JP2017194529A - Anti-vibration control device - Google Patents

Abstract

An image blur correction process is performed by preventing erroneous detection of camera shake. In a digital camera that executes image blur correction processing, it is determined whether or not the angular velocity is below a reference level A and below a reference level B. In accordance with the magnitudes of the angular velocities with respect to the reference levels A and B, image blur correction for angular blur and rotational blur is set ON / OFF, and image blur correction for parallel blur is set ON / OFF. [Selection] Figure 5

Description

  The present invention relates to an image stabilization control device that suppresses image blur caused by camera shake and the like, and more particularly, to an image blur correction amount calculation process including parallel blur.

  In a digital camera or the like, a camera shake correction device that moves an optical lens or an image sensor along an optical axis orthogonal plane is provided in order to prevent image quality deterioration due to camera shake. Camera shake can be broadly 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 and shift shake) in which the camera moves in the vertical and horizontal directions.

  Under general shooting conditions, for example, shooting conditions with a low shooting magnification at a long distance, the angular blur is dominant, and the influence 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 blurring becomes large. Therefore, parallel blurring is detected along with angular blurring, and these are combined to calculate the image blur correction amount (see, for example, Patent Document 1).

Japanese Patent No. 3513950

  The output of the acceleration sensor is susceptible to environmental changes such as disturbance noise, temperature changes, or gravity changes accompanying posture changes in the hand vibration frequency range. Since the parallel shake amount is obtained by integrating the acceleration output from the acceleration sensor twice, the error amount accompanying the change becomes cumulatively large. For example, in the case of shooting by long-second exposure using a tripod, the cumulative error of parallel blur becomes prominent, and it is difficult to perform high-precision camera shake correction when it shakes due to the influence of wind or the like. In addition, the cumulative error may become remarkable for the gyro sensor.

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

  The anti-vibration control device of the present invention is applicable to optical equipment, electronic equipment, and the like, and includes first shake detection means for detecting angular shake and / or rotational shake of the imaging apparatus, and first detection of parallel shake of the imaging apparatus. And a control unit that drives and controls the image blur correction unit based on the output signal of the first blur detection unit and the output signal of the second blur detection unit, and suppresses the image blur. When the output calculation value of the first blur detection unit is equal to or lower than the first reference level, the control unit does not perform image blur correction for angular blur and / or rotation blur, and the control unit outputs the first blur detection unit. When the calculated value is equal to or lower than a second reference level different from the first reference level, image blur correction for parallel blur is not executed. For example, when the parallel blur is relatively large with respect to cumulative false detection, the second reference level may be set larger than the first reference level.

  The output calculation value here indicates, for example, an output signal itself of a gyro sensor, an angular velocity value obtained by calculation processing, or a position (displacement amount) obtained by integrating the angular velocity value. The first detection means may detect at least one of angular shake and rotational shake. For example, when image blur correction processing is executed in accordance with a predetermined operation of a shooting sequence such as power ON, release button half-press, full press, etc., execution / non-execution determination processing is continuously executed at predetermined time intervals. Execution / non-execution may be determined according to the determination contents.

  On the other hand, an image stabilization control device according to another aspect of the present invention includes a first shake detection unit that detects an angular shake and / or a rotation shake of the imaging device, a second shake detection unit that detects a parallel shake of the imaging device, Image blur correction based on the first output signal corresponding to the angular blur and / or rotational blur output from the first blur detection means and the second output signal corresponding to the parallel blur output from the second blur detection means. A control unit that controls the driving of the unit and suppresses image blur. When the output calculation value of the first blur detection unit is equal to or lower than the first reference period reference level, the control unit is configured to prevent angular blur and / or rotational blur. The image blur correction is performed, and the control unit executes the image blur correction for the parallel blur when the output calculation value of the first blur detection unit is equal to or lower than the second reference period reference level different from the first reference period. . The second reference period can be set longer than the first reference period.

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

It is a block diagram of the digital camera in this embodiment. It is the figure which showed the camera-shake correction apparatus. It is a block diagram of a calculating part. It is a flowchart of an imaging sequence. It is a flowchart which shows the determination process of image blur correction ON / OFF. It is the graph which showed the time-sequential change of angular velocity. 12 is a flowchart illustrating image blur correction ON / OFF determination processing according to the second embodiment. It is the graph which showed the time-sequential change of 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 illustrating a camera shake correction apparatus.

  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 power 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 at the top of the camera, and an image monitor 24 such as an LCD is provided at the back of the camera.

  A system control circuit 40 constituted by a DSP (Digital Signal Processor) or the like is used for a camera such as a shooting operation, an image recording process, and a reproduction display process in accordance with an input operation to an operation member such as a release button or a power button (not shown). Perform overall operation control. A program relating to camera operation control is stored in a memory such as a ROM (not shown).

  When displaying a through image, light from a subject passing through the photographing optical system 31 and the diaphragm 32 forms an image on the light receiving surface of the image sensor 22. The system control circuit 40 performs image signal processing such as white balance adjustment and color conversion processing on the pixel signals for one field or one frame sequentially read from the image sensor 22 to generate color image data. With 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 a half-press operation by a signal from the photographing operation switch 26. Then, AF processing by a contrast method is executed, and the focusing lens group 31C is driven to perform focus adjustment. Further, exposure values such as shutter speed and aperture value are calculated by detecting the brightness of the subject image from the generated image data.

  Further, when the system control circuit 40 detects that the release button is fully pressed by a signal from the photographing operation switch 26, the system control circuit 40 controls the aperture / shutter driving circuit 23 to drive the aperture 32, the shutter 21 and the like based on the calculated exposure value. To do. As a result, an image signal for one frame is read 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, a selected image is read out from a series of recorded images stored in the image memory 25 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-second exposure shooting. When long-second exposure shooting is set, shooting is performed by setting a shutter speed over a long time of several seconds or more during 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 diaphragm 32. When the photographing lens 30 is attached to the camera body 20, the stored data is sent to the system control circuit 40.

  In the camera body 20, an image blur correction device 50 is disposed behind the photographing optical system 31. As shown in FIG. 2, the image blur correction apparatus 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 attached to the circuit board 22b, and the circuit board 22b is attached and fixed to the movable stage 54 so as to be positioned at the center of the opening 54a of the circuit board 22b. An FPC (Flexible Printed Circuits) 55 for driving the image sensor is connected to the back surface of the circuit board 22b.

  On the front surface of the movable stage 54, a pair of drive winding coils (voice coils) C1 and C2 are arranged on the lower side of the image sensor 22 at a predetermined interval, and 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 a drive control FPC 56 that is fixed to the back surface of the movable stage 54, and the movable stage is opened from openings 54b1, 54b2, 54b3, and 54b4 formed in the movable stage 54. 54 is exposed on the front side.

  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. Permanent magnets (not shown) are arranged at positions facing the winding coils C1, C2, C3, and C4 on the back surface (the surface facing the image sensor 22) of the front yoke plate (not shown).

  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. Due to the magnetic interaction between the permanent magnets provided on the front yoke plate and the winding coils C3 and C4, the movable stage 54 moves along the X direction (camera lateral direction). In addition, when a drive current flows through the winding coils C1 and C2, the movable stage 54 similarly moves in the Y direction (camera longitudinal direction) by magnetic interaction.

  The gyro sensor 28 is composed of a plurality of gyro sensors 28 that detect angular shakes of yawing and pitching of the camera 10 and rotational shakes around the optical axis, and the angular velocities around the X, Y, and Z3 axes of the camera body 20 are determined. Detect each. The computing unit 80 calculates an image blur correction amount (displacement amount) due to angular blur and rotational blur based on an 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 a parallel shake occurs in the hand shake. The acceleration sensor 29 is disposed at a location along the optical axis near the back surface of the image sensor 22, for example. However, the acceleration sensor 29 includes an acceleration detection sensor along the X direction (lateral direction of the camera) corresponding to the horizontal direction when the user holds the camera 10 in a normal posture, and the acceleration along the Y direction perpendicular to the sensor. Sensors for detection are provided, and accelerations when the camera 10 is displaced along the X direction and the Y direction are detected. The computing unit 60 calculates an image blur correction amount (displacement amount) due to parallel blur based on an output signal (second output signal) from the acceleration sensor 29.

  The system control circuit 40 calculates an image blur correction amount based on 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 image blur due to camera shake. At this time, the position of the movable stage 54 is feedback-controlled based on signals from the hall sensors H1 to H3.

  The output signal from the acceleration sensor 29 includes a gravitational acceleration component as well as an acceleration component in the direction of parallel shaking caused by hand shake. The calculation unit 60 removes the gravitational acceleration component without using the output signal from the gyro sensor 28 as described below.

  FIG. 3 is a block diagram of the calculation unit 60. Here, the structure of the calculation part with respect to the acceleration sensor output signal according to a Y direction is demonstrated. The same configuration is applied to 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 image blur amount of the translational shake component excluding the gravitational acceleration component is calculated by the integrator 68, HPF 70, and integrator 72. The signal output from the acceleration sensor 29 is branched to the LPF 62 side (hereinafter referred to as sub-side) and the HPF 66 side (hereinafter referred to as main side).

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

  The HPF 64 includes an integrator (not shown), and the values corresponding to the gravitational acceleration components are integrated. When the cut-off frequency fm = 5 Hz, the time constant (= 1 / 2πfm) is approximately 0.03 seconds. In general, since convergence is nearly 100% at 6 times the time constant, convergence takes 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 HPF 66, and the gravitational acceleration component is removed. The signal after removing the gravitational acceleration component corresponds to an acceleration component corresponding to the parallel shake, and is integrated twice by passing through the integrator 68, the HPF 70, and the integrator 72. As a result, the value of the amount of image blur due to camera shake (translational shake) 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 photographing magnification.

  The HPF 66 has the same circuit configuration as that of 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 in the integrator. Since the hand shake frequency is in the range of 1 Hz to 10 Hz and parallel shake components around 1 Hz pass through the HPF 66, the cutoff frequency fn of the HPF 66 is set to be smaller than that of the sub HPF 64.

  With the extremely low cutoff frequency fn of the HPF 66, it takes time until the detection of the parallel shake is effectively performed after the change in the posture of the camera 10, and during that time, the image blur correction cannot be performed effectively. Therefore, the calculation process of the main HPF 66 using the integral value of the sub HPF 64 is performed according to the imaging sequence.

  Specifically, when the power is turned on, internal calculation processing is performed in both the HPF 64 and the HPF 66, and a release button (not shown) is half-pressed or immediately after the power is turned on. Is multiplied by the cut-off frequency ratio fm / fn to the HPF 66 and output as an integral value of the HPF 66. When the release button is fully pressed, the integral value input from the HPF 64 to the HPF 66 is stopped, and the gravitational acceleration component is removed by the operation of the HPF 66.

  In the present embodiment, in order to prevent an increase in the image blur amount error due to disturbance or the like, execution / non-execution of image blur correction for angular blur and rotation blur and execution / non-execution of image blur correction for parallel blur are performed by a gyro. A determination 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 photographing sequence. FIG. 5 is a flowchart showing the image blur correction ON / OFF determination process. FIG. 6 is a graph showing time-series changes in angular velocity.

  When the power is turned on, the image blur correction ON / OFF determination is started (S101). When the release button is pressed halfway, a focusing operation and an 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, image blur correction processing during the exposure period is performed based on the determination result immediately before or when the release is fully pressed. Note that the image blur correction process may be executed in accordance with the release half-press timing, or the image blur correction process may be 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. First, it is determined whether or not the angular velocity detected by the gyro sensor 28 is equal to or lower than a reference level A serving as a threshold (S201). However, the comparison is made based on the angular velocity and the absolute value of the reference level A (first reference level). When the angular velocity is equal to or lower than the reference level A, the image blur correction for angular blur and rotational blur is set to OFF (S203). In the case of the OFF setting, the image blur amount with respect to angular blur and rotational blur is set to zero. On the other hand, if the angular velocity is greater than the reference level A, the image blur correction for angular blur and rotational blur is set to ON (S204).

  Next, it is determined whether the angular velocity is equal to or lower than a reference level B (second reference level) (S204). The second reference level B has a larger absolute value than the reference level A. If the angular velocity is below the reference level, image blur correction for parallel blur is set to OFF (S206). On the other hand, if the angular velocity exceeds the reference level, image blur correction for parallel blur is set to ON (S205).

  Accordingly, when the angular velocity is equal to or lower than the reference level A, both the image blur correction for the angular blur and the rotation blur and the image blur correction for the parallel blur are both set to OFF. When the angular velocity exceeds the reference level A but is below the reference level B, image blur correction for angular blur and rotational blur is set to ON, while image blur correction for parallel blur is set to OFF. When the angular velocity exceeds the reference level B, both image blur correction for angular blur and rotational blur and image blur correction for parallel blur are both set to ON.

  Here, the determination processing 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 sensor of two or three axes, Handle multiple times. For example, the output signals are added up by multiplying the gyro sensor output value of each axis by the weighting coefficient and adding the weighting coefficient.

  FIG. 6 shows a time-series change in angular velocity detected at predetermined time intervals after the power is turned on. A period in which the angular velocity is between the reference level A and the reference level B is represented by T1, and a period below the reference level A is represented by T2. When the release full press timing occurs in the period T1 as shown in FIG. 6, the image blur correction for parallel blur is set to OFF.

  For example, while using a tripod and increasing the shooting magnification to perform long-second exposure shooting, the camera 10 may shake lightly due to the influence of wind. At this time, the image blur correction of parallel blur that increases the cumulative detection error is not executed. On the other hand, the image blur correction with respect to the shaking of the camera 10 can be performed by executing the image blur correction with respect to the angle and the rotation blur.

  Further, when the user holds the camera and shoots the image, the angular velocity exceeds the reference level B, so that the image blur correction process can be appropriately executed for angular blur, rotational blur, and parallel blur. The sizes of the reference levels A and B may be determined in consideration of the force applied to the camera due to disturbance such as wind, the amount of detection error, the angular velocity range when the camera shakes while being held by hand.

  The image blur correction ON / OFF determination process shown in FIG. 5 ends in response to the release button being fully pressed (S106). Then, depending on the determination result, execution of image blur correction for angular blur and rotational blur starts or is not performed (S107, S108). Similarly, execution of image blur correction for parallel blur is started or not executed based on the determination result (S109, S110). When the exposure period has elapsed, the execution of the image blur correction process ends (S111 to S113). Note that the determination process may be performed immediately after the power supply is being displayed during live view display, or the determination process may be performed in response to a release half-press operation, and image blur correction ON / OFF may be set based on the determination result.

  As described above, according to the present embodiment, in the digital camera 10 that executes the image blur correction process, it is determined whether or not the angular velocity is the reference level A or less and the reference level B or less. In accordance with the magnitudes of the angular velocities with respect to the reference levels A and B, image blur correction for angular blur and rotational blur is set ON / OFF, and image blur correction for parallel blur is set ON / OFF.

  Instead of determining whether or not to perform image blur correction using the angular velocity, the output itself of the gyro sensor, the filtered one, the integrated value, that is, the position (displacement), or the like may be used as a determination material. Further, the reference level A may be made larger than the reference level B, and the reference level may be switched. For example, the present invention can be applied to a camera or the like in which the amount of detection error is more noticeable in angular blur and rotational blur than in parallel blur due to problems such as accuracy of the reference level gyro sensor.

  Next, a digital camera according to the second embodiment will be described with reference to FIGS. In the second embodiment, the image blur correction ON / OFF is determined based on the length of the duration in which the angular velocity is equal to or lower than the reference level.

  FIG. 7 is a flowchart showing image blur correction ON / OFF determination processing according to the second embodiment. FIG. 8 is a graph showing time-series changes in angular velocity.

  In step S301, it is determined whether or not the angular velocity is equal to or lower than the reference level M, and a period during which the angular velocity is equal to or lower than the reference level M, that is, a period until the angular velocity exceeds the reference level M is counted. When the period that is equal to or less than the reference level M is equal to or less than the first reference period J1 that is a threshold value, the image blur correction for angular blur and rotational blur is set to ON. When the reference period J1 is exceeded, image blur correction for angular blur and rotational blur is set to OFF (S302, S303).

  In step S304, it is determined whether or not the period below the reference level M is less than or equal to the second reference period J2. When the period below the reference level M is the second reference period J2 or less, the image blur correction for parallel blur is set to ON, and when the period below the reference level M exceeds the second reference period J2, the parallel blur is corrected. Image blur correction is set to OFF (S305, S306). In addition, as the angular velocity once exceeds the reference level M and then becomes the reference level M or less again, the period of the reference level M or less is started again.

  In FIG. 8, periods below the reference level M are indicated by T3 and T4. In the period T3, in the section X1 from the elapse of the first reference period J1 until the period J2 is reached, the period of the reference level M or less exceeds the first reference period J1, while the second reference period J2 or less. It becomes. Therefore, image blur correction for angular blur and rotational blur is set to OFF (S303), while image blur correction for parallel blur is set to ON (S305).

  On the other hand, in the period T4, the section X2 after the second reference period J2 is a period exceeding the first and second reference periods J1 and J2. Therefore, when the release button full press timing is performed at the timing shown in FIG. 5, image blur correction for angular blur, rotational blur, and parallel blur is all set to OFF.

  In this way, by setting the image blur correction ON / OFF based on how long the period during which the image blur amount is equal to or less than the reference level M has been set, the detection error amount can be suppressed in both tripod shooting and handheld shooting. Image blur correction processing can be executed. For example, even if hand shake is suppressed for a moment in hand-held shooting, image blur correction is not set to OFF. On the other hand, in tripod photography, it is possible to deal with camera movements that do not involve angular blur such as framing parallelism. As in the first embodiment, when the misdetection amount of the gyro sensor that detects angular shake and rotational shake is relatively large, the sizes of the first reference periods J1 and J2 may be switched. The first reference periods J1 and J2 may be determined by comparing changes in shake signals detected during handheld shooting and tripod shooting.

10 Digital camera (imaging device)
20 Camera body 28 Gyro sensor (first shake detection means)
29 Acceleration sensor (second shake detection means)
30 Photography lens (optical equipment)
40 System control circuit (control unit)
50 Image blur correction device (image blur correction means)

Claims (6)

First blur detection means for detecting angular blur and / or rotational blur of the imaging device;
Second shake detection means for detecting parallel shake of the imaging device;
A control unit that controls driving of the image blur correction unit based on the output signal of the first blur detection unit and the output signal of the second blur detection unit and suppresses the image blur;
When the output calculation value of the first shake detection unit is equal to or lower than the first reference level, the control unit does not perform image blur correction for angular shake and / or rotational shake,
The image stabilization control apparatus, wherein the control unit does not perform image blur correction for parallel blur when an output calculation value of the first blur detection unit is equal to or lower than a second reference level different from the first reference level. First blur detection means for detecting angular blur and / or rotational blur of the imaging device;
Second shake detection means for detecting parallel shake of the imaging device;
The image is based on a first output signal corresponding to the angular blur and / or rotational blur output from the first blur detection unit and a second output signal corresponding to the parallel blur output from the second blur detection unit. A control unit that controls driving of the blur correction unit and suppresses image blur,
The controller performs image blur correction for angular blur and / or rotational blur when an output calculation value of the first blur detection unit is equal to or lower than a first reference period reference level;
The control unit executes image blur correction for parallel blurring when an output calculation value of the first blur detection unit is equal to or lower than a second reference period reference level different from the first reference period. Anti-vibration control device.   The image stabilization control device according to claim 1, wherein the second reference level is higher than the first reference level.   The anti-vibration control device according to claim 2, wherein the second reference period is longer than the first reference period.   5. The image stabilization control device according to claim 1, wherein the output calculation value is an angular velocity or a position.   An optical apparatus comprising the image stabilization control device according to claim 1.

Images