JP6485499B2 - Blur correction device and optical apparatus - Google Patents

Description

  The present invention relates to a shake correction apparatus and an optical apparatus.

There is a technique for performing optical image stabilization based on a signal from an angular velocity sensor (gyro). In this technique, it is necessary to accurately obtain the reference value (gyro output value at 0 deg / s) of the angular velocity sensor. It is difficult to find accurately.
Therefore, a technique has been proposed in which the output signal of the angular velocity sensor is calculated by LPF (low-pass filter) processing, and the reference value is corrected using motion vector information (see Patent Document 1).

Japanese Patent No. 4419466

However, the blur on the imaging surface detected as a motion vector includes an error component of a reference value and a center bias component. However, in Patent Document 1, the motion vector information including the center bias component is used as a reference. Since the value is corrected, accurate reference value correction cannot be performed.
An object of the present invention is to provide a shake correction apparatus and an optical apparatus that can accurately correct a reference value.

The present invention provides a blur correction unit that corrects blur of a subject image by moving, an angular velocity sensor that detects an angular velocity, a reference value calculation unit that calculates a reference value of an output signal of the angular velocity sensor, and the subject image . a motion vector calculating unit for calculating a first motion vector from an image signal obtained by imaging, and the first motion vector, control for moving the pre-Symbol blur correction unit toward the center of the movable range of the shake correction unit Based on the second motion vector calculated based on the amount, the correction unit corrects the reference value, and the blur correction unit based on the output signal of the angular velocity sensor and the reference value corrected by the correction unit The present invention relates to a shake correction apparatus comprising: a target position calculation unit that calculates a target position at which the camera moves; and a drive unit that drives the shake correction unit based on the target position .
The present invention also relates to an optical apparatus including the shake correction device.

  ADVANTAGE OF THE INVENTION According to this invention, the blurring correction apparatus and optical instrument which can correct | amend an exact reference value can be provided.

It is sectional drawing which shows typically a camera provided with the blurring correction apparatus of 1st Embodiment. It is a block diagram of the blurring correction apparatus of 1st Embodiment. It is the flowchart which showed the flow of operation | movement of the blurring correction apparatus of 1st Embodiment. It is a figure explaining a reference value calculating part, (a) is a reference value calculating part, (b) is a figure showing LPF of a reference value calculating part. It is a flowchart which shows a reference value correction calculation. (A) is a graph which shows the reference value after correction | amendment, (b) is a graph which shows the direction of a motion vector. It is the graph which compared the case where correction | amendment of this embodiment is performed (solid line), and the case where correction | amendment is not performed (dotted line), (a) shows a calculation error, (b) shows image surface blurring amount. . It is the graph which compared the image plane blurring amount during exposure. It is the graph which showed the time-dependent change of the gain with respect to a correction value. It is a block diagram of the blurring correction apparatus of 3rd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings and the like.
FIG. 1 is a cross-sectional view schematically showing a camera 1 including the shake correction apparatus of the first embodiment.
The camera 1 is a digital single-lens reflex camera, and includes a camera housing 1A and a lens barrel (optical member) 1B that is detachably attached to the camera housing 1A.

  The camera housing 1A includes a camera CPU 2A, an image sensor 3, a recording medium 13, an EEPROM 14, a signal processing circuit 15, an AF sensor 16, a release switch 17, a rear liquid crystal 18, a mirror 19, and a shutter 20.

The camera CPU 2A is a central processing unit that performs overall control of the camera 1, and constitutes a part of the shake correction device of the present embodiment.
The imaging element 3 is an element that captures a subject image formed by the photographing lenses (4, 5, 6), exposes the subject light to convert it into an electrical image signal, and outputs it to the signal processing circuit 15. The image pickup device 3 is configured by an element such as a CCD or a CMOS.

The recording medium 13 is a medium for recording captured image data, and an SD card, a CF card, or the like is used.
The EEPROM 14 is a memory that stores adjustment value information such as the gain value of the angular velocity sensor 12, information unique to the lens barrel, and the like, and outputs the memory to the CPU 2.
The signal processing circuit 15 is a circuit that receives an output from the image sensor 3 and performs processing such as noise processing and A / D conversion.

The AF sensor 16 is a sensor for performing AF (automatic focus adjustment), and a CCD or the like can be used.
The release switch 17 is a member that performs a photographing operation of the camera 1 and is a switch that operates a shutter driving timing and the like.

  The rear liquid crystal 18 is provided on the rear surface of the camera housing 1A of the camera 1 and displays a subject image (reproduced image, live view image) photographed by the image sensor 3 and information (menu) related to operation. It is.

  The shutter 20 is disposed behind the mirror 19. Subject light is incident on the shutter 20 when the mirror 19 rotates upward and becomes ready for photographing. The shutter 20 travels through a shutter curtain in response to a shooting instruction from the release switch 17 or the like, and controls subject light incident on the image sensor 3.

  The lens barrel 1B includes a zoom lens group 4, a focus lens group 5, a shake correction lens group (optical element) 6, a zoom lens group drive mechanism 7, a focus lens group drive mechanism 8, and a shake correction lens group drive mechanism (optical element drive). Part) 9, an aperture 10, an aperture drive mechanism 11, an angular velocity sensor 12, and a lens CPU 2B.

  The lens CPU 2B calculates the movement amount of the lens groups such as the zoom lens group 4, the focus lens group 5, and the blur correction lens group 6. The zoom lens group drive mechanism 7, the focus lens group drive mechanism 8, the blur correction lens group drive mechanism 9 and the aperture drive mechanism 11 are instructed to move the zoom lens group 4, the focus lens group 5, and the blur correction lens group 6. Move.

The zoom lens group 4 is a lens group that is driven by the zoom lens group drive mechanism 7 and moves along the optical axis direction to continuously change the magnification of the image.
The focus lens group 5 is a lens group that is driven by the focus lens group drive mechanism 8 and moves in the optical axis direction to focus.
The shake correction lens group 6 (optical element) is a lens group that is optically shake-corrected and driven on a plane perpendicular to the optical axis by a shake correction lens group drive mechanism 9 such as a VCM.

The diaphragm 10 is a mechanism that is driven by the diaphragm drive mechanism 11 and controls the amount of subject light passing through the photographing lenses (4, 5, 6).
The angular velocity sensor 12 is a sensor that detects an angular velocity of a shake that occurs in each sensor unit.

FIG. 2 is a block diagram of the shake correction apparatus 100 of the present embodiment.
The shake correction apparatus 100 includes a camera CPU 2A, a lens CPU 2B, an angular velocity sensor 12, a shake correction lens group drive mechanism (lens drive unit) 9, a lens position detection unit 21, and a shake correction lens group 6.

The camera CPU 2 </ b> A includes an image sensor 3, a signal processing unit 40, and a motion vector calculation unit 41.
The lens CPU 2B includes an amplification unit 31, a first A / D conversion unit 32, a second A / D conversion unit 33, a reference value calculation unit 34, a reference value correction amount calculation unit 35, and a target position calculation unit 36 including an integration unit therein. A center bias calculator 37, a center bias remover 38, and a drive amount calculator 39.
The angular velocity sensor 12 is a sensor such as a vibrating gyroscope that detects angular velocities around the X axis (Pitch), Y axis (Yaw), and Z axis (Roll) of the lens barrel 1B.

The amplifying unit 31 amplifies the output of the angular velocity sensor 12.
The first A / D converter 32 performs A / D conversion on the output of the amplifier 31.
The reference value calculation unit 34 calculates the reference value of the vibration detection signal (output of the first A / D conversion unit 32) obtained from the angular velocity sensor 12.
Then, the reference value calculated by the reference value calculation unit 34 is subtracted from the output of the first A / D conversion unit 32 by the subtraction unit 43.
The target position calculation unit 36 calculates the target position of the blur correction lens group 6 based on the output of the angular velocity sensor 12 after the reference value is subtracted by the subtraction unit 43.

The center bias calculation unit 37 biases the centripetal force for moving the image blur correction lens 6 toward the center of the movable range based on the target position of the image blur correction lens 6 calculated by the target position calculation unit 36. Calculate as a quantity.
Then, the control position of the image blur correction lens 6 is calculated by subtracting the calculated bias amount from the target position of the image blur correction lens 6.
By performing the centering bias processing in this way, it is possible to effectively prevent the image blur correction lens 6 from colliding with the hard limit, and it is possible to improve the appearance of the captured image.

  The drive amount calculation unit 39 is a blur correction lens group obtained from the target position from the target position calculation unit 36 and the value detected by the lens position detection unit 21 and A / D converted by the second A / D conversion unit 33. 6 is used to calculate the driving amount of the blur correction lens group driving mechanism 9.

The image sensor 3 is provided on the planned focal plane of the photographing optical system. The image pickup device 3 is composed of a device such as a CCD or a CMOS, and generates an analog image signal by photoelectrically converting an input subject image.
The signal processing unit 40 performs predetermined processing on the image signal generated by the image sensor 3.

The motion vector calculation unit 41 calculates a motion vector (first motion vector) indicating the motion of the image (motion direction, amount of motion) from the captured image processed by the signal processing unit 40.
Specifically, the motion vector calculation unit 41 detects the motion direction and the motion amount of the image by comparing the luminance information included in two consecutive frame image data captured by the image sensor 3. Calculate the motion vector.

The center bias removing unit 38 is a bias amount calculated by the center bias calculating unit 37 (subtracted from the target position of the image blur correction lens 6) from the first motion vector (MV1) that is the output of the motion vector calculating unit 41. Is subtracted.
The reference value correction amount calculation unit (reference value correction unit) 35 calculates a reference value correction amount based on the second motion vector (MV2) from which the center bias amount has been removed by the center bias removal unit 35.
Then, the subtraction unit (reference value correction unit) 42 subtracts the reference value correction amount obtained by the reference value correction amount calculation unit 35 from the output of the reference value calculation unit 34.

Next, an operation flow of the shake correction apparatus 100 according to the present embodiment will be described.
FIG. 3 is a flowchart showing an operation flow of the shake correction apparatus 100 of the present embodiment.

  After the camera 1 is turned on, the shake correction apparatus 100 starts a calculation for optical image stabilization. Depending on the camera, when the half-push switch 45 is pressed, the shake correction apparatus 100 starts calculation for optical image stabilization (step S001).

After the output of the angular velocity sensor 12 is amplified by the amplification unit 31, it is A / D converted by the first A / D conversion unit 32 (step S002).
The reference value calculation unit 34 calculates a reference value (a value corresponding to zero deg / s) of the calculated angular velocity based on the signal after A / D conversion of the output of the angular velocity sensor 12. Since the reference value of the angular velocity changes depending on the temperature characteristic, the drift characteristic immediately after startup, etc., for example, the stationary output of the angular velocity sensor 12 at the time of factory shipment cannot be used as the reference value.

  As a method for calculating the reference value, a method of calculating a moving average for a predetermined time and a method of calculating by LPF processing are known. In the present embodiment, reference value calculation by LPF processing is used.

  4A and 4B are diagrams for explaining the reference value calculation unit 34. FIG. 4A shows the reference value calculation unit 34 (HPF), and FIG. 4B shows the LPF 34a of the reference value calculation unit 34. .

  The cut-off frequency fc of the LPF 34 is generally set to a low frequency of about 0.1 [Hz]. This is because camera shake has a dominant frequency of about 1 to 10 [Hz]. If the fc is 0.1 [Hz], there is little influence on the camera shake component, and good blur correction can be performed.

  However, during actual shooting, low-frequency motion such as fine adjustment of the composition (a level at which panning cannot be detected) is added, which may cause an error in the ω0 calculation result. In addition, since fc is low (time constant is large), there is a problem that it takes time to converge to a true value when the error is once increased. In the present embodiment, this ω0 error is corrected.

Returning to FIG. 3, when the information of the first motion vector MV1 is updated (S004, YES), the process proceeds to S005, and when it is not updated (S004, NO), the process proceeds to S006. The description of S004 to S005 will be described later in detail.
In addition, since information on the first motion vector MV1 cannot be obtained during exposure, this step is performed until immediately before the exposure.
The outputs of the angular velocity sensor 12 after subtracting the reference value are integrated, and the target position of the shake correction lens group 6 is calculated based on the focal length, subject distance, shooting magnification, and shake correction lens characteristic information (S006).
Center bias processing is performed to prevent the blur correction lens group 6 from reaching the movable end (S007).

  There are various center bias processing methods such as a method of setting a bias amount according to target position information, HPF processing, incomplete integration processing (in S006), and the method is not limited here.

The lens driving amount is calculated from the difference between the target position information including the center bias component and the blur correction lens position information (S008).
The blur correction lens group 6 is driven to the target position (S009), and the process returns to S002.

Next, reference value correction (S004 to S005, S011 to S016) will be described. FIG. 5 is a flowchart showing the reference value correction calculation.
As described above, when the information of the first motion vector MV1 is updated (S004), the process proceeds to S005. If it has not been updated, the process proceeds to S006.
Since the optical blur correction control cycle is sufficiently early with respect to the MV1 update cycle, the same arithmetic processing as in normal image stabilization is performed until MV1 is updated. Here, it is assumed that the control period of optical blur correction is 1 [ms] and the update period of the first motion vector MV1 is 33 [ms] (= 30 [fps]). A well-known technique is used for the calculation method of the first motion vector MV1.

All the received first motion vectors MV1 are summed (S011).
The center bias component calculated in S007 is converted to the same scale as the first motion vector MV1 (S012).
The conversion method is calculated based on the focal length, the subject distance, the shooting magnification, and the resolution information of the first motion vector MV1.
Bias_MV = Bias_θ * f1 + β / MV_pitch

Bias_MV: Center bias component (same motion vector scale)
Bias_θ: Center bias component (angle)
f: Focal length β: Image magnification MV_pitch: MV1 pitch size

  In addition, since a delay time occurs until the first motion vector MV1 is detected, it is preferable that the center bias component also has a delay time equivalent to that of the first motion vector MV1. For example, if there is a delay time of 3 frames at 30 [fps], the delay is about 100 [ms]. Therefore, the center bias component included in the first motion vector MV1 can be calculated more accurately by using the bias information before 100 [ms].

The center bias component calculated in S012 is subtracted from the first motion vector MV1 (S013). Thereby, the information of the second motion vector MV2 due to the reference value error can be acquired.
A difference: MV_diff between the latest second motion vector MV2 (n) and the second motion vector MV2 (n-1) one frame before is acquired (S014).
An amount for correcting the reference value is set based on MV_diff. As the reference value, a correction amount is set based on the following idea (S015).

MV_diff> 0: ω0_comp = −ω0_comp_def
MV_diff <0: ω0_comp = + ω0_comp_def
MV_diff = 0: ω0_comp = 0

ω0_comp: reference value correction amount ω0_comp_def: reference value correction constant

  Ω0_comp calculated in S015 is subtracted from the reference value calculated in S003 (S016). Specifically, the value of V4 ′ in FIG. 4B is corrected.

FIG. 6A is a graph showing a reference value obtained by correcting the value of V4 ′ in FIG. A dotted line in the figure indicates a reference value when correction is not performed according to the present embodiment, and a solid line in the figure indicates a reference value when correction is performed according to the present embodiment.
FIG. 6B is a graph showing the direction of the second motion vector MV2. For example, when the second motion vector MV2 is in the plus direction as shown at time t1 in FIG. 6B, the reference value is corrected to minus as shown in (a).

Thereafter, the reference value changes according to the value calculated by the reference value calculation unit 34 until time t3.
When the second motion vector MV2 is confirmed in the positive direction at time t3, the reference value is corrected to a negative value. In the present embodiment, the correction amount at this time is constant as at time t1.
Thereafter, the reference value changes according to the value calculated by the reference value calculation unit 34 between the times when the second motion vector MV2 is confirmed.
When the second motion vector MV2 is confirmed in the positive direction, the reference value is corrected to a certain amount minus.
Further, when the second motion vector MV2 is confirmed in the minus direction at times t22 and t25 in the figure, the reference value is corrected to a certain amount plus.

  By correcting the reference value as described above, the correction value can take a value close to the true value as shown in FIG.

  FIG. 7 is a graph comparing the case where the correction with respect to the reference value of the present embodiment is performed (solid line) and the case where the correction with respect to the reference value is not performed (dotted line). (A) shows the calculation error, and (b) shows the image plane blurring amount. As shown in the figure, according to the present embodiment, the calculation error for the true value is reduced. In addition, when the correction is performed on the reference value, the image plane blurring amount is reduced as compared with the case where the correction on the reference value is not performed.

  FIG. 8 is a graph comparing image plane blurring amount during exposure. In the figure, the case where no blur correction is performed is indicated by a broken line, and the case where the correction according to the present embodiment is performed is indicated by a one-point difference line. In addition, a continuous line is 2nd Embodiment mentioned later.

The correction of the reference value using the second motion vector MV2 is only during the exposure preparation period (during half-press vibration isolation and during moving image shooting), and normal reference value calculation is performed during exposure.
As shown in the figure, according to the present embodiment, the reference value correction is performed only during the exposure preparation period, but the exposure can be started in a state where the reference value immediately before the exposure is closer to the true value. In this case, it is possible to perform good blur correction.

(Second Embodiment)
In the second embodiment, in S015 of FIG. 5 of the first embodiment, the predetermined value for correcting the reference value is changed according to the calculation time of the reference value. Since other processes are the same as those in the first embodiment, the description thereof is omitted.

In this embodiment, immediately after the start of blur correction, the gain is increased and the correction amount is increased as shown in FIG. Then, the time is reduced as time elapses from the start of blur correction calculation, and after a fixed time has elapsed, the correction amount is set to a fixed amount. This is because ω0 is large at the start of calculation. An amount for correcting the reference value is set based on MV_diff. The reference value is set based on the following idea.
MV_diff> 0:
ω0_comp = −ω0_comp_def * gain (t)
MV_diff <0:
ω0_comp = + ω0_comp_def * gain (t)

ω0_comp: reference value correction amount ω0_comp_def: reference value correction constant gain (t): correction value gain

  By making the reference value correction amount variable with time, the convergence of the reference value can be accelerated as shown by the solid line in FIG.

(Third embodiment)
FIG. 10 is a block diagram of a shake correction apparatus 200 according to the third embodiment of the present invention. In the third embodiment, a reference value correction execution / non-execution determination unit 44 and a changeover switch 45 are provided in the first embodiment shown in FIG.

  The determination unit 44 determines whether or not the reference value correction is performed based on the optical information (FIG. 8). Specifically, the reference value correction using the motion vector is not performed when the focus is out of focus and when the photographing magnification is larger than a predetermined value.

  The center bias removal unit 38 converts the center bias component into the same scale as the motion vector based on the subject distance information obtained from the distance encoder information. When the focus is out of focus, accurate subject distance information cannot be obtained, so that there is a problem that the center bias component cannot be removed accurately.

  Further, when the photographing magnification is larger than a predetermined value, the influence of parallel blur becomes large, and thus the detected motion vector information includes a parallel blur component. Since it is difficult to separate the reference value error from the parallel blur, there is a problem that the reference value cannot be corrected when the photographing magnification is large.

  As described above, the reference value correction using the motion vector is not performed when the focus is out of focus and when the photographing magnification is larger than a predetermined value.

As described above, this embodiment has the following effects.
(1) When correcting the reference value of the angular velocity sensor using the motion vector information, the center bias component included in the motion vector information is removed.
At this time, the center bias component can be more accurately removed by taking into consideration the focal length of the lens, subject distance, motion vector detection time delay, motion vector resolution, and the like, and converting to the same scale as the motion vector.
Using this motion vector information, if the value is changed to the plus side with respect to the value one frame before, the gyro reference value is offset to the minus side of the predetermined value. Similarly, if the value is changed to the minus side, Increase the value by a predetermined value.
With this process, the reference value can be corrected without being affected by the center bias component. In addition, even when the accuracy of the motion vector is deteriorated, since the adverse effect on the reference value correction is small, the problem of deterioration with respect to the conventional image stabilization accuracy is also reduced.

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
For example, based on the same idea as in the third embodiment, the reference value correction may not be performed under the following conditions.
(1) When the blur correction lens exceeds the movable end (calculation limit value) This is because the reference value cannot be corrected because a camera shake component is added to the motion vector information.
(2) When it is determined that subject blur is included in the motion vector information This is because the reference value error and subject blur cannot be separated.
(3) When it is determined that the reliability of the motion vector information is low Note that the reliability determination is omitted because it is a known technique.
(4) During composition change determination (5) During tripod determination In addition, although embodiment and a deformation | transformation form can also be used in combination suitably, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

  1: camera, 1A: camera housing, 1B: lens barrel, 2A: camera CPU, 2B: lens CPU, 3: image sensor, 4: zoom lens group, 5: focus lens group, 6: blur correction lens group, 7: Zoom lens group drive mechanism, 8: Focus lens group drive mechanism, 9: Blur correction lens group drive mechanism, 12: Angular velocity sensor, 21: Lens position detection unit, 31: Amplification unit, 32: First A / D conversion unit 33: second A / D conversion unit, 34: reference value calculation unit, 35: center bias removal unit, 35: reference value correction amount calculation unit, 36: target position calculation unit, 37: center bias calculation unit, 38: center Bias removal unit, 39: drive amount calculation unit, 40: signal processing unit, 41: vector calculation unit, 42: reference value correction unit, 43: subtraction unit, 100, 200: blur correction device

Claims (9)

A blur correction unit that corrects blur of the subject image by moving;
An angular velocity sensor for detecting angular velocity;
A reference value calculation unit for calculating a reference value of the output signal of the angular velocity sensor ;
A motion vector computing unit for computing a first motion vector from an image signal obtained by capturing the subject image;
Said first motion vector, by pre-Symbol second motion vector calculated on the basis of the control amount for moving the shake correction unit toward the center of the movable range of the blur correction unit, a correcting unit for correcting the reference value ,
A target position calculation unit that calculates a target position at which the blur correction unit moves based on the output signal of the angular velocity sensor and the reference value corrected by the correction unit;
A drive unit that drives the blur correction unit based on the target position;
An image stabilization apparatus comprising: The shake correction apparatus according to claim 1,
The correction unit uses the second motion vector obtained by removing the bias amount based on the target position for moving the blur correction unit toward the center of the movable range of the blur correction unit from the first motion vector. A blur correction device for correcting the reference value. The shake correction apparatus according to claim 2,
A bias calculation unit that adds a bias amount toward the center of the movable range of the shake correction unit by the target position;
A bias removal unit that calculates a second motion vector obtained by removing the bias amount from the first motion vector,
The blur correction device corrects the reference value by the second motion vector. The blur correction device according to any one of claims 1 to 3,
The shake correction apparatus, wherein the correction unit corrects the reference value based on a sign of the second motion vector. The blur correction device according to claim 3 ,
The bias removing unit includes:
A blur correction device that converts the bias amount into the same scale as the first motion vector based on optical information of an optical system that forms the subject image and resolution of the first motion vector. The blur correction device according to claim 2 or 3 ,
The blur correction device in which the bias amount has a delay time equivalent to a delay time of detection of the first motion vector. The blur correction apparatus according to any one of claims 2 , 3 , and 6 ,
The correction unit is
When the soft limit for moving the blur correction unit is exceeded When the optical system that forms the subject image is in an in-focus state,
When the optical device including the shake correction device is changing the composition,
When an optical device equipped with the shake correction device is in use of a tripod,
When the first motion vector is subject blur,
When the reliability of the first motion vector information is low, or when the shooting magnification is larger than a predetermined value,
A blur correction device that does not correct the reference value. In the blurring correction apparatus according to any one of claims 1 to 7,
The shake correction apparatus, wherein the correction unit has a larger amount of correcting the reference value as the time from the start of calculation of the reference value is shorter.   An optical apparatus comprising the shake correction device according to claim 1.

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