JP6862675B2 - Anti-vibration control device - Google Patents

Description

The present invention relates to an anti-vibration control device that suppresses image blurring caused by camera shake and the like, and more particularly to a calculation process of an image blurring amount.

In digital cameras and the like, in order to prevent deterioration of image quality due to camera shake, a camera shake correction device for moving an optical lens or an image sensor along an orthogonal plane of the optical axis is provided. Camera shake is roughly classified into angular shake such as yawing and pitching, rotational shake around the center of the optical axis, and parallel shake (also called translational shake or shift shake) in which the camera moves in the vertical and horizontal directions.

Under general shooting conditions, for example, shooting conditions at a long distance and a low shooting magnification, angular blur is dominant, and the effect of image blur due to parallel blur is small. However, under shooting conditions (macro shooting) with a high shooting magnification at a close distance, the influence of parallel blur becomes large. Therefore, parallel blurring is detected together with angular blurring, and the amount of image blurring is calculated by combining these (see, for example, Patent Document 1).

Japanese Patent No. 3513950

The output of the accelerometer is susceptible to environmental changes such as disturbance noise, temperature changes, and gravity changes due to attitude changes in the camera shake frequency range. Since the amount of parallel blur is obtained by integrating the acceleration output from the acceleration sensor twice, the amount of error due to the change becomes cumulatively large. For example, in the case of shooting with a long exposure using a tripod, the cumulative error of parallel blur becomes remarkable, and it is difficult to perform highly accurate image stabilization when the camera shakes due to the influence of wind or the like. In addition, the cumulative error of the gyro sensor may become significant.

Therefore, even if the detection of parallel blur, angular blur, or rotational blur is affected by environmental changes or the like, it is required to appropriately calculate the image blur amount and perform camera shake correction with high accuracy.

The anti-vibration control device of the present invention can be applied to an optical device, an electronic device, or the like, and is a first blur that detects at least one of an angular blur and a rotational blur (hereinafter referred to as an angular blur and / or a rotational blur) of the imaging device. The image blur correction means is driven and controlled based on the detection means, the second blur detection means for detecting the parallel blur of the imaging device, the output signal of the first blur detection means, and the output signal of the second blur detection means, and the image is imaged. When the control unit is provided with a control unit that suppresses blurring and the output calculation value of the first blur detection means continues to be equal to or lower than the first reference level for a predetermined period, the output calculation value of the first blur detection means is the first reference. While the second reference level different from the level is not exceeded, the correction effect of the image blur correction processing for at least one of the angular blur and / or the rotational blur and the parallel blur is suppressed. In order to suppress the image blur correction effect, for example, the second reference level can be made larger than the first reference level.

For example, when the output calculation value of the first blur detection means continues to be equal to or lower than the first reference level for a predetermined period, the control unit performs image blur correction processing for angular blur and / or rotational blur and image blur correction processing for parallel blur. You don't have to do at least one of them. When executing image blur correction processing according to a predetermined operation of the shooting sequence such as turning on the power, pressing the release button halfway, or pressing the release button fully, the execution / non-execution judgment processing is continuously executed at predetermined time intervals, and the judgment content at the time of the predetermined operation Execution / non-execution can be determined according to.

Further, when the output calculation value of the first blur detecting means continues to be equal to or lower than the first reference level for a predetermined period, the control unit receives the output signal from the first blur detecting means and the output signal from the second blur detecting means. It is also possible to multiply the image blur amount calculated from at least one of the output signals by a coefficient smaller than 1. Alternatively, when the second blur detecting means is provided with a digital filter that suppresses the amount of image blur calculated based on the output signal from the second blur detecting means, the control unit performs the output calculation value of the first blur detecting means. When the state of is below the first reference level continues for a predetermined period, the digital filter function can be set to ON.

As described above, according to the present invention, it is possible to prevent erroneous detection of camera shake under various shooting conditions and execute appropriate image blur correction processing.

It is a block diagram of the digital camera in this embodiment. It is a figure which showed the camera shake correction device. It is a block diagram of an arithmetic unit. It is a flowchart of a shooting sequence. It is a flowchart which shows the determination process of image blur correction ON / OFF. , It is a graph showing the time-series change of the angular velocity.

Hereinafter, the present embodiment will be described with reference to the drawings.

FIG. 1 is a block diagram of a digital camera according to the first embodiment. FIG. 2 is a diagram showing a camera shake correction device.

The digital camera 10 includes a camera body 20 and a photographing lens 30 that is detachably attached to the camera body 20, and the photographing lens 30 includes a fixed lens group 31A, a variable magnification lens group 31B, and a focusing lens group 31C. A photographing optical system 31 composed of a plurality of lens groups is housed. A release button (not shown) is provided on the upper part of the camera, and an image monitor 24 such as an LCD is installed on the back side of the camera.

The system control circuit 40 composed of a DSP (Digital Signal Processor) or the like is a camera such as a shooting operation, an image recording process, a playback display process, etc., in response to an input operation to an operation member such as a release button or a power button (not shown). Controls the overall operation. A program related to camera operation control is stored in a memory such as a ROM (not shown).

When displaying a through image, the light from the subject that has passed through the photographing optical system 31 and the aperture 32 is imaged on the light receiving surface of the image sensor 22. The system control circuit 40 generates color image data by performing image signal processing such as white balance adjustment and color conversion processing on pixel signals for one field or one frame sequentially read from the image sensor 22. Based on the generated image data, a real-time moving image is displayed on the image monitor 24 as a through image.

When the release button is half-pressed, the system control circuit 40 detects the half-pressed operation by a signal from the photographing operation switch 26. Then, AF processing by the contrast method is executed, and the focusing lens group 31C is driven to adjust the focus. Further, by detecting the brightness of the subject image from the generated image data, the exposure values such as the shutter speed and the aperture value are calculated.

Further, the system control circuit 40 controls the aperture / shutter drive circuit 23 when detecting the full press of the release button by the signal from the shooting operation switch 26, and drives the aperture 32, the shutter 21, etc. based on the calculated exposure value. To do. As a result, the image signal for one frame is read out from the image sensor 22.

The system control circuit 40 generates still image data based on the read pixel signal for one frame. The generated still image data is recorded in the image memory 25. When the reproduction mode is set, the selected image from the series of recorded images stored in the image memory 25 is read out and reproduced and displayed on the image monitor 24.

The user can select the shooting content on the menu screen, and can set, for example, bracket shooting or long-exposure shooting. When long-exposure shooting is set, the shutter speed is set for a long time of several seconds or longer at the time of shooting to perform shooting.

The photographing lens 30 includes a communication memory 33 that stores lens information data such as the resolving power of the photographing optical system 31 and the aperture diameter of the aperture 32. When the photographing lens 30 is attached to the camera body 20, the stored data is sent to the system control circuit 40.

An image blur correction device 50 is arranged behind the photographing optical system 31 in the camera body 20. As shown in FIG. 2, the image blur correction device 50 includes a movable stage 54 that can move along a plane perpendicular to the optical axis with respect to the fixed support substrate. However, FIG. 2 is a view of the movable stage 54 as viewed from the front (photographing lens side).

The back surface of the image sensor 22 is mounted on the circuit board 22b, and the circuit board 22b is mounted and fixed to the movable stage 54 so as to be located at the center of the opening 54a of the circuit board 22b. An image sensor driving FPC (Flexible Printed Circuits) 55 is connected to the back surface of the circuit board 22b.

A pair of drive winding coils (voice coils) C1 and C2 are arranged on the front surface of the movable stage 54 at predetermined intervals on the lower side of the image sensor 22, and are arranged on both the left and right sides of the image sensor 22. A pair of drive winding coils C3 and C4 are arranged. The winding coils C1, C2, C3, and C4 are mounted on the drive control FPC 56 fixed to the back surface of the movable stage 54, and the movable stage is formed from the openings 54b1, 54b2, 54b3, 54b4 formed in the movable stage 54. It is exposed on the front side of 54.

Hall sensors H1, H2, and H3 are mounted at substantially the center of the winding coils C1, C2, and C3 mounted on the drive control FPC 56. Permanent magnets (not shown) are arranged on the back surface (the surface facing the image sensor 22) of the front yoke plate (not shown) at positions facing the winding coils C1, C2, C3, and C4.

When a drive current flows through the winding coils C3 and C4, the winding coils C3 and C4 function as electromagnets, and a magnetic field change occurs in the vicinity of the coils. The movable stage 54 moves along the X direction (lateral direction of the camera) due to the magnetic interaction between the permanent magnets provided on the front yoke plate and the winding coils C3 and C4. Further, when a drive current flows through the winding coils C1 and C2, the movable stage 54 moves in the Y direction (camera vertical direction) due to magnetic interaction in the same manner.

The gyro sensor 28 is composed of a plurality of gyro sensors 28 that detect yawing and pitching angular sway of the camera 10 and rotational sway around the optical axis, and determines the angular velocity of the camera body 20 around the X, Y, and Z3 axes. Detect each. The calculation unit 80 calculates an image blur correction amount (displacement amount) due to angular blur and rotational blur based on the output signal (first output signal) from the gyro sensor 28. However, the image blur correction amount is obtained for each component in the X direction and the Y direction.

On the other hand, the acceleration sensor 29 detects the acceleration when parallel shake occurs in the camera shake. The acceleration sensor 29 is arranged at a location along the optical axis near the back surface of the image sensor 22, for example. However, the acceleration sensor 29 includes a sensor for detecting acceleration along the X direction (lateral direction of the camera) corresponding to the horizontal direction when the user holds the camera 10 in the normal posture, and acceleration along the Y direction perpendicular to the sensor. Each of the detection sensors is provided, and the acceleration when the camera 10 is displaced along the X direction and the Y direction is detected, respectively. The calculation unit 60 calculates the image blur correction amount (displacement amount) due to parallel blurring based on the output signal (second output signal) from the acceleration sensor 29.

The system control circuit 40 calculates the image blur correction amount based on the output signals from the gyro sensor 28 and the acceleration sensor 29. Then, a drive signal is output to the moving member drive circuit 59, and the movable stage 54 is moved along the XY plane so as to cancel the image blur caused by camera shake. At this time, the position of the movable stage 54 is feedback-controlled based on the signals from the hall sensors H1 to H3.

The output signal from the acceleration sensor 29 includes not only the acceleration component in the parallel blur direction caused by camera shake but also the gravitational acceleration component. As described below, the calculation unit 60 removes the gravitational acceleration component without using the output signal from the gyro sensor 28.

FIG. 3 is a block diagram of the calculation unit 60. Here, the configuration of the calculation unit for the acceleration sensor output signal according to the Y direction will be described. The same configuration is used for the acceleration sensor output signal corresponding to the X direction.

The calculation unit 60 includes a low-pass filter (LPF) 62 and a high-pass filter (HPF) 64, and further includes an HPF 66, an integrator 68, an HPF 70, and an integrator 72. The HPFs 64 and 66 have a function of removing the gravitational acceleration component, and the integrators 68, HPF70, and the integrator 72 calculate the amount of image blurring of the translational deflection component excluding the gravitational acceleration component. The signal output from the acceleration sensor 29 is branched into the LPF62 side (hereinafter referred to as the sub side) and the HPF66 side (hereinafter referred to as the main side).

On the sub side of the calculation unit 60, after the high frequency noise is removed by the LPF 62, the gravitational acceleration component is removed by the HPF 64. The gravitational acceleration (= 9.8 m / s ² ) is a constant value, and its frequency can be regarded as extremely small. The HPF64 has a function of accurately removing the gravitational acceleration component in a short time, and here, the cutoff frequency fm of the HPF64 is set to a relatively large 5 Hz.

The HPF64 includes an integrator (not shown), and a value corresponding to the gravitational acceleration component is integrated. When the cutoff frequency fm = 5 Hz, the time constant (= 1 / 2πfm) is about 0.03 seconds. Generally, it converges to nearly 100% at 6 times the time constant, so it converges in about 0.18 seconds.

On the other hand, the output signal from the acceleration sensor 29 sent to the main side is input to the HPF66, and the gravitational acceleration component is removed. The signal after removing the gravitational acceleration component corresponds to the acceleration component corresponding to the parallel runout, and is integrated twice by passing through the integrator 68, the HPF 70, and the integrator 72. As a result, the value of the image blur amount due to camera shake (translational runout) is input to the system control circuit 40. In the system control circuit 40, the amount of image blur due to translational shake is corrected according to the shooting magnification.

The HPF 66 has the same circuit configuration as the HPF 64, and when an output signal from the acceleration sensor 29 is input, a value corresponding to the gravitational acceleration component is integrated into the integrator. Since the camera shake frequency is in the range of 1 Hz to 10 Hz and the parallel runout component around 1 Hz also passes through the HPF66, the cutoff frequency fn of the HPF66 is set smaller than that of the HPF64 on the sub side.

At the very small cutoff frequency fn of the HPF66, it takes time from the change in the attitude of the camera 10 to the effective detection of the parallel runout, and the image blur correction cannot be effectively performed during that time. Therefore, the arithmetic processing of the HPF66 on the main side using the integrated value of the HPF64 on the sub side is performed according to the shooting sequence.

Specifically, when the power is turned on, internal arithmetic processing is performed on both HPF64 and HPF66, and the release button (not shown) is half-pressed, or immediately after the power is turned on, the integrated value of HPF64 on the sub side. Is multiplied by the cutoff frequency ratio fm / fn, the value is input to the HPF66, and the value is output as the integrated value of the HPF66. When the release button is fully pressed, the input of the integrated value from the HPF64 to the HPF66 is stopped, and the gravitational acceleration component is removed by the operation of the HPF66.

In the present embodiment, in order to prevent the error in the amount of image blur from increasing due to disturbance or the like, execution / non-execution of image blur correction for angular blur and rotational blur and execution / non-execution of image blur correction for parallel blur are performed by the gyro. Judgment is made based on the output signal from the sensor 28. This will be described in detail below.

FIG. 4 is a flowchart of the shooting sequence. FIG. 5 is a flowchart showing a determination process of image blur correction ON / OFF.

When the power is turned on, the image blur correction ON / OFF determination process is started (S101). Then, when the release button is pressed halfway, the focusing operation and the exposure calculation process are executed. When the release button is fully pressed, the image blur correction ON / OFF determination process ends (S101 to S106). Therefore, the image blur correction process during the exposure period is performed based on the determination result when the release is fully pressed or immediately before the release. The image blur correction process may be executed in accordance with the release half-press timing, or the image blur correction process may be continuously executed immediately after the power is turned on.

The image blur correction ON / OFF determination process shown in FIG. 5 is executed at predetermined time intervals. In step S201, it is determined whether or not the flag representing the correction effect when the image blur correction is executed is "F2". In the present embodiment, the threshold value, which is the execution determination criterion of the image blur correction processing performed during the exposure period, is switched according to the output change of the output signal. Here, the process of comparing the magnitude of the relatively low threshold value and the angular velocity is represented by the flag "F1", and the process of comparing the relatively high threshold value and the angular velocity is represented by the flag "F2".

If it is determined in step S201 that the flag is set to "F1" instead of "F2", the process proceeds to step S206. In step S206, it is determined whether or not the angular velocity is equal to or lower than the first reference level L1. However, the magnitude of the absolute value of the angular velocity and the absolute value of the first reference level L1 are compared. When the angular velocity is the first reference level L1 or less, the image blur correction process is set to OFF (S207), and it is determined whether or not the state of the first reference level L1 or less continues for a certain period of time A or more (S208). .. At the start of determination, the flag is initially set to "F1".

FIG. 6 is a graph showing the time-series changes in the angular velocity. In the case of tripod photography, no camera shake has occurred and the detected angular velocity is within a relatively small value. Therefore, when the state in which the output signal level from the gyro sensor 28 is low has passed for a certain period of time A, it can be considered that tripod photography is being performed. The first reference level L1 that serves as A and the threshold value for a certain period of time can be determined by measuring the output signal level from the gyro sensor 28 when the tripod is photographed in advance.

In step S208, when it is determined that the state in which the angular velocity is equal to or lower than the first reference level L1 continues for a certain period of time A or more, the flag is set to "F2" (S209). When the flag F2 is set, in the next routine, it is determined whether or not the angular velocity is equal to or lower than the second reference level L2 (S201, S202).

As shown in FIG. 6, the second reference level L2 has a larger absolute value than the first reference level L1. If the rear angular velocity with the flag set to "F2" does not exceed the second reference level L2, the image blur correction process is set to OFF (S203). Therefore, when the release button is fully pressed at the timing shown in FIG. 6, the image blur correction process is not executed during the exposure period.

On the other hand, in step S202, when it is determined that the angular velocity exceeds the second reference level L2, the flag is switched from "F2" to "F1", and the image blur correction process is set to ON. (S203, S204). Such a determination process is continued until the release button is fully pressed (steps S101 to S106 in FIG. 4).

Here, the determination process is performed based on the output from the gyro sensor of one of the X, Y, and Z axes, but when using the output signals of the gyro sensors of two or three axes, they are used. Handle in a complex manner. For example, the weighting coefficient is multiplied by the output value of the gyro sensor of each axis and added to add up the output signals.

As described above, according to the present embodiment, in the digital camera 10 provided with the image blur correction device 50 that performs the image blur correction processing for angular blur and rotational blur and the image blur correction processing for parallel blur, the output signal from the gyro sensor 28. If the angular velocity detected from is equal to or less than the first reference level L1 and the state continues for the period A, and if the angular velocity is equal to or less than the second reference level L2 larger than the first reference level L1, then in the subsequent section X. Set the image blur correction processing setting to OFF.

In tripod shooting with a high shooting magnification, even if the camera shakes lightly due to the influence of the wind, we want to suppress the image blur correction effect for parallel blurring, which increases the cumulative detection error. Considering that image blurring hardly occurs in tripod shooting if there is no wind, by judging it as tripod shooting, even if the camera is shaken by the wind after that, it will be regarded as a momentary and exceptional image blur correction. Do not execute the process. According to FIG. 6, in the section X after the period A, as long as the angular velocity is equal to or less than the second reference level L2, the image blur correction process is set to OFF and the image blur correction process is not performed. As a result, it is possible to prevent the execution of the image blur correction process due to the erroneous detection of parallel blur. On the other hand, in the case of handheld shooting, it is difficult to fall below the first reference level L1 for a certain period of time, and even if the user happens to hold the camera so as not to cause camera shake for a certain period of time, the angular velocity remains at the second reference level L2. When a camera shake that exceeds the camera shake occurs, the image blur can be effectively suppressed by switching from the flag F2 to the flag F1.

In the present embodiment, the image blur correction process for angular blur and rotational blur and the image blur correction process for parallel blur are set to ON / OFF at the same time, but the determination may be performed separately. It is also possible to determine ON / OFF only for either the image blur correction process for angular blur and rotational blur or the image blur correction process for parallel blur. For example, when the cumulative detection error of the amount of image blur due to parallel blur is large, only the image blur correction process for parallel blur may be set ON / OFF.

Further, instead of setting ON / OFF for the image blur correction process, the image blur correction effect may be suppressed by multiplying the control target value (image blur amount) by a coefficient (<1). Alternatively, a digital filter for reducing the calculated image blur amount may be provided, and the digital filter function may be turned on when the conditions are satisfied.

The magnitude of the first reference level L1 and the second reference level L2 may be exchanged. Further, the image blur correction effect is not suppressed even when the angular velocity is equal to or lower than the first reference level A, and the image blur correction effect is suppressed only after the period A is elapsed when the angular velocity is equal to or lower than the first reference level A. You may try to do it. Further, it is also possible to perform the determination process based on the position (displacement amount) instead of the angular velocity of the gyro sensor, and the calculated value of the output signal from the gyro sensor may be used.

10 Digital camera (imaging device)
20 Camera body 28 Gyro sensor (1st blur detection means)
29 Accelerometer (second blur detection means)
30 Shooting lens (optical equipment)
40 System control circuit (control unit)
50 Image blur correction device (image blur correction means)

Claims (7)

The first blur detecting means for detecting the angular blur and / or the rotational blur of the image pickup apparatus, and
A second blur detection means for detecting parallel blur of the image pickup device, and
A control unit that drives and controls the image blur correction means based on the output signal of the first blur detecting means and the output signal of the second blur detecting means and suppresses the image blur is provided.
When the control unit continues the state in which the output calculation value of the first blur detection means is equal to or lower than the first reference level for a predetermined period, the output calculation value of the first blur detection means is the first reference after the predetermined period. An anti-vibration control device characterized by suppressing the correction effect of image blur correction processing for at least one of angular blur and / or rotational blur and parallel blur as long as the second reference level different from the level is not exceeded. When the control unit continues the state in which the output calculation value of the first blur detection means is equal to or lower than the first reference level for a predetermined period, image blur correction processing and parallel for angular blur and / or rotational blur are performed after the predetermined period. The anti-vibration control device according to claim 1, wherein at least one of the image blur correction processes for blurring is not executed. When the control unit continues the state in which the output calculation value of the first blur detecting means is equal to or lower than the first reference level for a predetermined period, the output signal from the first blur detecting means and the second blur are detected after the predetermined period. The anti-vibration control device according to claim 1, wherein the image blur amount calculated from at least one of the output signals from the detection means is multiplied by a coefficient smaller than 1. The second blur detecting means further includes a digital filter that suppresses an image blur amount calculated based on an output signal from the second blur detecting means.
A claim characterized in that, when the control unit continues the state in which the output calculation value of the first blur detection means is equal to or lower than the first reference level for a predetermined period, the digital filter function is set to ON after the predetermined period. Item 2. The anti-vibration control device according to item 1. The anti-vibration control device according to any one of claims 1 to 4, wherein the second reference level is larger than the first reference level. The anti-vibration control device according to any one of claims 1 to 5, wherein the output calculation value of the first blur detection means is an angular velocity or a position. An optical device provided with the anti-vibration control device according to any one of claims 1 to 6.

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