Anti-shake system and image stabilization method

Abstract

The purpose of the present invention is to reduce the time required for an OIS (5) unit to move between frames. An anti-shake system (3) includes an optical image stabilization (OIS) unit (5), a vibration suppressor, and an OIS controller (6). The OIS unit (5) is configured so as to be able to change the position of the optical system. The vibration suppressor is configured to remove or reduce a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system. The OIS controller (6) is configured to execute feedback control for controlling the position of the optical system. The OIS controller (6) is configured to move the optical system to a reference position between the frames based on a signal indicating that the target value of the specific frequency has been removed or reduced.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an anti-shake system and an image stabilization method. Background Art

[0002] Imaging devices having an anti-shake system, such as camcorders and still cameras, are currently known to be generally equipped with an optical image stabilization (OIS) unit configured to optically correct image blur of a captured image caused by camera shake or the like during imaging.

[0003] When the exposure time becomes longer and the amount of movement of the OIS unit increases, such as when shooting a video with a smartphone (imaging device) while walking at night, there may be a situation where the movement of the OIS unit exceeds its movable range and hits the mechanical end, thereby causing the OIS unit to be unable to move. As a result, there is a problem of image quality degradation, such as the occurrence of point light source trailing or image ghosting.

[0004] For this problem, conventional technology discloses returning the OIS unit to the center position during a non-exposure period between video frames and absorbing a deviation in the return amount by electronic image stabilization (EIS) to prevent the OIS unit from hitting the mechanical end. Summary of the invention

[0005] [Problems to be Solved by the Invention]

[0006] When users shoot in dark places, they need a long exposure time. However, when the OIS unit moves between frames, there is a problem that a long exposure time cannot be obtained because the movement of the OIS unit takes time. The time required for the movement includes the time for the OIS unit to move, and the time for the vibration of the OIS unit after the movement and the AF (Automatic Focus) unit mounted on the OIS unit to be sufficiently attenuated.

[0007] An object of the present disclosure is to reduce the time required for the OIS unit to move between frames.

[0008] [Solution to the problem]

[0009] According to one aspect of an embodiment, an anti-shake system includes an optical image stabilization (OIS) unit, a vibration suppressor, and an OIS controller. The OIS unit is configured to be able to change the position of an optical system. The vibration suppressor is configured to remove or reduce a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system. The OIS controller is configured to perform feedback control to control the position of the optical system. The OIS controller is configured to move the optical system to a reference position between frames based on a signal indicating that the target value of the specific frequency has been removed or reduced.

[0010] According to another aspect of the embodiment, an image stabilization method includes: in optical image stabilization (OIS) that changes the position of an optical system, removing or reducing a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system; performing feedback control that controls the position of the optical system; and moving the optical system to the reference position between frames based on the signal indicating the target value from which the specific frequency has been removed or reduced.

[0011] [Effects of the Invention]

[0012] According to an embodiment of the present disclosure, the time required for an OIS unit to move between frames can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram showing a configuration example of an imaging device equipped with an anti-shake system according to an embodiment;

[0014] Figure 2 is a schematic diagram illustrating the movement process of the OIS unit between frames;

[0015] Figure 3 is a schematic diagram showing a configuration example of an anti-shake system according to an embodiment;

[0016] Figure 4 is a schematic diagram illustrating the convergence of vibration of an OIS unit with movement; and

[0017] Figure 5 is a schematic diagram illustrating the convergence of the vibration of the OIS unit with movement. DETAILED DESCRIPTION

[0018] Hereinafter, an anti-shake system, an imaging device, and an image stabilization method according to an embodiment will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment.

[0019] In the description of the present embodiment, components having the same or substantially the same functions as components previously described in the previous drawings have the same reference numerals, and their descriptions may be appropriately omitted. In addition, even if the same or substantially the same parts are shown, the size and proportion of the parts may be different from one drawing to another. In addition, from the perspective of ensuring the visibility of the drawings, for example, reference numerals may be assigned only to the main components used to describe each drawing, and components having the same or substantially the same functions as components previously described in the previous drawings may not have reference numerals.

[0020] It should be noted that in the description of this embodiment, "a, b" is added at the end of the reference numerals to distinguish different components having the same or substantially the same functions. In addition, in the description of this embodiment, adding "a, b" at the end of the reference numerals is omitted, and multiple components having the same or substantially the same functions can be collectively referred to.

[0021] Imaging devices having an anti-shake system, such as camcorders and still cameras, are currently known to be generally equipped with an optical image stabilization (OIS) unit configured to optically correct image blur of a captured image caused by camera shake or the like during imaging.

[0022] When the exposure time becomes longer and the amount of movement of the OIS unit increases, such as when shooting a video with a smartphone (imaging device) while walking at night, there may be a situation where the movement of the OIS unit exceeds its movable range and hits the mechanical end, thereby causing the OIS unit to be unable to move. As a result, there is a problem of image quality degradation, such as the occurrence of point light source trailing or image ghosting.

[0023] With regard to this problem, conventional technology discloses returning the OIS unit to a center position during a non-exposure period between video frames, and absorbing a deviation in the return amount by electronic image stabilization (EIS) to prevent the OIS unit from hitting a mechanical end.

[0024] When users shoot in dark places, they need a long exposure time. However, when the OIS unit moves between frames, there is a problem that a long exposure time cannot be obtained because the movement of the OIS unit takes time. The time required for the movement includes the time for the OIS unit to move and the time until the vibration of the OIS unit after the movement and the AF unit mounted on the OIS unit is sufficiently attenuated.

[0025] In recent years, as image sensor performance has improved, the rolling shutter time is being shortened. In this article, the non-exposure time between frames includes the rolling shutter time for sequential reading from each row of the image sensor and the time required for the OIS unit to move.

[0026] Therefore, the following embodiments show an anti-shake system, an imaging device, and an image stabilization method, which can reduce the time required for the OIS unit to move between frames. Optionally, the following embodiments also show an anti-shake system and an imaging device equipped with the anti-shake system, which is configured to be able to perform control of moving the OIS unit at high speed while suppressing vibration of the AF unit mounted on the OIS unit (image stabilization method).

[0027] As an example, the imaging device equipped with the anti-shake system according to the embodiment is used in a state where the user holds the imaging device. While holding the imaging device, the user can move the imaging device or change its direction. As another example, the imaging device is used in a state where the imaging device is mounted on various movable objects such as bicycles, motorcycles, and cars.

[0028] Figure 1 1 is a schematic diagram showing a configuration example of an imaging device 1 equipped with an anti-shake system 3 according to an embodiment. The imaging device 1 is configured to image a shooting scene to generate image data. Figure 1 As shown, the imaging device 1 includes a lens barrel assembly 11 , an image sensor 13 , an AF unit 7 , and an AF controller 8 .

[0029] The lens barrel assembly 11 includes an optical system. The optical system includes optical elements configured to form an image of a light beam from a photographic subject on an imaging surface of an image sensor 13. The optical system includes at least one imaging lens 11a. The optical system can obtain the desired imaging performance by at least one optical element having optical power, and thus can be composed of a composite lens including at least one single lens, or can be composed of a combination of a lens system and a reflection system.

[0030] It should be noted that in the present embodiment, it is assumed that the position of the imaging lens 11a in the lens barrel assembly 11 is fixed. In other words, it is assumed that the imaging device 1 in the present embodiment is configured to be able to change its focal position by performing an expansion operation or a contraction operation of the lens barrel assembly 11 by the AF unit 7. More specifically, the imaging device 1 is configured to be able to change its focal position by changing the position of the lens barrel assembly 11 relative to the image sensor 13 in the optical axis direction of the imaging lens 11a (indicated by the dotted line). Herein, the position change of the lens barrel assembly 11 relative to the image sensor 13 in the optical axis direction can be expressed as the position change of the imaging lens 11a (focusing lens) relative to the image sensor 13 in the optical axis direction. Figure 1 In the example shown, the optical axis direction of the optical system (indicated by a dotted line) is the Z direction.

[0031] Herein, "being able to change the focal position" means that the image formed on the imaging surface of the image sensor 13 can be smaller than the diameter of the circle of confusion allowed for each of at least two object points located at different positions in the optical axis direction. For example, the allowable diameter of the circle of confusion is defined based on the pixel pitch of the image sensor 13 or the imaging performance of the optical system. In other words, the imaging device 1 is configured to be able to focus on or blur (bokeh) any photographic object.

[0032] It should be noted that at least one imaging lens 11a may be configured to be movable in the optical axis direction relative to the lens barrel assembly 11. In other words, the imaging device 1 is configured to be able to change its focal position by changing the position of at least one imaging lens 11a (focusing lens) relative to the lens barrel assembly 11 in the optical axis direction.

[0033] It should be noted that the lens barrel assembly 11 may include at least one zoom lens. In this case, the imaging device 1 may be configured to be able to change the zoom ratio by moving the zoom lens or the lens barrel assembly 11 in the optical axis direction.

[0034] The image sensor 13 is arranged on the optical axis of the optical system of the lens barrel assembly 11. The image sensor 13 is arranged at a position where the optical system forms an image of a light beam from a photographic object. The image sensor 13 can appropriately adopt a solid-state imaging device such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor).

[0035] The image sensor 13 is configured to generate an image signal corresponding to a light beam from a photographic object. It should be noted that the imaging device 1 also includes an analog processing circuit, an A / D converter, and an image processing circuit, which are not shown, at the rear of the image sensor 13. The analog processing circuit is configured to perform analog processing, such as amplification processing, on the image signal read from the image sensor 13. The A / D converter is configured to convert the image signal output by the analog processing circuit into image data in a digital format. The image processing circuit is configured to perform various image processing required to display and record images associated with the image data in a digital format. These image processing include, for example, optical black (OB) subtraction processing, white balance (WB) correction processing, demosaicing processing, color conversion processing, gamma conversion processing, noise reduction processing, enlargement / reduction processing, and compression processing.

[0036] It should be noted that the imaging device 1 may be configured to be able to move the imaging surface of the image sensor 13 in the optical axis direction of the optical system without being limited to the image side focal position and the object side focal position of the optical system. In other words, the imaging device 1 may be configured to be able to change its focal position by changing the optical axis direction position of at least one of the image side focal position, the object side focal position, and the imaging surface.

[0037] It should be noted that when the image sensor 13 is configured to be movable, the peak frequency in the closed-loop characteristic of the feedback control of the OIS unit to be described below can be determined according to the position of the image sensor 13. In addition, the peak frequency can also be determined according to the position of the lens barrel assembly 11. In these cases, the notch filter 4 to be described below can be configured to remove or reduce multiple frequencies, or can be configured to include multiple switchable notch filters with different removal or reduction frequencies.

[0038] The AF unit 7 is configured to adjust the focus position of the imaging device 1. In addition, the AF unit 7 is also configured to measure the current position of the barrel assembly 11 (focusing lens) and output the measurement result. Optionally, the AF unit 7 includes an AF / OIS magnet 33, a lens holder 71, an AF coil (drive coil) 73, an AF spring 75, an AF Hall element 77, and an AF controller 8.

[0039] The AF unit 7 is supported by an AF spring 75 to be attached to the movable portion of the OIS unit 5. Optionally, the AF spring 75 is supported in the optical axis direction ( Figure 1 The lens holder 71 is movably supported in the Z direction (in the middle). The lens holder 71 supports the lens barrel assembly 11. Figure 1 In the example of FIG. 5 , one end of the AF spring 75 is fixed to the OIS housing 51, and the other end is fixed to the lens holder 71. In addition, the lens holder 71 is fixed to the lens barrel assembly 11 and the AF coil 73. As described above, the optical system of the lens barrel assembly 11 is movably supported by the OIS unit 5 in the optical axis direction.

[0040] The AF springs 75 on the Z+ side and the Z- side apply force to the lens holder 71 so that the lens holder moves in the Z- direction and the Z+ direction respectively. When the lens barrel assembly 11 is located at the reference position in the optical axis direction, the biasing forces applied by the AF springs 75 on the Z+ side and the Z- side to the lens holder 71 are balanced. Here, the AF spring 75 is an example of a flexible member. The flexible member can be a spring or an elastic body such as rubber.

[0041] The AF / OIS magnet 33 is disposed in a direction orthogonal to the optical axis direction of the lens barrel assembly 11 ( Figure 1 The position (in the X direction) facing the AF coil 73 Figure 1The AF / OIS magnet 33 has the following configuration: a magnet 33a with a south pole and a magnet 33b with a north pole are arranged in the moving direction of the lens barrel assembly 11, that is, in the direction of the optical axis ( Figure 1 The AF coil 73 and the AF Hall element 77 are arranged on both sides of the lens holder 71 facing the AF / OIS magnet 33 (Z direction). Figure 1 Alternatively, in a state where the lens barrel assembly 11 is located at the reference position, the AF / OIS magnet 33 and the AF coil 73 are arranged so that the middle position between the magnets 33a and 33b arranged along the optical axis direction becomes the middle position of the AF coil 73. For example, the AF Hall element 77 is provided inside the AF coil 73.

[0042] It should be noted that the AF / OIS magnet 33 may also be disposed in another direction orthogonal to the optical axis direction of the lens barrel assembly 11 ( Figure 1 The position (in the Y direction) facing the AF coil 73 Figure 1 At the Y+ side and Y- side).

[0043] Note that, in the imaging device 1 according to the present embodiment, the AF / OIS magnet 33 is shared by the OIS unit 5 and the AF unit 7. The relationship between the AF / OIS magnet 33 and the OIS unit 5 will be described below.

[0044] As an example, the AF / OIS magnet 33 and the AF coil 73 constitute a lens driving unit. The lens driving unit is configured to move the lens barrel assembly 11 in the optical axis direction according to a control signal from the AF controller 8. Optionally, the AF coil 73 generates a magnetic field according to a control signal (current) from the AF controller 8. The AF / OIS magnet 33 generates a driving force in the optical axis direction according to the magnetic field generated by the AF coil 73.

[0045] As an example, the AF / OIS magnet 33 and the AF Hall element 77 constitute a focus lens position detector. The focus lens position detector is configured to output a detection signal corresponding to the current position of the lens barrel assembly 11. Optionally, the AF Hall element 77 is configured to detect the magnetic field or the change of the magnetic field generated by the AF / OIS magnet 33, and output a detection signal according to the detected magnetic field strength or the change amount.

[0046] The AF controller 8 controls the various components of the AF unit 7. The AF controller 30 includes a processor and a memory as hardware resources. The processor may appropriately adopt various processors, such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programmable Gate Array). In addition, the memory may appropriately adopt various memories, such as a ROM (Read Only Memory), a flash memory, and a RAM (Random Access Memory). It should be noted that the AF controller 8 may adopt a microcomputer. As an example, Figure 1 As shown, the AF controller 8 is disposed in the lens holder 71 .

[0047] The AF controller 8 is configured to perform an automatic focus adjustment (AF) process for controlling the driving of the AF unit 7 based on focus information acquired from image data, etc. Optionally, the AF controller 8 is configured to control the position of the lens barrel assembly 11 in the optical axis direction through feedback control based on the current position and target position of the lens barrel assembly 11.

[0048] As an example, the AF controller 8 is configured to obtain focus information based on image data, etc. The focus information is, for example, an AF evaluation value (contrast value) calculated based on the image data. In addition, when the image sensor 13 is configured with focus detection pixels, the focus information can be a defocus amount calculated based on the output of the focus detection pixels. As an example, the AF controller 8 is configured to calculate the target position of the lens barrel assembly 11 based on the focus information. As an example, through feedback control based on the current position and the target position of the lens barrel assembly 11, the AF controller 8 is configured to output a control signal (current) for moving the lens barrel assembly 11 from the current position to the target position to the AF coil 73.

[0049] like Figure 1 As shown, the anti-shake system 3 includes an AF / OIS housing 31 , an OIS unit 5 and an OIS controller 6 .

[0050] A portion of the AF / OIS housing 31 is configured to be able to transmit light including a wavelength that can be detected by the image sensor 13. This portion is oriented toward the moving area 905 (see Figure 2), that is, the portion corresponding to the moving area 905. As an example, the portion corresponding to the moving area 905 in the AF / OIS housing 31 may not be provided with anything. As an example, the portion corresponding to the moving area 905 in the AF / OIS housing 31 may be provided with an optical window made of resin, glass, etc.

[0051] The OIS unit 5 is configured to be able to change the position of the optical system of the lens barrel assembly 11 relative to the image sensor 13. The OIS unit 5 implements optical image stabilization (OIS) according to the control of the OIS controller 6. Figure 1 As shown, the OIS unit 5 includes an OIS housing 51 , an OIS base 53 , an OIS coil (driving coil) 55 , an OIS spring 57 , and an OIS Hall element 59 .

[0052] The OIS unit 5 includes a movable part and a fixed part. For example, the OIS housing 51 and the various components held by the OIS housing 51 constitute the movable part of the OIS unit 5. For example, the OIS base 53 and the various components held by the OIS base 53 constitute the fixed part. The movable part of the OIS unit 5 is attached to the fixed part so as to be movable relative to the fixed part in at least one direction different from the optical axis direction (Z direction). Here, at least one direction different from the optical axis direction is, for example, at least one of the two directions orthogonal to the optical axis direction. In the present embodiment, "orthogonal" includes substantially orthogonal, and is not limited to strictly orthogonal. In Figure 1 In the example of , the movable part of the OIS unit 5 is attached to the fixed part so as to move relative to the fixed part in a direction orthogonal to the optical axis direction, that is, in the X direction and the Y direction. In other words, the fixed part of the OIS unit 5 movably supports the movable part in the X direction and the Y direction. It should be noted that the fixed part of the OIS unit 5 is not limited to movably supporting the movable part in the X direction and the Y direction, but may also movably support the movable part in the Z direction.

[0053] The movable part of the OIS unit 5 is supported by an OIS spring 57 to be attached to the fixed part of the OIS unit. Optionally, the OIS spring 57 is in a plane orthogonal to the optical axis ( Figure 1 The fixed part is movably supported in the biaxial directions of the X and Y directions in the Figure 1 In the example, one end of the OIS spring 57 is fixed to the OIS housing 51 , and the other end is fixed to the OIS base 53 .

[0054] The OIS springs 57 on the X+ side and the X- side apply force to the OIS housing 51 so that the OIS housing 51 moves in the X- direction and the X+ direction, respectively. In addition, the OIS springs 57 on the Y+ side and the Y- side apply force to the OIS housing 51 so that the OIS housing 51 moves in the Y- direction and the Y+ direction, respectively. When the OIS housing 51 is located at a reference position of the XY plane, the bias forces applied to the OIS housing 51 by the OIS springs 57 on the X+ side and the X- side are balanced. In addition, when the OIS housing 51 is located at a reference position of the XY plane, the bias forces applied to the OIS housing 51 by the OIS springs 57 on the Y+ side and the Y- side are also balanced. Here, the OIS spring 57 is an example of a flexible component. The flexible component can be a spring or an elastomer such as rubber.

[0055] The reference position of the OIS housing 51 is, for example, the middle position of the AF / OIS housing 31 in the X direction and the Y direction. Figure 1 In the example shown, the reference position of the OIS housing 51 in the X direction is the middle position of the movable range 903 in the X direction. It should be noted that, for example, when the OIS housing 51 is located at the reference position, the gap 901 between the AF / OIS housing 31 and the OIS housing 51 is equal in size in the X direction and the Y direction. In addition, for example, when the OIS housing 51 is located at the reference position, the optical axis of the lens barrel assembly 11 passes through the center of the imaging surface of the image sensor 13. In other words, when the OIS housing 51 is located at the reference position, the imaging lens 11a is located at the center of the moving area 905 in the XY plane (see Figure 2 ). It should be noted that the reference position of the OIS housing 51 may be different from the middle position of the AF / OIS housing 31 in the X direction and the Y direction, or may be different between any two frames. For example, in a frame where the smartphone (imaging device) is moving in one direction, the reference position may be changed to a position closer to the moving direction than the middle position.

[0056] A portion of the OIS housing 51 is configured to be able to transmit light including a wavelength that can be detected by the image sensor 13. This portion corresponds to the moving area 905. As an example, the portion of the OIS housing 51 corresponding to the moving area 905 may not be provided with anything. As an example, the portion of the OIS housing 51 corresponding to the moving area 905 may be provided with an optical window made of a material such as resin, glass, etc.

[0057] The AF / OIS magnet 33 is disposed in a direction orthogonal to the optical axis direction of the lens barrel assembly 11 ( Figure 1The AF / OIS magnet 33 is at a position facing the OIS coil 55 on the X direction and the Y direction in the OIS housing 51. The AF / OIS magnet 33 has the following configuration: a magnet 33a with a south pole and a magnet 33b with a north pole are arranged in the moving direction of the OIS housing 51, that is, the X direction or the Y direction, and are located on the side facing the OIS coil 55 and the OIS Hall element 59. As an example, the AF / OIS magnet 33 arranged on the X+ side and the X- side of the OIS housing 51 has the following configuration: the magnets 33a and 33b are arranged in the X direction. As an example, the AF / OIS magnet 33 arranged on the Y+ side and the Y- side of the OIS housing 51 has the following configuration: the magnets 33a and 33b are arranged in the Y direction. The OIS coil 55 and the OIS Hall element 59 are arranged in a direction ( Figure 1 The X direction and the Y direction in FIG. 1 ) are located on the side of the OIS base 53 facing the AF / OIS magnet 33 ( Figure 1 Alternatively, in a state where the OIS housing 51 is in the reference position, the AF / OIS magnet 33 and the OIS coil 55 are arranged so that the middle position between the magnets 33a and 33b arranged in the X direction or the Y direction becomes the middle position of the corresponding OIS coil 55. For example, the OIS Hall element 59 is provided inside the OIS coil 55.

[0058] As an example, the AF / OIS magnet 33 and the OIS coil 55 constitute an OIS driving unit. The OIS driving unit is configured to move the movable part of the OIS unit 5 in the X direction and / or the Y direction according to the control signal from the OIS controller 6. Optionally, the OIS coil 55 generates a magnetic field according to the control signal (current) from the OIS controller 6. The AF / OIS magnet 33 generates a driving force in the X direction and / or the Y direction according to the magnetic field generated by the OIS coil 55.

[0059] It should be noted that the OIS driving unit of the OIS unit 5 and / or the lens driving unit of the AF unit 7 can be implemented by other actuators such as a shape memory alloy (SMA) actuator, which is configured to generate a driving force by sending an electric current to the shape memory alloy to heat it, and is not limited to the case where it is composed of a voice coil motor (VCM) that uses a magnet and a coil to generate a driving force according to an electromagnetic force.

[0060] As an example, the AF / OIS magnet 33 and the OIS Hall element 59 constitute a posture detector. The posture detector is configured to output a detection signal corresponding to the current position of the OIS housing 51 (the movable part of the OIS unit 5). Optionally, the OIS Hall element 59 is configured to detect the magnetic field or the change of the magnetic field generated by the AF / OIS magnet 33, and output a detection signal according to the detected magnetic field strength or the amount of change.

[0061] The fixed part of the OIS unit 5 includes an acceleration sensor and a gyro sensor in addition to the above-mentioned image sensor 13, analog processing circuit, A / D converter, image processing circuit, OIS coil 55, OIS spring 57 and OIS Hall element 59. These components are mounted on, for example, the OIS base 53. The acceleration sensor and the gyro sensor are examples of sensors configured to detect a shake applied to the fixed part.

[0062] The OIS controller 6 is configured to control each component of the OIS unit 5. The OIS controller 6 includes a processor and a memory as hardware resources. The processor can appropriately adopt various processors such as a CPU, a DSP, an ASIC, and an FPGA. In addition, the memory can appropriately adopt various memories such as a ROM, a flash memory, and a RAM. It should be noted that the OIS controller 6 can adopt a microcomputer. As an example, Figure 1 As shown, the OIS controller 6 is provided on an OIS base 53 (fixed portion).

[0063] The OIS controller 6 is configured to perform feedback control of controlling the position (position in the X direction and the Y direction) of the optical system of the lens barrel assembly 11, for example, based on the blur amount. Alternatively, the OIS controller 6 is configured to control the position of the movable part in the XY plane through feedback control based on the current posture and target posture of the movable part of the OIS unit 5, and perform a correction process of correcting image jitter of a captured image generated accompanying vibration generated in the imaging device 1.

[0064] As an example, the OIS controller 6 is configured to calculate the target posture of the OIS unit 5 based on the detection signal from the acceleration sensor and / or the gyro sensor. As an example, based on the current posture and the target posture of the OIS housing 51, the OIS controller 6 is configured to output a control signal (current) to the OIS coil 55 to move the OIS housing 51 from the current posture to the target posture. It should be noted that the target posture and the current posture of the OIS unit 5 can be respectively expressed as the target position and the current position of the OIS housing 51 in the moving direction (X direction and Y direction).

[0065] Figure 2 Schematic diagram for explaining the movement process of the OIS unit 5 between frames. Figure 2 As described above, during the exposure period T1 of frame 1, the OIS housing 51 is stabilized within the movable range 903 (see FIG. Figure 1 ). At this time, if Figure 2 As shown, in the exposure period T1 of the frame 1, the imaging lens 11a mounted on the movable portion of the OIS unit 5 moves within the moving area 905 according to image stabilization.

[0066] In the case of shooting with a long exposure time, such as shooting in a dark place, the amount of movement of the imaging lens 11a in the exposure period T1 of each frame is large. In other words, in the case of shooting with a long exposure time, when exposure is started in a state where the imaging lens 11a is located at the edge portion of the moving area 905, for example, the OIS housing 51 hits the AF / OIS housing 31 (mechanical end), and thus OIS may not be performed.

[0067] Therefore, the OIS controller 6 is configured to move the optical system of the lens barrel assembly 11 to the reference position between frames (non-exposure period) based on a signal indicating that the target value of the specific frequency has been removed or reduced. In other words, the OIS controller 6 is configured to perform a movement process of moving the movable part to the reference position between frames while suppressing the vibration of the AF unit 7 mounted on the movable part of the OIS unit 5. For example, when the reading of the last line of each frame is completed, that is, when the non-exposure period T2 starts, the OIS controller 6 performs the movement process.

[0068] It should be noted that the OIS controller 6 can be configured to perform the movement process between the next frames only when the OIS housing 51 contacts the mechanical end, when the gap 901 between the AF / OIS housing 31 and the OIS housing 51 is not greater than a predetermined threshold, or when the end of the moving area 905 is detected from the captured image.

[0069] like Figure 2 As shown, the non-exposure period T2 is the time after the rolling shutter time T3 is removed from the inter-frame period. Therefore, the movement process of the movable part of the OIS unit 5 returning to the reference position can be performed within the non-exposure period T2 within the inter-frame period. Therefore, it is required to shoot with a long exposure time to reduce the time required for the movement process and shorten the non-exposure period T2.

[0070] The time required for the movement process here includes the movement time of moving the movable part of the OIS unit 5 by the control of the OIS controller 6. In addition, the time required for the movement process also includes a damping time during which the vibration generated on the movable part of the OIS unit 5 and the AF unit 7 due to the movement is damped to a predetermined range.

[0071] As an example, the OIS controller 6 is configured to output a control signal (current) to the OIS coil 55 to move the OIS housing 51 from a current posture to a target posture through feedback control with a reference position as a target position during movement.

[0072] The method of setting the target value of the OIS unit 5 in the feedback control includes a method of setting the target value in a step-like manner and a method of setting the target value in a ramp-like manner, etc. For example, the method of setting the target value in a ramp-like manner has higher stability and shorter decay time, but has a longer movement time because the moving speed of the movable part of the OIS unit 5 is lower. For example, the method of setting the target value in a step-like manner has a shorter movement time, but has lower stability and longer decay time because the moving speed of the movable part of the OIS unit 5 is higher. In addition, for example, in a method of dividing and setting the target value into a plurality of steps, as the number of divisions (number of steps) increases, the movement time also becomes longer.

[0073] Therefore, the anti-shake system 3 according to the present embodiment includes a vibration suppressor configured to set a target value of one step in a step-like manner to increase the moving speed and reduce the decay time. The vibration suppressor is configured to remove or reduce a signal having a specific frequency from a target value signal indicating a reference position of the optical system of the lens barrel assembly 11. In other words, the vibration suppressor performs a filtering process to remove or reduce a signal having a specific frequency from an input signal 907 indicating a step-like target value to be input to the OIS controller 6. It should be noted that the vibration suppressor may also set a plurality of step-like target values ​​in a step-like manner.

[0074] Figure 3 : is a schematic diagram showing a configuration example of the anti-shake system 3 according to the embodiment. Figure 3 FIG. 4 shows a notch filter 4 as a vibration suppressor in the embodiment. Figure 3 As shown in the block diagram of FIG. 5 , the notch filter 4 is provided before the OIS controller 6. In other words, the notch filter 4 is provided before the control loop (feedback loop) of the OIS unit 5 forming a closed loop.

[0075] The notch filter 4 is a filter for removing or reducing a signal having a specific frequency and may also be referred to as a band elimination filter BEF (band elimination filter), BRF (band rejection filter) or BSF (band stop filter).

[0076] As described above, the AF unit 7 is supported by the OIS unit 5 through the AF spring 75. Therefore, the movement of the movable part of the OIS unit 5 is different from the movement of the AF unit 7. For example, when the movable part of the OIS unit 5 reciprocates in the X direction or the Y direction, the amplitude and phase of the movement of the AF unit 7 are different from the amplitude and phase of the movable part of the OIS unit 5. In other words, the optical system of the lens barrel assembly 11 can move in the optical axis direction in the AF unit 7, and can also move in a direction different from the optical axis direction according to the deformation of the AF spring 75 that occurs with the movement of the movable part of the OIS unit 5. Based on these factors, due to the nested structure of the OIS unit 5 and the AF unit 7, it is difficult for the control loop of the OIS unit 5 to suppress vibrations having a specific frequency. Alternatively, in the gain diagram of the control loop of the OIS unit 5, a specific frequency (peak frequency) that takes a positive value is likely to cause vibration to remain.

[0077] Therefore, the notch filter 4 is configured to remove or reduce the peak frequency in the closed loop characteristic. This can speed up the vibration attenuation in the control loop (feedback loop) of the OIS unit 5 and shorten the time of the moving process.

[0078] Figure 4 and Figure 5 It is a schematic diagram for explaining the convergence of the vibration of the OIS unit 5 along with the movement. Figure 4 The behaviors of the OIS unit 5 (solid line) and the AF unit 7 (dashed line) are shown when the notch filter 4 as a vibration suppressor is not provided, unlike the anti-shake system 3 according to the present embodiment. Figure 5 1 shows the behavior of the OIS unit 5 (solid line) and the AF unit 7 (dashed line) in the anti-shake system 3 provided with the notch filter 4 according to the embodiment. Figure 4 and Figure 5 In the graph of , the vertical axis represents the X-direction position [μm] and the horizontal axis represents the time [s], respectively.

[0079] It should be noted that Figure 4 and Figure 5 The behavior of the OIS unit 5 and the AF unit 7 when the target value is changed in one step in the X direction in a step-like manner is shown. Figure 5 A case where a notch filter 4 is provided is shown, and the notch filter 4 is configured to remove or reduce a signal having a specific frequency of 200 Hz according to a peak frequency of a closed-loop characteristic.

[0080] like Figure 4 As shown, when the notch filter 4 is not provided, for example, Figure 4 At the time point indicated by the middle arrow, the vibration of the OIS unit 5 and the AF unit 7 is not sufficiently attenuated.

[0081] On the other hand, in the case of the anti-shake system 3 provided with the notch filter 4 according to the present embodiment, for example, Figure 5 At the time point indicated by the middle arrow, the vibration amplitude of the OIS unit 5 and the AF unit 7 is approximately the same as that at the same time point when the notch filter 4 is not provided ( Figure 4 The vibration amplitude is half of the time point indicated by the arrow in the middle.

[0082] As described above, according to the image stabilization method of the present embodiment, the anti-shake system 3 for realizing image stabilization, and the imaging device 1 provided with the anti-shake system 3, it is possible to accelerate the attenuation of vibrations generated by the OIS unit 5 and the AF unit 7 during the movement process. In other words, according to the present embodiment, it is possible to reduce the time taken for the movement process between frames. Therefore, even when shooting with a long exposure time, such as shooting in a dark place, OIS can be appropriately performed.

[0083] In addition, the vibration suppressor is configured to remove or reduce the peak frequency according to the control loop of the OIS unit 5 that supports the AF unit 7 through the AF spring 75. Therefore, it is not necessary to detect the position of the AF unit 7 in the moving direction of the movable part of the OIS unit 5. Alternatively, the AF unit 7 may include a focus lens position detector configured to detect the position of the lens barrel assembly 11 in the optical axis direction (Z direction), and thus it is not necessary to provide a sensor for detecting the position in the X direction and the Y direction to detect the vibration convergence.

[0084] It should be noted that since the OIS unit 5 can move at high speed between frames, the image stabilization method according to the present embodiment, the anti-shake system 3 for realizing image stabilization, and the imaging device 1 provided with the anti-shake system 3 can be applied to moving images and continuous shooting, as well as image synthesis after continuous shooting (HDR, night scene multi-shot, etc.).

[0085] It should be noted that the vibration suppressor may be configured to be able to switch the operation of removing or reducing the peak frequency between the exposure period and the inter-frame period. For example, the vibration suppressor is configured to weaken the degree of removal or reduction of the peak frequency during the exposure period compared to the inter-frame period. For example, the vibration suppressor is configured not to remove or reduce the peak frequency during the exposure period. It should be noted that this switching can be achieved by switching multiple notch filters 4 with different degrees of removal or reduction, by switching the number of steps of the notch filter 4, or by switching the use / non-use of the notch filter 4.

[0086] It should be noted that the vibration suppressor may be configured as a part of the OIS controller 6. In addition, the vibration suppressor may also be implemented by firmware (program) processing in the OIS controller 6.

[0087] It should be noted that the processing performed by the circuits behind the image sensor 13, the OIS controller 6 and the AF controller 8 can be implemented as a function of the OIS controller 6, which is implemented by the processor executing a program loaded into the memory, or it can also be implemented as a dedicated circuit.

[0088] It should be noted that at least two of the components of the circuit at the rear of the image sensor 13, the OIS controller 6, and the AF controller 8 may be implemented by one circuit. In addition, at least one of the components of the circuit at the rear of the image sensor 13, the OIS controller 6, and the AF controller 8 may be implemented by combining two or more circuits.

[0089] It should be noted that the image stabilization according to the present embodiment may be implemented by an electronic device including the imaging device 1 and a circuit board (not shown). The circuit board is configured to supply power to the imaging device 1. The circuit board may be a component of the imaging device 1.

[0090] It should be noted that part or all of the processing performed by the imaging device 1 and / or the anti-shake system 3 according to the present embodiment may be realized by software.

[0091] The program executed by the imaging device 1 and / or the anti-shake system 3 according to the present embodiment is recorded in a file in an installable format or an executable format and is set in a flash memory (semiconductor memory) such as a USB (Universal Serial Bus) memory and an SSD (Solid State Drive) and a computer-readable recording medium such as an HDD (Hard Disk Drive).

[0092] Furthermore, the program executed by the imaging device 1 and / or the anti-shake system 3 according to the present embodiment may be configured to be provided by being stored on a computer connected to a network such as the Internet and downloaded through the network. Furthermore, the program executed by the imaging device 1 and / or the anti-shake system 3 according to the present embodiment may also be configured to be provided or distributed through a network such as the Internet.

[0093] Furthermore, the program executed by the imaging device 1 and / or the anti-shake system 3 according to the present embodiment may be configured to be embedded in a ROM or the like in advance and provided.

[0094] According to at least one of the embodiments described above, the time required for an OIS unit to move between frames can be reduced.

[0095] Although certain embodiments have been described, these embodiments are presented only as examples and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes may be made to the forms of the embodiments described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of the invention.

[0096] (Supplementary explanation)

[0097] (1) An anti-shake system comprising:

[0098] an optical image stabilization (OIS) unit configured to be capable of changing a position of the optical system;

[0099] a vibration suppressor configured to remove or reduce a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system; and

[0100] The OIS controller is configured to perform feedback control to control the position of the optical system and to move the optical system to a reference position between frames based on a signal indicating a target value by which a specific frequency has been removed or reduced.

[0101] (2) In the anti-shake system according to (1), the vibration suppressor includes a notch filter.

[0102] (3) In the imaging device according to (1) or (2), the vibration suppressor is configured to reduce the degree of removing or reducing the signal having a specific frequency from the signal indicating the target value during the exposure period compared to the period between frames.

[0103] (4) In the anti-shake system according to any one of (1) to (3), the specific frequency includes a peak frequency in a closed-loop characteristic of the feedback control.

[0104] (5) In the anti-shake system according to any one of (1) to (4), the movable portion of the OIS unit is movable in at least one direction different from the optical axis direction of the optical system, and

[0105] The movable portion supports the optical system that moves in the optical axis direction of the optical system via the flexible member so as to move in the moving direction of the movable portion.

[0106] (6) In the anti-shake system according to (5), the at least one direction different from the optical axis direction of the optical system includes at least one of two directions orthogonal to the optical axis direction.

[0107] (7) In the anti-shake system according to any one of (1) to (6), the optical axis of the optical system at the reference position passes through the center of the moving area of ​​the optical system.

[0108] (8) In the anti-shake system according to any one of (1) to (7), the OIS controller is configured to move the optical system to the reference position in one step.

[0109] (9) An imaging device is provided with the anti-shake system according to any one of (1) to (8).

[0110] (10) The imaging device according to (9) further includes:

[0111] an image sensor configured to generate an image signal according to a light beam capturing a scene; and

[0112] An optical system configured to form an image of a light beam from a subject on an imaging surface of an image sensor.

[0113] (11) According to the imaging device described in (10), the OIS unit is configured to be able to change the position of the optical system relative to the image sensor.

[0114] (12) According to the imaging device of (10) or (11), the optical axis of the optical system at the reference position passes through the center of the imaging surface of the image sensor.

[0115] (13) An electronic device including the imaging device according to (8), further comprising a circuit board for supplying power to the imaging device.

[0116] (14) An image stabilization method, in optical image stabilization (OIS) in which the position of an optical system is changed, comprising:

[0117] removing or reducing a signal having a specific frequency from a signal indicating a target value of a reference position of an optical system;

[0118] performing feedback control to control the position of the optical system; and

[0119] The optical system is moved to a reference position between frames based on a signal indicating a target value by which a particular frequency has been removed or reduced.

[0120] (15) In the image stabilization method according to (14), the removal or reduction of the signal having the specific frequency is performed by a notch filter.

[0121] (16) In the image stabilization method according to (14) or (15), the removing or reducing includes weakening the degree of removing or reducing a signal having a specific frequency from a signal indicating a target value during an exposure period compared to a period between frames.

[0122] (17) In the image stabilization method according to any one of (14) to (16), the specific frequency includes a peak frequency in a closed-loop characteristic of the feedback control.

[0123] (18) In the image stabilization method described in any one of (14) to (17), the OIS includes controlling the position of the OIS unit in at least one direction different from the optical axis direction, the OIS unit having a movable part, the movable part being configured to support the optical system moving in the optical axis direction of the optical system through a flexible member so as to move in the moving direction of the movable part.

[0124] (19) In the image stabilization method according to (18), the at least one direction different from the optical axis direction of the optical system includes at least one of two directions orthogonal to the optical axis direction.

[0125] (20) In the image stabilization method according to any one of (14) to (19), the optical axis of the optical system at the reference position passes through the center of the movement area of ​​the optical system.

[0126] (21) In the image stabilization method according to any one of (14) to (19), an optical axis of the optical system at the reference position passes through the center of the imaging surface of the image sensor.

[0127] (22) In the image stabilization method according to any one of (14) to (21), the moving includes moving the optical system to a reference position in one step.

[0128] [Explanation of letters or numbers]

[0129] 1: Imaging device

[0130] 11: Lens barrel assembly

[0131] 11a: Imaging lens

[0132] 13: Image Sensor

[0133] 3: Anti-shake system

[0134] 31: AF / OIS housing

[0135] 33: AF / OIS magnet

[0136] 5: OIS unit

[0137] 51: OIS housing

[0138] 53: OIS base

[0139] 55: OIS coil

[0140] 57: OIS spring

[0141] 59: OIS Hall element

[0142] 6: OIS controller

[0143] 7: AF unit

[0144] 71: Lens bracket

[0145] 73: AF coil

[0146] 75: AF spring

[0147] 77: AF Hall element

[0148] 8: AF controller

[0149] 901: Gap

[0150] 903: Movable range

[0151] 905: Mobile Area

[0152] 907: Input signal

Claims

1. An anti-shake system, the anti-shake system comprising: an optical image stabilization (OIS) unit configured to be able to change the position of the optical system; a vibration suppressor configured to remove or reduce a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system; as well as An OIS controller is configured to perform feedback control to control the position of the optical system, and to move the optical system to the reference position between frames based on the signal indicating the target value at which the specific frequency has been removed or reduced.

2. The anti-shake system according to claim 1, wherein: The vibration suppressor includes a notch filter.

3. The anti-shake system according to claim 1, wherein: The vibration suppressor is configured to reduce the extent to which the signal having the specific frequency is removed or reduced from the signal indicating the target value during an exposure period compared to a period between the frames.

4. The anti-shake system according to claim 1, wherein: The specific frequency includes a peak frequency in a closed-loop characteristic of the feedback control.

5. The anti-shake system according to claim 1, wherein: The movable portion of the OIS unit is movable in at least one direction different from the direction of the optical axis of the optical system, and The movable portion supports the optical system that moves in the optical axis direction of the optical system via a flexible member so as to move in the moving direction of the movable portion.

6. The anti-shake system according to claim 1, wherein: The optical axis of the optical system at the reference position passes through the center of the movement area of ​​the optical system.

7. The anti-shake system according to claim 1, wherein: The OIS controller is configured to move the optical system to the reference position in one step.

8. An imaging device, the imaging device being equipped with the anti-shake system according to claim 1, the imaging device further comprising: an image sensor configured to generate an image signal based on a light beam capturing a scene; as well as An optical system is configured to form an image of a light beam from a photographic object on an imaging surface of the image sensor.

9. The imaging device according to claim 8, wherein: The OIS unit is configured to be able to change a position of the optical system relative to the image sensor.

10. The imaging device according to claim 8, wherein: The optical axis of the optical system at the reference position passes through the center of the imaging surface of the image sensor.

11. An electronic device, the electronic device being equipped with the imaging device according to claim 8, the electronic device further comprising: A circuit board is provided to supply power to the imaging device.

12. An image stabilization method, in an optical image stabilization (OIS) that changes the position of an optical system, the method comprising: removing or reducing a signal having a specific frequency from a signal indicating a target value of a reference position of the optical system; performing feedback control to control the position of the optical system; as well as The optical system is moved to the reference position between frames based on the signal indicating that the target value of the specific frequency has been removed or reduced.

Images