JP2015152886A - Imaging device and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device that can perform accurate image shake correction even when acceleration is applied to angular velocity detection means.SOLUTION: There is provided an imaging device including a shake detection part that detects angular velocity indicating the shake applied to the device. The imaging device detects acceleration applied to an angular velocity sensor 201, which is the shake detection part, and corrects the angular velocity on the basis of the detected acceleration. The imaging device drives an IS unit 103 to correct image shake on the basis of the corrected angular velocity.

Description

  The present invention relates to an imaging apparatus and a control method thereof.

  2. Description of the Related Art Conventionally, in an imaging apparatus having a function of correcting image shake due to typical camera shake, a shake detection sensor such as an angular velocity sensor is used to detect the amount of camera shake. Then, based on camera shake information detected by the shake detection sensor, part or all of the photographing optical system is driven to correct image shake. In the image blur correction device, in order to satisfactorily correct a shake caused by a shake or a vibration having a frequency distribution similar to a shake, a shake detection sensor and an optical system for shake correction corresponding to the shake, a shake detection sensor and a drive are selected. The response frequency band of the mechanism is set.

  Patent Document 1 uses acceleration information to improve image degradation caused by so-called parallel shake, which is applied in the horizontal direction or vertical direction in a plane orthogonal to the optical axis of the camera, that is, vibration that cannot be detected only by an angular velocity sensor. An imaging device is disclosed.

JP 2012-88466 A

However, the image pickup apparatus disclosed in Patent Document 1 can improve image deterioration due to parallel shake, but corrects for an angular velocity sensor output that is unrelated to camera shake that occurs when acceleration is applied to an angular velocity sensor that is an angular velocity detection means. I can't.
An object of the present invention is to provide an imaging apparatus capable of performing image blur correction with high accuracy even when acceleration is applied to the angular velocity detection means.

  An image pickup apparatus according to an embodiment of the present invention is an image pickup apparatus that drives a shake correction unit to correct a shake of a captured image, and detects an angular velocity signal indicating a shake applied to the image pickup apparatus; Acceleration detecting means for detecting acceleration applied to the imaging device; angular velocity correcting means for correcting the angular velocity signal based on the detected acceleration; and driving the shake correcting means based on the corrected angular velocity signal. Control means.

  According to the imaging apparatus of the present invention, it is possible to perform highly accurate image blur correction even when acceleration is applied to the angular velocity detection means.

It is a figure which shows the structural example of the imaging device of this embodiment. It is a figure which shows the structural example of a shift lens drive control part. It is a figure explaining the relationship between the drive vibration direction of an angular velocity sensor vibrator | oscillator, a detection vibration generation direction, and an angular velocity detection direction. It is a figure which shows the structural example of a shake detection part. It is a figure which shows the structural example of an anti-vibration control part. It is a figure which shows the structural example of an angular velocity correction | amendment part. It is a flowchart explaining the operation processing of an imaging device. It is a figure which shows the structure of an angular velocity correction | amendment part. It is a flowchart explaining the operation processing of an imaging device.

FIG. 1 is a diagram illustrating a configuration example of an imaging apparatus according to the present embodiment.
The image pickup apparatus shown in FIG. 1 includes a zoom unit 101 including a zoom lens that performs zooming, and a zoom drive control unit 102 that drives and controls the zoom unit 101. In addition, the imaging apparatus includes a shift lens (IS unit) 103 that functions as a shake correction unit that can move in a plane substantially perpendicular to the optical axis, and a shift lens drive control unit that drives and controls the shift lens 103 ( IS drive control unit) 104. IS is an abbreviation for Image Stabilizer. The shift lens drive control unit 104 drives the shift lens 103 to correct shake of the captured image caused by camera shake. The zoom drive control unit 102 and the shift lens drive control unit 104 stop the supply of drive power to the zoom unit 101 and the shift lens 103, respectively, during power saving.

  Further, the imaging apparatus includes an aperture / shutter unit 105 that performs an aperture operation and a shutter operation of the optical system, and an aperture / shutter drive control unit 106 that drives and controls the aperture / shutter unit 105. The imaging apparatus also converts a focus unit 107 that performs focus adjustment using a lens for focus adjustment, a focus drive control unit 108 that drives and controls the focus unit 107, and an optical image that passes through each lens group into an electrical signal. An image pickup unit 109 including an image pickup element that performs the image pickup is provided.

  In the imaging apparatus, the conversion process of the electrical signal output from the imaging unit 109 into the video signal is performed by the imaging signal processing unit 110, and processing according to the use of the video signal output from the imaging signal processing unit 110 is performed. This is performed by the video signal processing unit 111. The display unit 112 including a display performs image display as necessary based on the signal output from the video signal processing unit 111.

  In addition, the imaging apparatus includes a power supply unit 113 that supplies power to the entire imaging apparatus according to applications, an external input / output terminal unit 114 for inputting / outputting communication signals and video signals to / from the outside, and an imaging apparatus. An operation unit 115 for operation is provided. Various data such as video information obtained by photographing is stored in the storage unit 116, and the control of the entire imaging apparatus is performed by the control unit 117.

Next, the operation of the imaging apparatus having the above configuration will be described.
The operation unit 115 includes a shutter release button (not shown) configured so that the first switch (SW1) and the second switch (SW2) are sequentially turned on in accordance with the pressing amount. The first switch (SW1) is turned on when the shutter release button is depressed approximately halfway, and the second switch (SW2) is turned on when the shutter release button is depressed to the end.

  When the first switch (SW1) is turned on, the focus drive control unit 108 drives the focus unit 107 to perform focus adjustment, and the aperture / shutter drive control unit 106 drives the aperture / shutter unit 105 to perform exposure. Set the volume appropriately. When the second switch (SW2) is turned on, an optical image is exposed to the imaging unit 109, and image data obtained based on the electrical signal converted by the imaging element is stored in the storage unit 116. At this time, if there is an instruction to turn on the image stabilization from the operation unit 115, the control unit 117 instructs the shift lens drive control unit 104 to perform the image stabilization operation, and the shift lens drive control unit 104 that has received this instruction Anti-vibration operation is performed until the instruction is given. In addition, when the operation unit 115 has not been operated for a certain period of time, the control unit 117 issues an instruction to shut off the power source of the display included in the display unit 112 for power saving.

  In addition, the imaging device can select one of the still image shooting mode and the moving image shooting mode by operating the operation unit 115, and each actuator (movable element) constituting the imaging device in each shooting mode. The operating conditions can be changed.

  When an instruction for zooming with a zoom lens is input via the operation unit 115, the zoom drive control unit 102 that has received the instruction via the control unit 117 drives the zoom unit 101 to indicate the zoom position indicated. Move the zoom lens to. Further, based on the image information processed by the imaging signal processing unit 110 and the video signal processing unit 111, the focus drive control unit 108 drives the focus unit 107 to perform focus adjustment.

FIG. 2 is a diagram illustrating a configuration example of the shift lens drive control unit.
The shift lens drive control unit 104 includes a pitch direction gyro unit 201a and a yaw direction gyro unit 201b that function as a vibration detection unit that detects vibration applied to the imaging apparatus.

  The pitch direction gyro unit 201a detects a shake in the vertical direction (pitch direction) of the imaging apparatus in the normal posture (the posture in which the length direction of the image frame substantially matches the horizontal direction). The yaw direction gyro unit 201b detects a shake in the horizontal direction (yaw direction) of the imaging apparatus in the normal posture.

  Based on the shake signal of the pitch direction gyro unit 201a, the image stabilization control unit 202a calculates a shift lens correction position control signal in the pitch direction. Similarly, the image stabilization control unit 202b calculates a shift lens correction position control signal in the yaw direction based on the shake signal from the yaw direction gyro unit 201b. A magnet is attached to the shift lens 103, and the position of the shift lens 103 in the pitch direction and the yaw direction is detected by detecting the magnetic field of the magnet with the Hall elements of the position detectors 205a and 205b. That is, the position detection units 205a and 205b function as position detection means for detecting the position of the shift lens.

  The PID unit 203a and the PID unit 203b function as feedback control means. The PID unit 203a and the PID unit 203b obtain a control amount from the deviation between the shift lens correction position control signal of the image stabilization control unit 202a and 202b and the position signal of the position detection unit 205a and 205b, respectively, and output a drive command signal To do.

  The drive unit 204a and the drive unit 204b function as drive means for driving the shift lens 103 based on the drive command signals sent from the PID units 203a and 203b, respectively. As described above, the PID units 203a and 203b perform feedback control such that the position signal converges on the corrected position control signals respectively transmitted from the image stabilization control units 202a and 202b.

  The shift lens correction position control signal in the pitch direction calculated by the image stabilization control unit 202a based on the shake signal from the pitch direction gyro unit 201a is a signal representing the movement target position (shake correction position) in the pitch direction. Similarly, the shift lens correction position control signal in the yaw direction calculated by the image stabilization control unit 202b based on the shake signal from the yaw direction gyro unit 201b is a signal representing the movement target position (shake correction position) in the yaw direction. .

  The position of the shift lens 103 is moved in a direction in which image blur due to shake of the imaging apparatus is corrected by a shift lens correction position control signal output from each of the image stabilization controllers 202a and 202b. As a result, even if the shift lens 103 that performs shake correction moves in the vertical and horizontal directions orthogonal to the optical axis and a camera shake or the like occurs in the imaging apparatus, image shake can be prevented.

FIG. 3 is a diagram for explaining the relationship among the drive vibration direction, detected vibration generation direction, and angular velocity detection direction of the angular velocity sensor vibrator.
When the vibrator having the mass m of the vibrator is oscillating at a speed V in the driving vibration direction and rotating at an angular speed ω around the center axis of the vibrator, a Coriolis force of F = 2 mV × ω is perpendicular to the driving vibration direction. Is generated in the direction, and the detection vibration is excited in the detection vibration generation direction of the vibrator. The angular velocity can be detected by detecting the distortion of the vibrator due to the detected vibration at this time as an electric signal and processing the detected vibration. A silicon wafer is used as the material of the vibrator, and a piezoelectric thin film and electrodes are formed on the silicon surface. A voltage is applied to the drive electrode to induce drive vibration by the reverse piezoelectric effect, and distortion caused by the detected vibration is reduced. It detects as an electric charge by the piezoelectric effect. In the example shown in FIG. 3, a tuning-fork-shaped vibrator shape is shown, but other vibrator shapes such as a rectangular parallelepiped shape and a comb-tooth shape may be used.

FIG. 4 is a diagram illustrating a configuration example of the shake detection unit.
FIG. 4 shows a circuit configuration for driving the vibrator and detecting the angular velocity. The drive circuit 401 applies a voltage to the drive electrode of the vibrator 301 to drive the vibrator. In addition, the drive circuit 401 has a negative feedback configuration including an AGC circuit that controls a drive voltage applied to the element in accordance with a current proportional to the mechanical vibration amplitude output from the vibrator 301. Is controlled to be constant. AGC is an abbreviation for Auto Gain Control.

  In addition, the transducer 301 generates a detection signal having an amplitude proportional to the input angular velocity signal. The generated detection signal is amplified by the signal amplification unit 402, and the processing unit 403 performs synchronous detection processing of the drive frequency signal and the detection signal of the vibrator, and the voltage and drive frequency proportional to the generated angular velocity are superimposed. Generate a signal. The LPF 404 can obtain a DC voltage proportional to the angular velocity by smoothing the generated signal. When the angular velocity is input in this way and the Coriolis force is generated, an angular velocity output is obtained. However, even when acceleration is applied to the angular velocity sensor, the vibrator is excited in the detected vibration direction, so that when the acceleration is applied, an angular velocity output is output.

FIG. 5 is a diagram illustrating a configuration example of the image stabilization control unit.
An angular velocity sensor 201 serving as a shake detection unit detects shake information and outputs a shake signal. In this example, the angular velocity sensor 201 is described as an analog interface angular velocity sensor, but a digital interface angular velocity sensor may be applied. An analog amplifier 502 serving as a signal amplifying unit amplifies the shake signal output from the angular velocity sensor 201 to a specific magnification. A shake detection signal A / D conversion unit 503 digitizes the amplified shake signal to generate a digital signal.

  The acceleration component detection unit 501 is an acceleration detection unit that detects acceleration applied to the angular velocity sensor 201 of the imaging apparatus and outputs an acceleration component. As the acceleration component detection unit 501, an element that directly detects acceleration, such as an acceleration sensor, is used. Note that the acceleration component detection unit 501 may estimate acceleration based on a control value of an actuator controlled by the imaging apparatus, and detect the acceleration based on the estimated value. As an estimated value of the acceleration component, for example, an integral control value used in PID control of shift lens control can be cited.

  The angular velocity correction unit 504 receives an acceleration component output from the acceleration component detection unit 501 and a digital signal (angular velocity signal) output from the shake detection signal A / D conversion unit 503. The angular velocity correction unit 504 executes an angular velocity signal correction process based on the acceleration component and outputs it (angular velocity output). The angular velocity output is processed by a digital high-pass filter (hereinafter referred to as HPF) 505 and a digital low-pass filter (hereinafter referred to as LPF) 506, which are digital filter means capable of changing the cutoff to pass a predetermined frequency. The filtered shake signal is converted into the actual shift lens drive amount target position by the shake correction amount calculation means 507, and then the control amount is calculated by the PID control unit 203 from the current position and the target position of the shift lens. The shake correction unit is driven to correct the camera shake.

FIG. 6 is a diagram illustrating a configuration example of the angular velocity correction unit.
The angular velocity correction unit 504 includes an output correction unit 601, a phase adjustment filter 602, and a band limiting filter 603.
The band limiting filter 603 extracts a frequency band component necessary for camera shake correction from the acceleration components output by the acceleration component detection unit 501. For this purpose, the band limiting filter 603 has a high-pass filter and a low-pass filter that are used to extract frequency band components. The phase adjustment filter 602 adjusts the phase of the output of the band limiting filter 603 using a phase advance filter and a phase delay filter.

In the output correction unit, the angular velocity correction amount is calculated and output by the shake detection signal A / D conversion unit 503 and the phase adjustment filter 602 as in the following equation (1). Here, the correction amount of the angular velocity output by the acceleration component can be adjusted by the coefficient K.
Angular velocity correction unit output = shake detection signal A / DK × band limiting filter output (1)
In the above equation (1), K is an angular velocity correction coefficient based on an acceleration component.

FIG. 7 is a flowchart illustrating an operation process of the imaging apparatus according to the first embodiment.
First, the control unit 117 determines whether or not to turn on the camera shake correction mode (step S101). The camera shake correction mode is an operation mode for executing camera shake correction. If the control unit 117 determines to turn off the camera shake correction mode, the process proceeds to step S107. When the control unit 117 determines to turn on the camera shake correction mode, the process proceeds to step S102.

  In step S102, the shake detection signal A / D conversion unit 503 acquires an angular velocity signal. The shake detection signal A / D conversion unit 503 outputs the acquired angular velocity signal to the angular velocity correction unit 504. Subsequently, the acceleration component detection unit 501 detects the acceleration applied to the angular velocity sensor 201 and outputs it to the angular velocity correction unit 504.

  Next, the angular velocity correction unit 504 performs angular velocity correction based on the data output in steps S102 and S103 (step S104). Thereby, the corrected angular velocity signal is output. Subsequently, the control unit 117 performs a camera shake correction calculation based on the corrected angular velocity signal output in step S104 (step S105). Then, the control unit 117 drives the shift lens to the position calculated by the camera shake correction calculation (step S106).

  Next, the control unit 117 determines whether to turn off the power (step S107). If the power is not turned off, the process proceeds to step S101. If the power is turned off, the process ends.

(Example 2)
FIG. 8 is a diagram illustrating a configuration of an angular velocity correction unit according to the second embodiment.
In the imaging apparatus according to the second embodiment, the angular velocity correction unit 504 performs angular velocity correction using the focal length information 801 of the zoom lens and the recording mode information 802 of the imaging device. Focal length information 801 and recording mode information 802 are stored in a predetermined storage unit. The recording mode information 802 is information indicating the recording mode of the imaging apparatus. The recording mode information 802 indicates, for example, either a moving image shooting mode or a still image shooting mode. The configuration other than the configuration related to the angular velocity correction is the same as that of the first embodiment.

FIG. 9 is a flowchart illustrating an operation process of the imaging apparatus according to the second embodiment.
Steps S201 to S203 are the same as steps S101 to S103 in FIG.
In step S204, the angular velocity correction unit 504 acquires focal length information 801. When the focal length indicated by the focal length information 801 is long, an angular velocity sensor output error due to acceleration greatly affects. Therefore, the angular velocity correction unit 504 increases the correction by the acceleration component by increasing the angular velocity correction coefficient K as the focal length is longer. Also, as the focal length is longer, the low frequency fluctuation becomes more conspicuous, so the angular velocity correction unit 504 lowers the cutoff frequency of the band limiting filter 603. As a result, the frequency band extracted by the band limiting filter 603 becomes a low frequency.

  In step S205, the control unit 117 acquires the recording mode information 802. Then, the control unit 117 determines whether the recording mode of the imaging apparatus is the moving image shooting mode. If the recording mode of the imaging device is not the moving image shooting mode but the still image shooting mode, the process proceeds to step S208. If the recording mode of the imaging device is the moving image shooting mode, the process proceeds to step S206.

  Next, the control unit 117 changes the cutoff frequency of the band limiting filter 603 to a cutoff frequency suitable for moving images. In other words, in the video shooting mode, scenes where acceleration is applied to the imaging apparatus such as walking shots increase, so the cutoff frequency of the band limiting filter 603 is set to a higher frequency than during still image shooting, and emphasis is placed on higher frequencies. Correction. The control unit 117 may increase the correction by the acceleration component by increasing the angular velocity correction coefficient K.

  Next, the control unit 117 changes the phase adjustment filter 602 (step S207). That is, when the band limiting filter 603 is changed, the phase of the band limiting filter 603 output is also changed. Therefore, the control unit 117 changes the phase adjustment filter 602 so as to compensate the band limiting filter 603 output phase. Then, the process proceeds to step S210.

  In step S208, the control unit 117 changes the cutoff frequency of the band limiting filter 603 to a cutoff frequency suitable for a still image. In the still shooting mode, the imaging apparatus is firmly held, and the scene where acceleration is applied to the imaging apparatus is reduced. Therefore, the control unit 117 sets the frequency of the band limiting filter 603 to a frequency lower than that during moving image shooting, and performs correction mainly on the low frequency. At this time, the control unit 117 may reduce the correction by the acceleration component by reducing the angular velocity correction coefficient K.

  Next, the control unit 117 changes the phase adjustment filter 602 (step S209). That is, when the band limiting filter 603 is changed, the phase of the band limiting filter 603 output is also changed. Therefore, the control unit 117 changes the phase adjustment filter 602 so as to compensate the band limiting filter 603 output phase.

  Next, the output correction unit 601 of the angular velocity correction unit 504 executes angular velocity correction according to the above-described equation (1), and outputs a corrected angular velocity signal (step S210). Subsequently, the control unit 117 performs a camera shake correction calculation based on the corrected angular velocity signal output in step S210 (step S211). Then, the control unit 117 drives the shift lens to the position calculated by the camera shake correction calculation (step S212).

  Next, the control unit 117 determines whether to turn off the power (step S107). If the power is not turned off, the process proceeds to step S201. If the power is turned off, the process ends.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

(Other examples)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

103 IS unit 117 control unit

Claims (10)

An imaging apparatus that drives shake correction means to correct shake of a captured image,
Angular velocity detection means for detecting angular velocity indicating a shake applied to the imaging device;
Acceleration detecting means for detecting acceleration applied to the angular velocity detecting means;
Angular velocity correction means for correcting the angular velocity based on the detected acceleration;
An imaging apparatus comprising: control means for driving the shake correction means based on the corrected angular velocity. The angular velocity correction means includes
Filter means for extracting, as an acceleration component, a frequency band component necessary for correcting a shake of the captured image set in advance from the acceleration,
The imaging apparatus according to claim 1, wherein the angular velocity is corrected based on the extracted acceleration component. The angular velocity correction means includes
Phase adjustment means for adjusting the phase of the extracted acceleration component;
The imaging apparatus according to claim 2, wherein the angular velocity is corrected based on an acceleration component whose phase is adjusted. The arithmetic means corrects the angular velocity by multiplying the acceleration component by a coefficient corresponding to a focal length of the imaging apparatus and subtracting an acceleration component multiplied by the coefficient from the angular velocity. The imaging device according to claim 2 or claim 3. The imaging apparatus according to claim 4, wherein the arithmetic unit increases a coefficient by which the acceleration component is multiplied as the focal length is longer. The imaging apparatus according to claim 2, wherein a lower frequency is set as a frequency band component extracted by the filter unit as the focal length is longer. When the operation mode of the imaging device is the moving image shooting mode, a frequency higher than the frequency band component set when the operation mode is the still image shooting mode is set as the frequency band component extracted by the filter unit. The imaging apparatus according to any one of claims 2 to 6, wherein the imaging apparatus is configured as follows. The imaging apparatus according to claim 1, wherein the acceleration detection unit is an acceleration sensor. The acceleration detection means detects an acceleration component estimated based on a control value of an actuator controlled by the imaging device as an acceleration applied to the imaging device. The imaging device described. A method of controlling an image pickup apparatus that drives shake correction means to correct shake of a captured image,
Detecting an angular velocity indicating a shake applied to the imaging device by an angular velocity detecting means;
Detecting acceleration applied to the angular velocity detection means;
Correcting the angular velocity based on the detected acceleration;
And a step of driving the shake correcting means based on the corrected angular velocity.

Images