JP2015106086A - Tremor correction device and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tremor correction device and optical device that allow for a reference value correction excellent in accuracy.SOLUTION: A tremor correction device 100 according to the present invention comprises: an angular velocity sensor 12 that detects an angular velocity of an optical member 1B; a reference value computation unit 34 that computes a reference value of an output signal of the angular velocity sensor 12; an image pickup element 3 that generates an image signal for each of continuous frames on the basis of input subject image light; a determination unit 45 that determines whether to correct the reference value and determines an amount of correction when correcting the reference value; a reference value correction unit 42 that corrects the reference value on the basis of a motion vector of an image between the frames computed from the image signal on the basis of a determination result of the determination unit 45; a target position computation unit 36 that computes a target position of an optical element 6 to be moved for causing the optical member 1B to perform a tremor correction on the basis of the output signal of the angular velocity sensor 12 and the post-corrected reference value; and an optical element actuation unit 9 that actuates the optical element 6 on the basis of the target position computed by the target position computation unit 36.

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 the motion vector information. In addition, center bias processing is sometimes performed to prevent the blur correction lens from reaching the movable end, but a technique for changing the correction gain of the reference value according to the amount of the center bias has also been proposed. (See Patent Document 1).

Japanese Patent No. 4360147

However, as described above, when the reference value is corrected using the motion vector information, there are the following problems.
The correction of the reference value using the motion vector information is based on the premise that the reference value error is equivalent to the motion vector information. However, when shooting a moving subject (sports, pet, etc.), the motion vector information obtained is mainly subject blur information. In this case, if the reference value correction is performed using the motion vector information, the error may increase. In addition, the motion vector information at the time of macro shooting probably includes a translation blur component. Even in this case, there is a possibility that the error is increased for the same reason.
An object of the present invention is to provide a shake correction apparatus and an optical apparatus capable of correcting a reference value with high accuracy.

The present invention solves the above problems by the following means.
According to a first aspect of the present invention, in the shake correction device for correcting the shake of the optical member, an angular velocity sensor that detects an angular velocity of the optical member, and a reference value calculation unit that calculates a reference value of an output signal of the angular velocity sensor; An image sensor that generates an image signal for each successive frame based on the input subject image light, a determination unit that determines whether or not to correct the reference value, and a correction amount if correction is performed, and the determination unit Based on the determination result, the reference value correction unit for correcting the reference value based on the motion vector of the image between the frames calculated from the image signal, the output signal of the angular velocity sensor and the corrected value Based on the target position calculated by the target position calculation unit, a target position calculation unit that calculates a target position of the optical element to be moved to correct the blur of the optical member based on the reference value It comprises a, an optical element driving unit for driving the optical element, a motion compensation device according to claim.
The invention according to claim 2 is the shake correction apparatus according to claim 1, wherein the determination unit receives imaging information of the optical member and performs the determination based on the received imaging information. In other words, this is a characteristic blur correction device.
According to a third aspect of the present invention, in the blur correction device according to the second aspect, the optical member includes a photographing lens, and the photographing information includes information on whether the photographing magnification is higher than a predetermined value. And the determination unit does not correct the reference value when the photographing magnification is higher than the predetermined value.
The invention according to claim 4 is the shake correction apparatus according to claim 2 or 3, wherein the optical member includes a camera, and the shooting information is a shooting scene that can be selected by the camera, and the determination is made. The blur correction apparatus is characterized in that, based on the information of the shooting scene, whether or not to correct the reference value and, when correcting, determine a correction amount.
The invention according to claim 5 is the shake correction apparatus according to claim 4, wherein the determination unit does not correct the reference value when the shooting scene is in a mode for shooting a moving object. This is a characteristic blur correction device.
The invention according to claim 6 is the shake correction apparatus according to any one of claims 1 to 5, wherein the optical element is moved based on the target position calculated by the target position calculation unit. A center bias calculation unit that adds a center bias component toward the center of the movable range of the optical element, and a center bias removal that calculates a second motion vector obtained by removing the center bias component from the motion vector calculated by the motion vector calculation unit And the reference value correction unit corrects the reference value based on the second motion vector.
A seventh aspect of the present invention is an optical instrument comprising the shake correction apparatus according to any one of the first to sixth aspects.
In addition, the said structure may be improved suitably, and at least one part may substitute for another structure.

  ADVANTAGE OF THE INVENTION According to this invention, the blurring correction apparatus and optical apparatus which can correct | amend a reference value with a sufficient precision can be provided.

It is sectional drawing which shows typically a camera provided with the blurring correction apparatus of embodiment. It is a block diagram of the shake correction apparatus of an embodiment. It is the flowchart which showed the flow of operation | movement of the blurring correction apparatus of 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.

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, a sub mirror 19a, a shutter 20, and an operation member 22. ing.

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. A sub-mirror 19 a is provided behind the mirror 19 and guides subject light to the AF sensor 16.

  The operation member 22 is a member that selects a shooting mode, and the photographer can select a shooting mode according to the shooting scene via the operation member 22. Examples of the shooting mode include a sports mode, a fireworks display mode, a pet mode, and an underwater mode.

  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, an amplification unit 31, 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 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, a target position calculation unit 36 including an integration unit therein, and a center bias calculation unit. 37, a center bias removing unit 38, a drive amount calculating unit 39, a reference value correcting unit 42, and a determining unit 45 for determining whether or not to perform reference value correction.

The angular velocity sensor 12 includes a lens barrel 1B around the X axis (Pitch), around the Y axis (Yaw) (where the X axis is the horizontal axis of the light receiving surface of the image sensor 3 at the normal position of the camera, and the Y axis is This is a sensor such as a vibration gyro that detects the angular velocity of the vertical axis.
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 a reference value (corrected angular velocity 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. Actually, in order to obtain a motion vector with the configuration of FIG. 1, the mirror is raised, a through image (live view) is obtained, and calculation is performed in a state where light (image) reaches the image sensor 3.

The motion vector calculation unit 41 calculates a motion vector (first motion vector) indicating the motion (motion direction, amount of motion) of the image 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. Actually, a motion vector equivalent to camera shake is calculated from the motion of the image.

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 37.

The determination unit 45 determines whether or not to perform reference value correction based on the mode information received from the camera CPU 2A. The mode information is a shooting mode set in the camera 1.
The 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 is pressed, the shake correction apparatus 100 starts computation 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 of angular velocity (value corresponding to zero deg / s) based on the signal after A / D conversion of the output of the angular velocity sensor 12 (step S003). 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 including the LPF 34a), and FIG. 4B shows the LPF 34a of the reference value calculation unit 34. FIG.

  The determination unit 45 determines whether or not to perform reference value correction based on the mode information received from the camera CPU 2A. The reference value correction unit 42 switches execution / non-execution of the angular velocity reference value correction based on the determination result.

For example, when the sports mode that is the moving body photographing mode is set in the camera 1, there is a high possibility that the subject motion blur information is included in the obtained motion vector information. For this reason, it is assumed that the blur correction process is performed only on the angular velocity sensor information (step S004, NO).
Similarly, even when the following mode is set in the camera 1, since it is the moving body shooting mode, the reference value correction using the motion vector information is not performed (step S004, NO).
Fireworks mode,
Pet mode,
Underwater mode,
Aquarium mode etc.

  Not limited to the above, a scene mode in which the motion vector information and the angular velocity reference value error are assumed to be inconsistent, for example, in a vehicle (for example, in a ship, in a train, etc. Etc.), it is preferable to perform blur correction only by the angular velocity information. Further, during macro photography, since the parallel shake component is included in the motion vector information, the shake correction process using only the angular velocity sensor information is also performed in this case (step S004, NO).

In step S004, when the shooting scene mode obtained from the camera 1 is not a predetermined scene in which the motion vector information and the angular velocity reference value error do not match as described above (step S004, YES), the process proceeds to step S005.
If the information on the first motion vector MV1 is updated (S005, YES), the process proceeds to S006, and if not updated (S005, NO), the process proceeds to S007. The description of S004 to S006 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 blur correction lens group 6 is calculated based on the focal length, subject distance, photographing magnification, and blur correction lens characteristic information (S007).
Center bias processing is performed to prevent the blur correction lens group 6 from reaching the movable end (S008).

  There are various methods for the center bias processing, such as a method for setting a bias amount according to target position information and an HPF processing, but the method is not limited here.

The lens drive amount is calculated from the difference between the target position information including the center bias component and the blur correction lens position information (S009).
The blur correction lens group 6 is driven to the target position (S010), and the process returns to S002.

Next, reference value correction (S004 to S006, 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 (S005), the process proceeds to S006. If not updated, the process proceeds to S007.
Since the optical blur correction control cycle is sufficiently early with respect to the MV1 update cycle, the same arithmetic processing as normal image stabilization is performed until the 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 S008 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 * f (1 + 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.

As described above, this embodiment has the following effects.
When shooting a moving subject (sports, pet, etc.), the motion vector information obtained is mainly subject blur information. In this case, if the reference value correction is performed using the motion vector information, the error may increase.
However, in the present embodiment, the determination unit 45 determines whether or not to perform reference value correction based on the mode information received from the camera CPU 2A. The reference value correction unit 42 switches execution / non-execution of the angular velocity reference value correction based on the determination result. Therefore, there is no possibility that the error increases.

(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.

(1) In the present embodiment, the mode of determining whether to correct the reference value according to the shooting mode has been described, but the present invention is not limited to this.
For example, it may be determined whether or not to correct the reference value based on information on whether or not the photographing magnification is higher than a predetermined value. If the photographing magnification is higher than the predetermined value, the reference value is corrected. May not be performed.

(2) In the present embodiment, the mode of determining whether to correct the reference value according to the shooting mode has been described, but the present invention is not limited to this. For example, in the mode of shooting a moving object, the correction amount of the reference value may be changed according to the shooting mode, such as reducing the correction amount of the reference value.

(3) In the present embodiment, the mode of performing blur correction by moving the blur correction lens group has been described, but the present invention is not limited to this. For example, blur correction may be performed by moving the image sensor, or blur correction may be performed by moving the blur correction lens group and the image sensor.

(4) In the present embodiment, the determination unit 45 is. Although an example included in the lens CPU 2B will be described, the present invention is not limited to this, and the determination unit 45 may be included in the camera CPU 2A.

  In addition, although embodiment and a deformation | transformation form can also be used in combination as appropriate, 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, 45: determination unit, 100: blur correction device

Claims (7)

In the shake correction device for correcting the shake of the optical member,
An angular velocity sensor for detecting an angular velocity of the optical member;
A reference value calculation unit for calculating a reference value of the output signal of the angular velocity sensor;
An image sensor that generates an image signal for each successive frame based on the input subject image light;
Whether to correct the reference value, and a determination unit to determine a correction amount when correcting,
A reference value correction unit that corrects the reference value based on a motion vector of an image between the frames calculated from the image signal based on a determination result of the determination unit;
A target position calculation unit that calculates a target position of an optical element that is moved to correct the shake of the optical member based on the output signal of the angular velocity sensor and the corrected reference value;
An optical element driving unit that drives the optical element based on the target position calculated by the target position calculating unit,
A blur correction device characterized by the above. The shake correction apparatus according to claim 1,
The determination unit receives shooting information of the optical member and performs the determination based on the received shooting information;
A characteristic blur correction device. The shake correction apparatus according to claim 2,
The optical member includes a photographic lens,
The shooting information is information on whether the shooting magnification is higher than a predetermined value,
The determination unit does not correct the reference value when the shooting magnification is higher than the predetermined value;
A blur correction device characterized by the above. The shake correction apparatus according to claim 2 or 3,
The optical member includes a camera;
The shooting information is a shooting scene that can be selected by the camera,
The determining unit determines whether or not to correct the reference value based on the information of the shooting scene, and determines a correction amount in the case of correcting;
A blur correction device characterized by the above. The blur correction device according to claim 4,
When the shooting scene is a mode for shooting a moving object,
The determination unit does not correct the reference value;
A blur correction device characterized by the above. The blur correction device according to any one of claims 1 to 5,
Based on the target position calculated by the target position calculation unit, a center bias calculation unit that adds a center bias component that moves the optical element toward the center of the movable range of the optical element;
A center bias removing unit that computes a second motion vector obtained by removing the center bias component from the motion vector computed by the motion vector computing unit,
The reference value correction unit corrects the reference value based on the second motion vector;
A blur correction device characterized by the above.   An optical apparatus comprising the shake correction apparatus according to claim 1.

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