JP2017194530A - Vibration proof control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration proof control device that executes appropriate image shake correction processing by preventing wrong detection of camera shake.SOLUTION: A digital camera includes an image shake correction device performing image shake correction processing to correct angular shake and rotational shake and image shake correction processing to correct parallel shake. When the angular velocity detected from an output signal from a gyro sensor is equal to or less than a first reference level L1 and the state continues for a period A, if the angular velocity is equal to or less than a second reference level L2 larger than the first reference level L1, the digital camera turns off the image shake correction processing in a subsequent section X.SELECTED DRAWING: Figure 6

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 amount calculation process.

  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 blur is detected together with angular blur, and these are combined to calculate the amount of image blur (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 remarkable, and when it shakes due to the influence of wind or the like, it is difficult to perform high-precision camera shake correction. 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 is a first shake that detects at least one of angular shake and rotational shake (hereinafter referred to as angular shake and / or rotational shake) of the imaging apparatus. Based on the detection means, the second shake detection means for detecting the parallel shake of the imaging device, the output signal of the first shake detection means, and the output signal of the second shake detection means, the image blur correction means is driven and controlled. A control unit that suppresses blurring, and the control unit determines that the output calculation value of the first shake detection unit is the first reference when the output calculation value of the first shake detection unit continues for a predetermined period of time. While the second reference level different from the level is not exceeded, the correction effect of the image blur correction process on at least one of angular blur and / or rotational blur and 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 unit is 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. At least one of them should not be executed. When image blur correction processing is executed in accordance with a predetermined operation of the shooting sequence, such as when the power is turned on, the release button is pressed halfway or fully pressed, execution / non-execution determination processing continues to be executed at predetermined time intervals. Execution / non-execution can be determined according to

  In addition, when the state where the output calculation value of the first shake detection unit is equal to or lower than the first reference level continues for a predetermined period, the control unit outputs the output signal from the first shake detection unit and the output signal from the second shake detection unit. The image blur amount calculated from at least one of the output signals can be multiplied by a coefficient smaller than 1. Alternatively, when the second shake detection unit is provided with a digital filter that suppresses the image blur amount calculated based on the output signal from the second shake detection unit, the control unit outputs the output calculation value of the first shake detection unit. When the state 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 with respect to various shooting conditions 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.

  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.

  When the power is turned on, an image blur correction ON / OFF determination process 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. In step S201, it is determined whether or not the flag indicating the correction effect at the time of executing the image blur correction is “F2”. In the present embodiment, a threshold value that is an execution determination criterion for image blur correction processing performed during the exposure period is switched in accordance with the output change of the output signal. Here, the process of comparing the relatively low threshold value with the angular velocity is represented by a flag “F1”, and the process of comparing the relatively high threshold value with the angular velocity is referred to as a 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 absolute value of the angular velocity is compared with the magnitude of the absolute value of the first reference level L1. When the angular velocity is equal to or lower than the first reference level L1, the image blur correction process is set to OFF (S207), and it is determined whether or not the state equal to or lower than the first reference level L1 continues for a certain period A or more (S208). . Note that the flag is initially set to “F1” at the start of determination.

  FIG. 6 is a graph showing time-series changes in angular velocity. In the case of tripod photography, camera shake does not occur, and the detected angular velocity is within a relatively small value. Accordingly, when the state in which the output signal level from the gyro sensor 28 is at a low level has passed for a certain period of time A, it can be considered that the tripod shooting is being performed. The first reference level L1 serving as the fixed period A and the threshold value can be determined by measuring the output signal level from the gyro sensor 28 when the tripod is photographed in advance.

  If it is determined in step S208 that the state where the angular velocity is equal to or lower than the first reference level L1 continues for a certain period A or longer, the flag is set to “F2” (S209). When the flag F2 is set, in the next routine, it is determined whether the angular velocity is equal to or lower than the second reference level L2 (S201, S202).

  As shown in FIG. 6, the absolute value of the second reference level L2 is larger than that of the first reference level L1. If the rear angular velocity at which the flag is 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, when it is determined in step S202 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 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.

  As described above, according to the present embodiment, in the digital camera 10 including the image blur correction apparatus 50 that performs the image blur correction process for the angular blur and the rotation blur and the image blur correction process for the parallel blur, the output signal from the gyro sensor 28. When the angular velocity detected from the first reference level L1 is equal to or lower than the first reference level L1 and the state continues for the period A, if the angular velocity is equal to or lower than the second reference level L2 larger than the first reference level L1, Set the image blur correction processing setting to OFF.

  When using a tripod with a high 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 blur that causes a large cumulative detection error. In tripod photography, considering that there is almost no image blur if there is no wind, it is judged as tripod photography, and even if the camera is shaken by the wind thereafter, it is regarded as an instantaneous 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 lower 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 execution of image blur correction processing due to erroneous detection of parallel blur. On the other hand, in the case of hand-held shooting, it is difficult to fall below the first reference level L1 for a certain period, and even if the user holds the camera so that it does not shake for a certain period of time, the angular velocity does not exceed the second reference level L2. When a camera shake exceeding the above value 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 the angular blur and the rotation blur and the image blur correction process for the parallel blur are set to ON / OFF at the same time. However, the determination may be performed separately. It is also possible to make ON / OFF determination for only one of image blur correction processing for angular blur and rotational blur or image blur correction processing for parallel blur. For example, when the cumulative detection error of the image blur amount due to the parallel blur is large, only the image blur correction process for the parallel blur may be set ON / OFF.

  Further, the image blur correction effect may be suppressed by multiplying the control target value (image blur amount) by a coefficient (<1) instead of the ON / OFF setting of the image blur correction process. 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 condition is satisfied.

  The first reference level L1 and the second reference level L2 may be interchanged. In addition, 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 when the angular velocity is equal to or lower than the first reference level A. You may make it do. Furthermore, determination processing can be performed based on the position (displacement amount) instead of the angular velocity of the gyro sensor, and an arithmetic value of an output signal from the gyro sensor may be used.

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 (7)

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 control unit determines that the output calculation value of the first shake detection means is below the first reference level for a predetermined period, the output calculation value of the first shake detection means is different from the first reference level. An image stabilization control device that suppresses a correction effect of image blur correction processing on at least one of angle blur and / or rotation blur and parallel blur while not exceeding a level.   When the control unit outputs a value that is less than or equal to the first reference level for a predetermined period, the image blur correction process for angular blur and / or rotational blur and the image blur correction process for parallel blur are performed. The image stabilization control device according to claim 1, wherein at least one of them is not executed.   When the control unit is in a state where the output calculation value of the first shake detection means is below the first reference level for a predetermined period, the output signal from the first shake detection means and the output signal from the second shake detection means The image stabilization control apparatus according to claim 1, wherein an image blur amount calculated from at least one of the output signals is multiplied by a coefficient smaller than one. The second blur detection unit further includes a digital filter that suppresses an image blur amount calculated based on an output signal from the second blur detection unit;
2. The prevention according to claim 1, wherein the control unit sets the digital filter function to ON when a state where an output calculation value of the first shake detection unit is equal to or lower than a first reference level continues for a predetermined period. Vibration control device.   5. The image stabilization control device according to claim 1, wherein the second reference level is higher than the first reference level.   6. The image stabilization control apparatus according to claim 1, wherein an output calculation value of the first shake detection unit is an angular velocity or a position.   An optical apparatus comprising the image stabilization control device according to claim 1.

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