JP6414285B2 - 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 camera shake correction 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, but the reference value of the angular velocity sensor changes depending on drift characteristics immediately after startup, temperature characteristics, and the like. 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

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, a reference value is determined using motion vector information including a center bias component. Since the correction is performed, it is impossible to correct the reference value accurately.
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 includes a shake correction unit for correcting the blur of the subject image by moving, an angular velocity sensor for detecting an angular velocity, a reference value calculating unit for calculating a reference value of the output signal of the angular velocity sensor, the reference value calculation a storage unit for storing the reference value calculated by the section, by the output signal of the angular velocity sensor, and the target position calculation unit that the shake correction unit calculates a target position to move, thus the prior Symbol targets located a driving unit for driving the blur correction unit, a motion vector calculating unit for calculating a first motion vector of the previous SL object image, said first motion vector, movable of said drive unit said blur correcting unit the blur correction unit range and control for moving toward the center of the second motion vector obtained from, and a complement Tadashibu you correcting the reference value, the pre Kiho Tadashibu, stored in the storage unit The standard Of relates shake correcting device for correcting the computed reference value before determining said second motion vector.
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. It is the graph which showed the comparison form with respect to this embodiment, (a) is the reference value after correction | amendment in a comparison form, (b) shows the direction of a motion vector. It is the figure which showed the relationship of the error of (omega) 0, and the detection delay of MV_diff. It is a graph which showed the result of having corrected ω0 in a comparative form, (a) shows ω0 and (b) shows MV_diff. It is the graph which showed the result of having corrected ω0 in this embodiment, (a) shows ω0 and (b) shows MV_diff.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing a camera 1 including the shake correction apparatus of the 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, a diaphragm 10, a diaphragm 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, a drive amount calculator 39, a changeover switch 45, and a reference value buffer 46.
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.
The reference value buffer unit 46 stores the past data (reference delay time Δt) of the reference value in the memory. The reference value buffer unit 46 will be described in detail later.
The changeover switch 45 is a switch that can select whether the reference value calculated by the reference value calculation unit 34 is corrected as it is, or whether a past reference value stored in the reference value buffer unit 46 is corrected.
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 MV1) 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. A motion vector MV1 is calculated.

The center bias removal unit 38 subtracts the bias amount calculated by the center bias calculation 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 calculation unit 41. To do.
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 reference value that is stored in the reference value buffer unit 46 and is a predetermined time before.

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 illustrating the reference value calculation unit 34. FIG. 4A illustrates the reference value calculation unit 34 (HPF), and FIG. 4B illustrates 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.

In the present embodiment, when the first motion vector MV1 information is obtained in the center bias removing unit 38, the center bias component is removed and the motion vector information of the ω0 component is converted. Based on this information, ω0comp, which is a correction value for ω0, is calculated.
In this embodiment, ω0comp is added to the past reference value data (before Δt) stored in the reference value buffer unit 46, and this value is replaced with the latest reference value.

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 control period of the optical blur correction is sufficiently early with respect to the update period of the first motion vector MV1, until the first motion vector MV1 is updated, the same calculation process as that of normal image stabilization is performed. 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.

Here, in order to facilitate understanding, first, a comparative example with respect to the present embodiment will be described. FIG. 6A is a graph showing a comparison with this embodiment showing a reference value obtained by correcting the value of V4 ′ in FIG. 4B.
The comparison mode is different from the present embodiment in that the reference value buffer unit 46 is not provided, and past reference value data (before Δt) is not used, ω0_comp is added to the current reference value data, and this value is set. The point is that the process of replacing with the latest reference value is performed.
A dotted line in the figure indicates a reference value when correction is not performed, and a solid line in the figure indicates a reference value corrected according to the comparison mode.

FIG. 6B is a graph showing the direction of MV_diff. For example, when MV_diff 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 MV_diff is confirmed in the positive direction at time t3, the reference value is corrected to negative. 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 MV_diff is confirmed.
When MV_diff is confirmed in the positive direction, the reference value is corrected to a certain amount minus.
Further, when MV_diff is confirmed in the minus direction at times t22 and t25 in the figure, the reference value is corrected to a certain amount plus.

  As described above, also in the comparative form, by correcting the reference value, as shown in FIG. 6A, the correction value can take a value close to the true value.

  However, detection of MV_diff information has a detection delay time: Δt. Due to the error due to this detection delay time, an accurate reference value cannot be obtained.

  FIG. 7 is a diagram showing the relationship between the error of ω0 and the detection delay of MV_diff. Here, a case where the detection delay of MV_diff is 3 frames is shown as an example. The number of detection delay frames is transmitted from the camera CPU 2A of the camera body 1A to the reference value correction amount calculator 35 together with the motion vectors MV1 and MV2.

As shown in the figure, when there is a delay of 3 frames in the detection of MV_diff, the error of ω0 and the detected MV_diff have a relationship as shown in FIG.
For example, the ω0 error at time t2 can be detected by MV_diff at time t6 after the elapse of 3 frames.

FIG. 8 is a graph showing the result of correcting ω0 in the comparative embodiment, where (a) shows ω0 and (b) shows MV_diff. In the comparison mode, for example, MV_diff at the time t7 is calculated, and the ω0 value at the time t7 is corrected.
At time t13, the calculation result of ω0 has converged to a true value, but MV_diff has a value on the plus side. For this reason, here, ω0 is corrected in the negative direction, which increases the error.
In particular, immediately after the sign of the reference value changes (after t2 and after t13), the error may be worsened as shown in FIG.

On the other hand, the delay time of detection of this MV_diff is determined by the calculation performance (frame rate, calculation processing capability) on the body side, so that it is possible to acquire the delay time information.
Therefore, it is possible to obtain a more accurate reference value by correcting the reference value of the angular velocity sensor 12 using the MV_diff information obtained from the body side and the detection delay time information.

  FIG. 9 is a graph showing the result of correcting ω0 in this embodiment, where (a) shows ω0 and (b) shows MV_diff. A case where correction is performed is indicated by a solid line, and a case where correction for a reference value is not performed is indicated by a dotted line.

When there is a delay of 3 frames in the detection of MV_diff, MV_diff at time t0 can be subtracted by subtractor 42 at time t3 (that is, MV_diff at time t3 in FIG. 9).
Therefore, at time t3, the reference value ω0 at time t0 stored in the reference value buffer unit 46 can be subtracted by the subtracting unit 42 at time t3 (ie, MV_diff at time t0, FIG. 9). Correction is performed based on (MV_diff) indicated at time t3.
Then, the reference value ω0 at time t3 is set to a value obtained by correcting the reference value ω0 at time t0 based on MV_diff at time t3.

Similarly, MV_diff at time t3 can be subtracted by the subtracting unit 42 at time t7.
Therefore, at time t7, the reference value ω0 at time t3 stored in the reference value buffer unit 46 can be subtracted by the subtracting unit 42 at time t7 (ie, MV_diff at time t3, FIG. 9). Is corrected based on MV_diff) at time t7.
Then, the reference value ω0 at time t7 is set to a value obtained by correcting the reference value ω0 at time t3 based on MV_diff at time t7.

  Thereafter, the same correction is performed at each time. In the present embodiment, correction is not performed continuously at times t1, t2, and t3, and correction is performed with intervals between t1, t3, and t7.

As described above, this embodiment has the following effects.
(1) The detection of MV_diff information has a detection delay time: Δt (3 frames in this embodiment). However, in the present embodiment, it is possible to obtain a more accurate reference value by correcting the reference value of the angular velocity sensor 12 using the MV_diff information obtained from the body side and the detection delay time information. Become.
(2) In the present embodiment, the center bias component 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.
(3) Since the centering bias process is performed, 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.
(4) Since the changeover switch 45 is provided, whether the reference value calculated by the reference value calculation unit 34 is corrected as it is or whether the past reference value stored in the reference value buffer unit 46 is corrected. Selectable.

(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, 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, 46: reference value buffer unit, 100, 200: blur correction device

Claims (5)

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 storage unit for storing the reference value calculated by the reference value calculation unit;
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;
A driver for driving the thus the blur correction unit before Symbol targets position,
A motion vector calculating unit for calculating a first motion vector of the previous SL object image,
Said first motion vector, by the second motion vector obtained from the control and, where the drive unit is moved toward the shake correction unit in the center of the movable range of the blur correction unit, you correcting the reference value complement Normal part,
With
Before Kiho Tadashibu, among the reference values stored in the storage unit, the shake correcting device for correcting the computed reference value before determining said second motion vector. The shake correction apparatus according to claim 1,
The motion vector is obtained from an image signal obtained by photoelectrically converting the subject image,
Before Kiho Tadashibu among the reference values stored in the storage unit, the shake correcting device for correcting the reference value of time when the image signal is the basis of the motion vector using complement positively was generated . The shake correction apparatus according to claim 2,
Before Kiho Tadashibu is provided in a lens barrel having an optical system for imaging the subject image,
Motion compensation device in front Kiho positive portion or information to correct any of a plurality of the reference value stored in the storage unit, acquires from the camera body to the lens barrel is mounted. The blur correction device according to any one of claims 1 to 3,
Wherein the correction unit is configured for the blur correction unit is moved toward the center of the movable range of the blur correction unit, a bias amount by the target position, wherein the second motion vector removal from the first motion vector A shake correction apparatus for correcting the reference value .   An optical apparatus comprising the shake correction device according to claim 1.

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