1 is turned on, the focus drive control unit 110 drives the focus unit 109 to perform focus adjustment, and the aperture / shutter drive control unit 108 drives the aperture / shutter unit 107 to set an appropriate exposure amount. To do. When the switch SW2 is turned on, image data obtained from the light image exposed to the imaging unit 111 is stored in the storage unit 118.

The operation unit 117 includes a moving image recording switch. Moving image recording starts after the moving image recording switch is pressed, and recording is ended when the switch is pressed again during recording. When SW1 and SW2 are operated during moving image shooting, still image shooting during moving image recording can be handled. The operation unit 117 also includes a reproduction mode selection switch for selecting a reproduction mode, and the image stabilization operation is stopped in the reproduction mode.
The operation unit 117 includes a zoom switch for instructing zoom zoom. When an instruction for zooming magnification is given by the zooming switch, the zoom drive control unit 102 that has received the instruction via the camera system control unit 120 drives the zoom unit 101 and moves the zoom unit 101 to the instructed zoom position. Let At the same time, the focus drive control unit 110 drives the focus unit 109 to perform focus adjustment based on the image information processed by the signal processing units (112, 113) sent from the imaging unit 111.

  FIG. 2 is a block diagram illustrating the relationship between the first and second image blur correction control units 104 and 106 and the camera system control unit 120 in more detail. In addition, since it becomes the same structure in a pitch (Pitch) direction and a yaw (Yaw) direction, only one axis | shaft is demonstrated. The first image blur correction control unit 104 and the second image blur correction control unit 106 have the same configuration, and hence the latter description is omitted.

  The shake detection unit 119 detects angular velocity data using a gyro sensor or the like, and outputs a shake detection voltage. An angular velocity detection AD (Analog to Digital) conversion unit 201 converts the output voltage of the shake detection unit 119 into digital data and outputs the digital data to an HPF (High Pass Filter) 202. The HPF 202 removes an offset component and a temperature drift component included in the angular velocity data indicated by the shake detection signal. An LPF (low-pass filter) 203 integrates angular velocity data and converts it into angle data. The shake correction sensitivity multiplication unit 204 multiplies the angle data by the sensitivity, and converts the angle data into a shift amount (movement amount) of the shake correction lens. This sensitivity has a different value for each focal length, and the sensitivity changes as the focal length changes. The output switching unit 205 switches the output in response to the shake correction ON (operation) command or OFF (non-operation) command from the operation unit 117. That is, in the case of an OFF command, the output is forcibly stopped. A limiter 206 for the shake correction amount clamps the image shake correction amount within a range that satisfies the optical performance, and outputs the clamped amount to the subtraction unit DEC. The subtraction unit DEC subtracts an output of an AD conversion unit 211 described later from the output of the limiter 206, and outputs a subtraction result.

The PID control unit 207 is a controller for controlling the position of the image blur correction lens. The PID control unit 207 executes each calculation related to P (proportional) control, I (integral) control, and D (differential) control according to the output of the subtracting unit DEC, and outputs a signal indicating an image blur correction amount to the driver unit. It outputs to 208. The PID control unit 207 constitutes a feedback control loop that converges the position of the image shake correction lens 209 of the first shake correction unit 103 detected by the position detection unit 210 to the target position.
The driver unit 208 converts the image blur correction amount signal into a voltage, and supplies a current for driving the image blur correction lens 209 to the actuator coil. The image blur correction lens 209 is a shift lens that forms part of the imaging optical system and moves on a plane perpendicular to the optical axis. The image blur correction lens 209 is moved by energization of the actuator coil to optically correct the image blur. The position detection unit 210 detects the position of the image blur correction lens 209 and outputs a detection voltage corresponding to the position detection information. The AD conversion unit 211 converts the position detection voltage (analog voltage) of the image blur correction lens 209 into digital data, and then outputs the digital data to the subtraction unit DEC.

Next, a general disturbance observer will be described with reference to FIG. The following quantities are defined.
U: Input to the control target 301 (before receiving a disturbance).
Y: Output of the control target 301
G (s): Transfer function of the control target 301.
D: Disturbance applied to the control target 301.
H (s): The transfer function of the controlled object 301 obtained theoretically.
E: Estimated disturbance.

In general, when the controlled object has a mechanical structure, the transfer function G (s) of the controlled object has a nonlinear component, so it is difficult to match the theoretically obtained transfer function H (s). Therefore, although G (s) ≈H (s), strictly speaking, G (s) ≠ H (s). The input to the control target 301 is the sum of the input u from the control unit and the disturbance d (see the adding unit 303). In the control object 301, an output is generated according to the input. By inputting the output y to the inverse model 302 of the transfer function of the controlled object 301 obtained theoretically, the estimation process of the input signal input to the controlled object 301 is performed. As described above, since G (s) ≈H (s), the input does not exactly match the actual input. Therefore, this input is only an estimated signal. Since the estimated input is estimated as the sum of the input u from the control unit and the disturbance d, the disturbance is obtained by subtracting the input signal u from the actual control unit from the estimated input signal (see the subtraction unit 305). Can be estimated. The estimated disturbance e is subtracted in advance from the input u from the control unit (see subtraction unit 304), so that the actual disturbance applied later is compensated. The disturbance observer includes an inverse model 302 and a subtraction unit 305 indicated by a transfer function “1 / H (s)”.
From the above, it can be seen that the estimation accuracy of the disturbance depends on the approximation accuracy of the transfer function of the inverse model 302 of the controlled object 301 and the resolution of the observable input / output signals.

Next, with reference to FIG. 4, a configuration example in the case where the disturbance observer is applied to the shake correction control unit will be described.
First, the input signal is sent to the PID control unit 207 via the subtraction unit DEC1. The output of the PID control unit 207 is output to the driver unit 208 and the disturbance observer 401 via the subtraction unit DEC2. The first shake correction unit 103 is driven by a drive signal (current) output from the driver unit 208. At this time, when a disturbance (mainly acceleration disturbance) is applied to the first shake correction unit 103 that is a control target, the movement includes the disturbance. This movement is detected by the position detection unit 210. The AD converter 211 converts the position detection signal into digital data. The AD-converted position detection signal is output to the disturbance observer 401 and the subtraction unit DEC1.

  The disturbance observer 401 estimates a disturbance by subtracting a control command signal that does not include an actual disturbance from the AD-converted position signal. Disturbance compensation processing is executed by outputting the calculation result to the subtraction unit DEC2. The subtractor DEC1 outputs a signal obtained by subtracting the output signal of the AD converter 211 from the input signal to the PID controller 207. The subtraction unit DEC2 subtracts the output signal of the disturbance observer 401 from the output signal of the PID control unit 207, and outputs a signal after the subtraction.

  Next, details of the first shake correction control unit 104 and the second shake correction control unit 106 will be described with reference to FIG. As an example, it is assumed that the first shake correction unit 103 has a larger drive stroke than the second shake correction unit 105 and the resolution of the position detection signal is lower. In the configuration example of FIG. 5, each disturbance observer is provided for the control unit that controls the first shake correction unit 103 and the second shake correction unit 105. A plurality of disturbance compensation units are provided that perform disturbance compensation by subtracting the output of the disturbance observer from the output of each control unit.

  In the first shake correction control unit 104, the output of the first AD conversion unit 504 is subtracted from the input signal by the subtraction unit DEC 41 and sent to the first control unit 501. The input signal to the subtraction unit DEC41 is a target position signal related to the drive control of the first shake correction unit 103 calculated by the camera system control unit 120 in accordance with the shake detection signal from the shake detection unit 119.

The first control unit 501 constitutes a feedback control loop that converges the position of the image shake correction lens of the first shake correction unit 103 to the target position. The control output of the first control unit 501 is sent to the subtraction unit DEC42 (first subtraction unit), and the output of the first gain unit 507 is subtracted. The output of the subtraction unit DEC42 is sent to the first driver unit 502 and the first disturbance observer 505. The first shake correction unit 103 is driven according to the output of the first driver unit 502, and the first position detection unit 503 performs position detection. The position detection signal is sent to the subtraction unit DEC41 and the first disturbance observer 505 after the first AD conversion unit 504 converts it into a digital signal. The subtraction unit DEC42, the first gain unit 507, a mask unit 506, which will be described later, an addition unit ADD, an estimated disturbance limiter 514, and the like constitute a first disturbance compensation unit.
In the second shake correction control unit 106, the output of the second AD conversion unit 511 is subtracted from the input signal by the subtraction unit DEC 61 and sent to the second control unit 501. The input signal to the subtraction unit DEC 61 is a target position signal related to the drive control of the second shake correction unit 105 calculated by the camera system control unit 120 in accordance with the shake detection signal from the shake detection unit 119.

  The second control unit 501 constitutes a feedback control loop that converges the position of the image shake correction lens of the second shake correction unit 105 to the target position. The control output of the second control unit 501 is sent to the subtraction unit DEC62 (second subtraction unit), and the output of the second gain unit 513 is subtracted. The output of the subtraction unit DEC62 is sent to the second driver unit 502 and the second disturbance observer 512. The second shake correction unit 105 is driven according to the output of the second driver unit 509, and the second position detection unit 510 detects the position. The position detection signal is converted into a digital signal by the second AD converter 511 and then sent to the subtractor DEC 61 and the second disturbance observer 512. The calculation output of the second disturbance observer 512 is sent to the second gain unit 513 and the estimated disturbance limiter 514. The output after the gain coefficient is multiplied by the second gain unit 513 is output to the subtraction unit DEC62. The second gain unit 513 and the subtraction unit DEC62 constitute a second disturbance compensation unit.

  The estimated disturbance (first calculation data) that is the output of the first disturbance observer 505 is less accurate than the estimated disturbance (second calculation data) that is the output of the second disturbance observer 512. For this reason, it is assumed that the low-order bits of the estimated disturbance, which is the output of the first disturbance observer 505, is noise. When the disturbance compensation is performed using the estimated disturbance including the noise, there is a possibility of causing a minute driving noise due to the superimposed noise. Therefore, the mask unit 506 masks the lower bits of the output of the first disturbance observer 505 with low accuracy as noise. That is, since the lower bits below the threshold determined by the estimated disturbance limiter 514 are masked with respect to the first calculation data by the first disturbance observer 505, the lower bit data is not used. The output of the mask unit 506 is sent to the adding unit ADD.

  The estimated disturbance limiter 514 performs limit processing on the highly accurate disturbance estimation output (second calculation data) calculated by the second disturbance observer 512 and outputs the result to the adder ADD. That is, lower bits below the threshold in the second calculation data by the second disturbance observer 512 are extracted. The adder ADD adds the output after the limit process to the output of the first disturbance observer 505 with low accuracy by the mask unit 506. The output of the adding unit ADD is output to the subtracting unit DEC42 after being multiplied by the gain coefficient in the first gain unit 507. Thereby, both the 1st disturbance compensation part and the 2nd disturbance compensation part can realize high accuracy.

  In this embodiment, a gain adjustment unit 515 is further provided. The gain adjustment unit 515 acquires the calculation data of the first and second disturbance observers, and adjusts the gain coefficients of the first gain unit 507 and the second gain unit 513, respectively. The gain adjustment unit 515 compares the estimated disturbance of higher-order bits that is not a noise component between the first estimated disturbance and the second estimated disturbance, and each gain coefficient of the first gain unit 507 and the second gain unit 513 according to the difference. Switch. Since the disturbance is in the same imaging device, it is assumed that the first bit estimated value and the second disturbance estimated value do not exactly match, but the upper bits are close to each other. Therefore, the gain adjustment unit 515 calculates the difference between the first estimated disturbance and the second estimated disturbance. The gain coefficient of the first gain unit 507 and the second gain unit 513 is controlled to a value closer to 1 as the difference is smaller, and each gain coefficient is controlled to a smaller value as the difference is larger, and processing for weakening disturbance compensation is executed. Is done. Thereby, it is possible to prevent malfunction of the correction lens due to erroneous estimation of disturbance.

  Further, as shown in FIG. 5, a limiter changing unit 516 that changes the threshold value of the estimated disturbance limiter 514 is provided. The limiter changing unit 516 acquires the position detection information of the zoom unit 101 and controls the threshold value of the estimated disturbance limiter 514 according to the focal length. For example, the estimation accuracy of the first disturbance observer 505 can be set low by increasing the mask level by increasing the threshold. It should be noted that since the zoom drive control unit 102 is known about the drive unit that performs zoom drive of the imaging optical system and the acquisition of focal length information, a detailed description thereof is omitted.

  According to the present embodiment, in an imaging apparatus including a plurality of image blur correction units, it is possible to perform control while suppressing degradation in accuracy of disturbance compensation for each image blur correction unit, and to improve robustness. In the present embodiment, an example in which two systems of image shake correction means are used has been described. However, the present invention provides an image pickup apparatus and various optical devices (lens barrels, lens devices, binoculars, etc.) having three or more image shake correction means. ).

DESCRIPTION OF SYMBOLS 103 1st image shake correction unit 104 1st image shake correction control part 105 2nd image shake correction unit 106 2nd image shake correction control part 111 Imaging part 119 Shake detection part 120 Camera system control part

Claims (7)

An image blur correction apparatus that corrects image blur by a first optical correction unit and a second optical correction unit ,
Calculating means for obtaining a shake detection signal detected by the shake detection means and calculating a target position of the first optical correction means and a target position of the second optical correction means ;
Position detection means for detecting the position of the first optical correction means and the position of the second optical correction means ;
First control means for performing feedback control for converging the position of the first optical correction means to the target position calculated by the calculation means;
Second control means for performing feedback control for converging the position of the second optical correction means to the target position calculated by the calculation means;
First disturbance estimation means for calculating a disturbance to the first optical correction means;
Second disturbance estimation means for calculating a disturbance to the second optical correction means;
First disturbance compensation means for performing disturbance compensation on the first control means by subtracting the output of the first disturbance estimation means from the output of the first control means;
Second disturbance compensation means for performing disturbance compensation for the second control means by subtracting the output of the second disturbance estimation means from the output of the second control means;
Limiter means for determining the estimation accuracy of the first disturbance estimation means and the estimation accuracy of the second disturbance estimation means;
When the second disturbance estimation means has higher estimation accuracy than the first disturbance estimation means, the lower-order bits below the threshold value determined by the limiter means are applied to the first calculation data by the first disturbance estimation means. Mask means for masking;
An image blur correction apparatus comprising: addition means for adding a signal of lower bits not more than the threshold in the second calculation data by the second disturbance estimation means to the output of the mask means . Image blur correction according to claim 1, characterized in that it comprises a gain adjusting means for changing the gain of the first operation data and second operation data by comparing the second operation data and the first operation data apparatus. The first disturbance compensation means,
First gain means whose gain coefficient is changed by the gain adjusting means;
First subtracting means for subtracting the output of the first gain means from the output of the first control means;
The second disturbance compensation means,
Second gain means whose gain coefficient is changed by the gain adjusting means;
A second subtracting means for subtracting the output of the second gain means from the output of the second control means;
The first gain means multiplies the output of the addition means by a gain coefficient and outputs the result to the first subtraction means, and the second gain means multiplies the output of the second disturbance estimation means by a gain coefficient. The image blur correction apparatus according to claim 2 , wherein the image blur correction apparatus outputs the second subtraction means. An optical apparatus, comprising an image shake correction apparatus of any one of claims 1 to 3. An image blur correction device according to any one of claims 1 to 3 ,
An imaging optical system and an imaging device,
An image pickup apparatus, wherein image blur of an image picked up by the image pickup device is corrected by the first optical correction unit and the second optical correction unit . Driving means for performing zoom driving of the imaging optical system;
The imaging apparatus according to claim 5 , further comprising a limiter changing unit that acquires position detection information related to the zoom drive and changes a threshold value of the limiter unit. A control method executed by an image blur correction apparatus that corrects an image blur by a first optical correction unit and a second optical correction unit ,
A calculation step in which a calculation unit calculates a target position of the first optical correction unit and a target position of the second optical correction unit by acquiring a shake detection signal detected by the shake detection unit;
A position detection step of detecting a position of the first optical correction means and a position of the second optical correction means by a position detection means ;
A first control step in which a first control means performs feedback control to converge the position of the first optical correction means to the target position calculated by the calculation means;
A second control step in which a second control unit performs feedback control to converge the position of the second optical correction unit to the target position calculated by the calculation unit;
A first disturbance estimation step in which a first disturbance estimation unit calculates a disturbance to the first optical correction unit;
A second disturbance estimation step in which a second disturbance estimation unit calculates a disturbance to the second optical correction unit;
A first disturbance compensation step in which the first disturbance compensation unit performs disturbance compensation on the first control unit by subtracting the output of the first disturbance estimation unit from the output of the first control unit;
A second disturbance compensation step in which the second disturbance compensation means performs disturbance compensation on the second control means by subtracting the output of the second disturbance estimation means from the output of the second control means;
A limiter means determining the estimation accuracy of the first disturbance estimation means and the estimation accuracy of the second disturbance estimation means;
When the second disturbance estimation means has higher estimation accuracy than the first disturbance estimation means, the lower-order bits below the threshold value determined by the limiter means are applied to the first calculation data by the first disturbance estimation means. Masking means for masking;
And a step of adding a lower bit signal equal to or lower than the threshold in the second calculation data by the second disturbance estimating means to the output of the masking means .

Images