JP7313143B2 - Image stabilization device and imaging device - Google Patents

Description

The present invention relates to a blur correction device that corrects blurring during shooting, and an imaging apparatus that includes the blur correction device.

There are two methods of blur correction in a blur correction device mounted on an imaging device: a method of moving an optical lens in a direction orthogonal to the optical axis (hereinafter referred to as "optical axis orthogonal direction"), and a method of moving an image sensor in a direction orthogonal to the optical axis. For example, Japanese Patent Application Laid-Open No. 2002-200002 proposes a motion compensation device that uses a so-called voice coil motor having magnets and coils to move an imaging device in a direction perpendicular to the optical axis. Further, for example, Japanese Patent Application Laid-Open No. 2002-200001 proposes a configuration in which a motion compensation device using a voice coil motor is installed in an imaging lens, and a magnetic field generated by the coil is shielded by a shielding member made of a magnetic material.

JP 2010-15107 A JP 2017-173757 A

However, with the technique described in Patent Literature 1, electromagnetic waves generated from the coil may cause electronic components mounted in the main body of the imaging apparatus to malfunction. For example, when the coil is arranged near the imaging element, the magnetic field generated by the coil may reach the imaging element and affect the image as magnetic noise. Here, a configuration in which the shielding member described in Patent Document 2 is arranged between the imaging device and the coil is conceivable, but it may be difficult to place the shielding member because the distance between the shielding member and the imaging device is narrow, or the arrangement of the shielding member increases the size of the imaging device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a blur correction device capable of reducing the influence of a magnetic field on an imaging device while avoiding an increase in size.

A motion compensation device according to the present invention includes a movable part having an imaging element and a fixed part that movably supports the movable part, wherein the imaging element is movable in a plane parallel to a light receiving surface of the imaging element, wherein the movable part comprises one or more coils, a holding member that holds the coils, and a non-magnetic metal, and is plate-shaped and arranged on a surface of the holding member opposite to the surface on which the coil is mounted.and a second shielding portion made of a non-magnetic metal and arranged along a side wall facing the coil side in the imaging elementand, the fixed portion includes a permanent magnet arranged at a position facing the coil, and when viewed from a direction orthogonal to the light receiving surface of the imaging element, thefirst shieldcovers at least a part of the coil, and the hollow portion of the coil and the center of the permanent magnet overlap in the first direction parallel to the light receiving surface of the imaging element.first shieldis shorter than the distance from the end of the permanent magnet to the imaging elementand a gap is provided between the first shielding portion and the second shielding portion in the first direction.It is characterized by

According to the present invention, it is possible to provide a blur correction device that reduces the influence of a magnetic field on an imaging device while avoiding an increase in size.

1A and 1B are a central sectional view of an imaging device and a block diagram showing an electrical configuration of the imaging device; FIG. 1A and 1B are an external perspective view and an exploded perspective view of a blur correction unit according to a first embodiment; FIG. 1A and 1B are a top view and a cross-sectional view of a blur correction unit according to a first embodiment; FIG. 4A and 4B are diagrams schematically showing magnetic fields in each of the blur correction unit according to the first embodiment and the blur correction unit according to the reference example; FIG. 5 is a diagram for explaining the effect of reducing magnetic noise due to eddy currents generated in the shielding member in the blur correction unit according to the first embodiment; FIG. 11 is a perspective view showing a schematic configuration of a movable portion that constitutes a motion compensation unit according to a second embodiment; 7A and 7B are diagrams schematically showing magnetic fields in the blur correction unit including the movable part of FIG. 6 and a blur correction unit according to a modification thereof; FIG. 7 is a perspective view showing a modification of the movable portion of FIG. 6, and a diagram schematically showing a magnetic field in a blur correction unit including this movable portion. It is a figure explaining the desirable shape of the standing bending surface part provided in a shielding member. It is a figure explaining another shape of the standing bending surface part provided in a shielding member.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1(a) is a central cross-sectional view of an imaging device according to an embodiment of the present invention, and FIG. 1(b) is a block diagram showing the electrical configuration of the imaging device.

The imaging device has a camera body 1 (imaging device body) and a photographing lens 2 (lens barrel) attached to the camera body 1 . Here, the photographing lens 2 and the camera body 1 are mechanically detachable, and are electrically connected at the electrical contact 11 in the mechanically coupled state. Note that the photographing lens 2 is not limited to this, and the photographing lens 2 may be configured integrally (not detachably) with the camera body 1 .

The photographing lens 2 includes a photographing optical system 3 composed of a plurality of lenses, a lens driving unit 13 that drives various lenses such as a focus lens and a zoom lens that constitute the photographing optical system 3, and a diaphragm (not shown), and a lens system control unit 12 that controls the operation of the lens driving unit 13. The camera body 1 has a camera system control section 5 , an image sensor 6 , an image processing section 7 , a storage section 8 , a display section 9 , an operation detection section 10 , a blur correction unit 14 , a blur detection section 15 , a shutter unit 16 and a shutter driving section 17 . The display unit 9 includes a rear display device 9a and an EVF 9b.

For convenience of explanation, as shown in FIG. 1(a), the X-axis, Y-axis, and Z-axis that are orthogonal to each other with respect to the imaging apparatus are defined. The Z axis is an axis parallel to the optical axis of the photographing lens 2 and an axis substantially perpendicular to the light receiving surface (imaging surface) of the image sensor 6 . The X-axis is the axis perpendicular to the Z-axis in the horizontal plane when the Z-axis is parallel to the horizontal direction. The Y-axis is the axis parallel to the vertical direction while the Z-axis is parallel to the horizontal direction.

The luminous flux that has passed through the photographing optical system 3 forms an image on the imaging element 6 , which converts the optical image into an electric signal by photoelectric conversion and outputs the electric signal to the image processing section 7 . At that time, a focus evaluation amount and an appropriate amount of exposure can be obtained by the image pickup element 6, and an appropriate amount of object light is exposed to the image pickup element 6 by appropriately adjusting the photographing optical system 3 based on the obtained amounts. Further, the amount of exposure to the imaging element 6 is controlled by the shutter unit 16 running the shutter curtain. The driving of the shutter unit 16 is controlled by a shutter driving section 17 that follows commands from the camera system control section 5 .

The image processing unit 7 has therein an A/D converter, a white balance adjustment circuit, a gamma correction circuit, an interpolation calculation circuit, etc., and generates digital data of an image (video) for storage. The image processing unit 7 has a color interpolation processing circuit, and the color interpolation processing circuit performs color interpolation (demosaicing) processing from the Bayer array signal to generate a color image. The image processing unit 7 also compresses image data, moving image data, and audio data using a predetermined method. The storage unit 8 includes a semiconductor storage device such as an EEPROM for storing programs executed by the camera system control unit 5, a memory card for storing various data generated by the image processing unit 7, and the like.

The operation detection unit 10 detects operations on various operation members provided on the camera body 1 and notifies the camera system control unit 5 of detection results. The camera system control section 5 executes processing corresponding to the notification from the operation detection section 10 . For example, when a release button included in the operation detection unit 10 is pressed, the camera system control unit 5 executes a series of well-known imaging operations such as imaging preparation processing, imaging processing, image processing, and storage processing.

The rear display device 9a displays various kinds of information such as a subject image, a photographed image, setting information of the imaging device, and the like. The rear display device 9a is a touch panel, and has a function of detecting a touch operation as one of the operation detection units 10. FIG. A photographer (user) can confirm a subject image by looking into the EVF 9a.

The shake detection unit 15 has a sensor such as a vibration gyroscope, detects rotational shake of the camera body 1 including rotations around the X-axis, Y-axis and Z-axis, and transmits the shake detection result to the camera system control unit 5 . The camera system control unit 5 controls driving of the blur correction unit 14 so as to cancel out the detected blur based on the blur detection result from the blur detection unit 15, thereby driving the imaging device 6 in directions (X direction, Y direction) perpendicular to the optical axis (Z axis). The blur correction unit 14 is configured so that the imaging element 6 can be translated in a plane (in the XY plane) perpendicular to the optical axis and can be rotated around the optical axis (around the Z axis).

The camera system control unit 5 performs overall control of the imaging device by centrally controlling the operation of each unit that configures the imaging device. The camera system control section 5 also transmits commands to the lens system control section 12 via the electrical contact 11 . The lens system control section 12 drives the lens drive section 13 according to the command from the camera system control section 5 and transmits the result (operation information of the photographing lens 2 and the like) to the camera system control section 5 .

<First embodiment>
Next, the blur correction unit 14 according to the first embodiment of the invention will be described. 2A is an external perspective view of the blur correction unit 14, and FIG. 2B is an exploded perspective view of the blur correction unit 14. FIG. 3(a) is a top view of the blur correction unit 14, and FIG. 3(b) is a cross-sectional view of the blur correction unit 14 taken along the arrow AA shown in FIG. 3(a). Since the blur correction unit 14 moves the image sensor 6 within a plane orthogonal to the optical axis, the image sensor 6 is also shown in FIGS. Note that the photographing lens 2 not shown in FIGS. 3 and 3 is arranged on the Z-axis positive direction side.

The blur correction unit 14 is generally composed of a movable portion 50 , an upper fixed portion 60 and a lower fixed portion 70 . The movable part 50 is supported by the upper fixing part 60 and the lower fixing part 70 so as to be movable in a plane orthogonal to the optical axis with respect to the upper fixing part 60 and the lower fixing part 70 .

The imaging device 6 is included in the movable section 50 . The movable part 50 has a movable frame 51 , coils 53 a , 53 b , 53 c , magnetic sensors 54 a , 54 b , 54 c , FPC 55 (flexible printed circuit board), and a shielding member 56 . The upper fixing portion 60 has an upper yoke 61 and permanent magnets 62a, 62b, 62c, 62d, 62e, and 62f. The bottom fixing portion 70 has a base plate 71 , ball rolling surfaces 72 a , 72 b and 72 c , main spacers 73 a , 73 b and 73 c , sub spacers 74 a , 74 b and 74 c and a bottom yoke 75 . Further, the lower surface fixed portion 70 has permanent magnets 76a, 76b, 76c, 76d, 76e, and 76f, and rolling balls 77a, 77b, and 77c.

The upper surface yoke 61 and magnets 62a to 62f of the upper surface fixing portion 60 and the lower surface yoke 75 and magnets 76a to 76f of the lower surface fixing portion 70 form a magnetic circuit (so-called closed magnetic circuit). Each of the magnets 62a to 62f is adhered and fixed to the upper yoke 61 while being attracted thereto. Similarly, the magnets 76a to 76f are adhered and fixed to the lower yoke 75 while being attracted to each other. The magnets 62a-62f and 76a-76f are magnetized in the optical axis direction (Z-axis direction). Specifically, each pair of adjacent magnets [magnet 62a, magnet 62b], [magnet 62c, magnet 62d], [magnet 62e, magnet 62f], [magnet 76a, magnet 76b], [magnet 76c, magnet 76d], and [magnet 76e, magnet 76f] are magnetized in different directions. As an example, the magnets 62e, 62f, 76e, and 76f shown in FIG. 3(b) are indicated by symbols S and N indicating the magnetization directions, and it can be seen that the adjacent magnets 62e and 62f have different magnetization directions, and the magnets 76e and 76f have different magnetization directions. On the other hand, magnets arranged to face each other in the Z-axis direction are magnetized in the same direction. For example, as shown in FIG. 3B, the magnets 62e and 76e are magnetized in the same direction, and the magnets 62f and 76f are magnetized in the same direction. The same is true for each combination of magnets 62a, 76a, magnets 62b, 76b, magnets 62c, 76c, and magnets 62d, 76d. With such a configuration, a strong magnetic flux density is generated between the upper yoke 61 and the lower yoke 75 in the optical axis direction.

A predetermined space is maintained between the upper yoke 61 and the lower yoke 75 by main spacers 73a, 73b, 73c and sub-spacers 74a, 74b, 74c arranged therebetween. The movable portion 50 is arranged with a predetermined gap between the upper yoke 61 and the lower yoke 75 . Rubber is installed on the cylindrical side portions of the main spacers 73a, 73b, and 73c to form mechanical ends (stoppers) of the movable portion. The base plate 71 and the lower yoke 75 are fixed by screws (not shown). The magnets 76a to 76f are larger than the base plate 71 in the thickness direction (Z-axis direction). A hole is provided in the base plate 71 so as to avoid the magnets 76a to 76f. The magnets 76a to 76f are fixed to the lower yoke 75 so that each surface of the magnets 76a to 76f protrudes from the base plate 71 through each hole provided in the base plate 71 in the Z-axis direction.

A movable frame 51 constituting the movable portion 50 is made of non-magnetic metal such as aluminum die-cast. An imaging element 6 , an FPC 55 and a shielding member 56 are mounted on the movable frame 51 . The coils 53a, 53b, and 53c are mounted (fixed) on the surface of the FPC 55 on the lower surface fixing portion 70 side (negative direction side of the Z axis), and electrically communicate with the outside through a connector (not shown). The coils 53a to 53c are arranged substantially on the same plane with respect to the imaging element 6, with the axial direction of the hollow portion formed by the windings being substantially parallel to the optical axis.

The magnetic sensors 54a, 54b, 54c are respectively mounted on the FPC 55 inside the hollow inside the windings of the coils 53a, 53b, 53c, and electrically communicate with the outside through connectors (not shown). For example, FIG. 3B shows a state in which a magnetic sensor 54c is mounted in a hollow portion formed by the winding of a coil 53c. The magnetic sensors 54a to 54c are Hall elements or the like, for example, and detect the position when the movable part 50 moves within a plane perpendicular to the optical axis using the magnetic circuit described above. In this way, the FPC 55 serves as a holding member that holds the coils 53a to 53c and the magnetic sensors 54a to 54c, and also as a connecting member that electrically connects the coils 53a to 53c and the magnetic sensors 54a to 54c to the camera system controller 5.

A thin plate-shaped shielding member 56 made of nonmagnetic metal is adhered to the surface of the FPC 55 opposite to the surface on which the coils 53a to 53c are mounted (upper surface fixing portion 60 side). The shielding member 56 has substantially the same shape as the FPC 55, and is designed to cover substantially the entire surface of the coils 53a to 53c when projected in the optical axis direction. A material having a low magnetic permeability and a high electrical conductivity is preferably used for the shielding member 56, and aluminum is used here. Considering the size of the motion compensation unit 14 in the Z-axis direction, the thickness of the shielding member 56 is preferably about 0.1 mm to 0.5 mm.

If the shielding member 56 is made of a magnetic material with a high magnetic permeability, the magnetic field of the magnetic circuit formed by the upper surface fixing portion 60 and the lower surface fixing portion 70 is disturbed, and the magnetic flux efficiently reaches the coils 53a to 53c. Further, if the shielding member 56 has a high magnetic permeability, the movable portion 50 may be pulled by the magnetic forces from the magnets 62a to 62f and 76a to 76f, which may interfere with the drive control of the movable portion 50. FIG. From the viewpoint of avoiding the occurrence of such problems, it is desirable to use a material with low magnetic permeability for the shielding member 56 . Details of the reason why it is desirable to use a material with high conductivity for the shielding member 56 will be described later.

When a current is passed through the coils 53a to 53c under the control of the camera system control section 5, the movable section 50 can be moved by generating a force according to Fleming's left-hand rule. At that time, feedback control can be performed by using the output signals from the magnetic sensors 54a to 54c. By appropriately controlling the values of the output signals from the magnetic sensors 54a to 54c and controlling the currents flowing through the coils 53a to 53c, the movable part 50 can be translated in a plane perpendicular to the optical axis and rotated about an axis substantially parallel to the optical axis. For example, by controlling the current flowing through the coil 53c, the movable portion 50 translates in the indicated X-axis direction. Further, by controlling the currents flowing through the coils 53a and 53b, the movable portion 50 can be translated in the Y-axis direction or rotated around an axis substantially parallel to the optical axis. Many proposals have been made for the details of control methods including feedback control, and such known techniques can be used, so a detailed description is omitted here.

The shake correction unit 14 is made thinner (downsized in the Z-axis direction) by using the FPC 55 for mounting the coils 53a to 53c and the magnetic sensors 54a to 54c. However, since the FPC 55 is flexible, the coils 53a to 53c act as electromagnets when a current is passed through the coils 53a to 53c. Therefore, the magnetic sensors 54a-54c are arranged in the hollow portions of the coils 53a-53c, respectively. In this case, the position of the movable part 50 is erroneously detected because the output signals of the magnetic sensors 54a to 54c change even if the movable part 50 does not move in a plane substantially perpendicular to the optical axis. In order to deal with such a problem, the FPC 55 is adhered to the shielding member 56 made of metal to prevent the FPC 55 from bending, thereby suppressing erroneous detection due to movement of the magnetic sensors 54a to 54c.

The camera system control unit 5 performs so-called PWM control, which controls the drive voltage by controlling the pulse width (duty ratio) of the high-frequency signal when currents flow through the coils 53a to 53c. In the PWM control, a high-frequency, small-amplitude alternating current flows through the coils 53a to 53c due to the driving frequency of the PWM control, superimposed on the low-frequency direct current due to the driving voltage in the PWM control. Therefore, a magnetic field is generated from the coils 53a to 53c by applying current to the coils 53a to 53c, and the generated magnetic field reaches the image pickup device 6, thereby generating magnetic noise in the video signal of the image pickup device 6. FIG. In particular, it is known that a magnetic field generated by a change in the high-frequency current caused by the drive frequency of PWM control affects the video signal of the imaging device 6 .

As shown in FIG. 3B, the imaging element 6 arranged on the movable frame 51 has a base material portion 6a, a chip portion 6b and a glass portion 6c. The chip portion 6b is made of a silicon layer, has a light-receiving surface on which light from the imaging optical system 3 forms an image, and has a light-receiving portion that converts the optical image formed on the light-receiving surface into an electric signal by photoelectric conversion. Also, the chip portion 6b is provided with a circuit for exchanging signals from the light receiving portion. The land portion of the chip portion 6b is connected to a wiring layer arranged on the base portion 6a by wire bonding (not shown), and the wiring layer of the base portion 6a is further connected to a substrate (not shown).

As shown in FIG. 3(b), in the motion compensation unit 14, the coils 53a to 53c and the imaging element 6 are arranged substantially on the same plane to reduce the thickness. However, the configuration in which the imaging device 6 and the coils 53a to 53c are arranged substantially on the same plane in the movable section 50 has the following problems. That is, when the magnetic field generated by the coils 53a to 53c reaches the chip portion 6b of the imaging device 6, the image acquired by the imaging device 6 is affected as magnetic noise. For example, if the imaging lens is equipped with a motion compensation device that includes a coil, the coil is farther from the imaging element than in the present embodiment, so the magnetic field generated by the coil has little effect on the imaging element. However, in a configuration in which the coils 53a to 53c and the imaging element 6 are close to each other, as in the blur correction unit 14, the magnetic fields generated by the coils 53a to 53c have a greater influence on the imaging element 6, and the output signal from the imaging element 6 is likely to be mixed with magnetic noise.

Therefore, in the blur correction unit 14, by arranging the shielding member 56, the thickness of the blur correction unit 14 is reduced and the influence of the magnetic field generated by the coils 53a to 53c on the imaging element 6 is reduced. Next, referring to FIG. 4, the shielding effect of the shielding member 56 against the magnetic fields generated by the coils 53a to 53c will be described. In particular, the blur correction unit 14 has the effect of reducing the influence of the high-frequency magnetic field on the imaging device 6 that is generated by changes in the high-frequency current caused by the driving frequency of PWM control.

FIG. 4(a) is an enlarged view of the main part (the left part of FIG. 3(b)) of the cross-sectional view shown in FIG. 3(b), schematically showing the magnetic field generated by the coil 53c. FIG. 4B is a diagram schematically showing the magnetic field generated from the coil 53c in the blur correction unit according to the reference example in which the shielding member 56 is removed from the blur correction unit 14. As shown in FIG.

Arrows 81 and 82 in FIGS. 4A and 4B respectively indicate the flow (advancing direction) of the magnetic field (magnetic flux) generated from the coil 53c. Although the magnetic field generated from the coil 53c is generated in greater quantity and more densely than indicated by the arrows 81 and 82, each magnetic field is schematically shown to explain the effect on the imaging element 6. FIG.

First, FIG. 4B showing the configuration of the reference example will be described. The magnetic field generated from the lower surface side of the hollow portion of the coil 53c proceeds as indicated by arrow 82a, branches and merges as indicated by arrows 82b, 82c, 82d, 82e, 82f, and 82g, and reaches the upper surface side (Z-axis positive direction side) of the hollow portion of coil 53c. At this time, since the movable frame 51 is made of highly conductive aluminum die-cast and has a certain thickness, the high-frequency magnetic field hardly passes through the movable frame 51 due to the skin effect, and proceeds avoiding the movable frame 51 as indicated by arrows 82b and 82f.

The magnetic field passing through the gap 40 between the coil 53c and the movable frame 51 is indicated by an arrow 82b, and the magnetic field that advances as indicated by the arrow 82b branches into the magnetic field that advances toward the upper surface of the coil 53c as indicated by the arrow 82c, and the magnetic field that advances toward the imaging element 6 as indicated by arrows 82d and 82g. In this case, if the magnetic field reaching the tip portion 6b of the image sensor 6 is strong as indicated by an arrow 82g, the signal of the image sensor 6 is affected by magnetic noise. Since the upper yoke 61 and the lower yoke 75 are made of a magnetic material, the magnetic field passes through the upper yoke 61 and the lower yoke 75, and the magnetic field indicated by the arrow 82e passes through the upper yoke 61 and reaches the upper surface of the coil 53c.

Next, FIG. 4A showing the configuration of the blur correction unit 14 according to this embodiment will be described. The magnetic field generated from the lower surface side of the hollow portion of the coil 53c proceeds as indicated by the arrow 81a, branches and joins as indicated by the arrows 81b, 81c, 81d, 81e, 81f, 81g, and 81h, and reaches the upper surface side (Z-axis positive direction side) of the hollow portion of the coil 53c. Arrows 81h and 81g following the arrow 81b schematically represent magnetic fields passing through the FPC 55 located between the coil 53c and the shielding member 56 . Since the FPC 55 is mainly made of resin, most of the magnetic field passes through the FPC 55 .

On the other hand, since the shielding member 56 is made of aluminum and has a certain thickness, it has the effect of preventing transmission of the high-frequency magnetic field due to the skin effect, as described above. Therefore, most of the magnetic field indicated by the arrow 81b passing through the gap 40 between the movable frame 51 and the coil 53c proceeds in the direction indicated by the arrow 81h due to the presence of the shielding member 56, and the remaining magnetic fields advance in the directions indicated by the arrows 81d, 81c, and 81g. In FIG. 4A, the arrows 81d, 81c, and 81g are drawn with a line width narrower than the line width of the arrows 82d, 82c, and 82g shown in FIG.

The shielding member 56 does not completely shield the magnetic field, and since the shielding member 56 is thin, part of the magnetic field passes through the shielding member 56 as indicated by arrows 81c and 81d. Moreover, as indicated by an arrow 81g, it is considered that there is also a magnetic field that reaches the tip portion 6b of the imaging element 6 after traveling along the shielding member 56. FIG. However, comparing the arrows 81c, 81d and 81h, the magnetic field indicated by the arrow 81h is relatively larger than the magnetic field indicated by the arrows 81c and 81d, so the magnetic field reaching the tip portion 6b can be reduced.

4(a) and 4(b), the manner in which the magnetic field is generated when the current flows in one direction in the coil 53c has been described. However, since the voltage applied by PWM control contains an AC component, the current may change in the opposite direction when the blur correction unit 14 is actually driven. In that case, the magnetic field generated from the coil 53c is generated as a vector in the opposite direction. For example, in the case of FIG. 4(a), the magnetic field generated by the coil 53c only travels in the reverse paths of the arrows 81a to 81h, so the effects of the shielding member 56 can be similarly obtained as described above.

By the way, an eddy current is generated in the shielding member 56 by receiving the magnetic field of the coil 53c, and a demagnetizing field is generated to cancel the magnetic field of the arrow 81a. Therefore, the effect of the eddy current generated in the shielding member 56 will now be described. FIG. 5 is a diagram for explaining the effect of reducing magnetic noise due to eddy currents generated in the shielding member 56. Here, the coil 53 is taken as an example for explanation. For convenience, FIG. 5 shows part of the shielding member 56 as a rectangle. Since the magnetic field passes through the FPC 55, the FPC 55 present between the coil 53c and the shielding member 56 is omitted in FIG. Furthermore, in FIG. 5, the space between the coil 53c and the shielding member 56 is drawn wide.

When a current I is passed through the coil 53c in the direction indicated by the arrow 111, a magnetic field indicated by the arrow 112 is generated from the coil 53c. The generated magnetic field interlinks the surface of the shielding member 56 facing the coil 53c, and an eddy current Ie is generated on the surface of the shielding member 56. FIG. The eddy current Ie generates a magnetic field Bc indicated by arrow 114 that cancels the magnetic field indicated by arrow 112 . Due to the canceling effect of the magnetic field Bc, the magnetic field generated from the coil 53c is reduced as a whole.

When the current I flows in the direction opposite to the direction of the arrow 111, the direction of the magnetic field generated by the coil 53c (arrow 112), the direction of the flow of the eddy current Ie, and the direction of the magnetic field generated by the eddy current Ie (arrow 114) are reversed. Arrow 112 points in the positive direction of the Z-axis as applied to FIG. 4(a). That is, FIG. 4A shows a state in which such reversal occurs. When a magnetic field is generated in the direction of arrow 81a shown in FIG. 4(a), the strength of the magnetic field indicated by arrow 81a generated by coil 53c is reduced due to the magnetic field generated by the eddy current generated by shielding member 56. As shown in FIG. As a result, the magnetic field reaching the imaging device 6 is further reduced.

So far, the relationship between the magnetic field generated by the coil 53c and the shielding member 56 has been described. As described above, in the motion compensation unit 14 having the movable portion 50 including the coils 53a to 53c and the imaging element 6 according to the present embodiment, the thin plate-like shielding member 56 is arranged on the upper surfaces of the coils 53a to 53c. As a result, it is possible to reduce the influence of the magnetic fields generated by the coils 53a to 53c on the imaging element 6 while avoiding an increase in size and achieving a thin design. As a result, it is possible to suppress electromagnetic noise from being mixed into the output signal from the imaging device 6 and obtain a high-quality image signal (video signal).

In this embodiment, the shielding member 56 has a shape substantially equivalent to that of the FPC 55, and has a shape that covers substantially the entire surface of the coils 53a to 53c when projected in the optical axis direction. However, the present invention is not limited to this, and if the shielding member 56 has a shape that covers at least a part of the coils 53a to 53c when projected in the optical axis direction, the effect of reducing the influence of the magnetic field generated by the coils 53a to 53c on the imaging element 6 can be obtained. For example, if the shielding member 56 covers the hollow portions of the coils 53a to 53c when projected in the optical axis direction, an eddy current can be generated in the shielding member 56, and the magnetic field generated from the coils 53a to 53c can be reduced as a whole. Further, if the shielding member 56 extends to the position (the position of the dashed line 40e) covering the gap 40 (see FIG. 4A) between the movable frame 51 and the coil 53c, the magnetic field indicated by the arrow 81h can be generated, thereby reducing the reach of the magnetic field to the imaging element 6. The effect of reducing the magnetic field by the shielding member 56 is determined by the frequency of the magnetic field to be reduced by the skin effect and the conductivity of the shielding member 56. If a highly conductive material such as copper is used for the shielding member 56, a greater effect can be obtained.

<Second embodiment>
FIG. 6 is a perspective view showing a schematic configuration of a movable portion 50A provided in a blur correction unit 14A (see FIG. 7A) according to the second embodiment of the invention. The movable portion 50A of the blur correction unit 14A has a shielding member 56S according to a modified example of the shielding member 56. As shown in FIG. The difference between the blur correction unit 14A according to the second embodiment and the blur correction unit 14 according to the first embodiment is the difference in structure (shape) between the shielding member 56S and the shielding member 56. FIG.

Note that the overall configuration of the blur correction unit 14A according to the second embodiment is the same as that of the blur correction unit 14 described in the first embodiment, except for the structure (shape) of the shielding member 56S. That is, the blur correction unit 14A includes a movable portion 50A, an upper surface fixed portion 60, and a lower surface fixed portion 70. As shown in FIG. Therefore, in the following description, description of the upper surface fixing portion 60 and the lower surface fixing portion 70 will be omitted. Further, among the constituent elements of the movable section 50A, constituent elements common to the movable section 50 described in the first embodiment will be explained by applying the constituent elements of the movable section 50 as they are. However, the explanation of the matters already explained will be omitted.

As shown in FIG. 6, the shielding member 56S has standing bent surface portions 56b and 56c and notch portions 56d and 56e, and differs from the shielding member 56 in this respect. The standing bent surface portions 56b and 56c are formed by bending substantially perpendicularly to the opposite side (positive direction of the Z axis) of the side of the shielding member 56S on the imaging element 6 side, on which the coils 53a to 53c are mounted. The notch portions 56d and 56e are provided at the base portions of the upright curved surface portions 56b and 56c, respectively, on the plane perpendicular to the optical axis of the shielding member 56S. That is, the notch portions 56d and 56e are not provided in the standing bending surface portions 56b and 56c.

FIG. 7(a) is a cross-sectional view similar to FIG. 4(a) showing the configuration of the main part of the blur correction unit 14A having the movable part 50A, and schematically shows the magnetic field generated by the coil 53c. FIG. 7(b) is a cross-sectional view similar to FIG. 7(a) showing the configuration of the main part of the blur correction unit 14B having a movable portion having a shielding member 56T without cutouts 56d and 56e instead of the shielding member 56S, and schematically showing the magnetic field generated from the coil 53c. Arrows 83 and 84 respectively indicate the magnetic fields generated from the coil 53c in the same manner as the arrows 81 and 82 shown in FIG. 4, but FIGS.

FIG. 7(a) showing the movable portion 50A will be described. The magnetic field generated from the lower surface side of the hollow portion of the coil 53c proceeds in the direction indicated by the arrow 83a, and part of the magnetic field passes through the gap 40 between the movable frame 51 and the coil 53c as indicated by the arrow 83b, as in FIG. 4(a). Most of the magnetic field indicated by arrow 83b proceeds in the direction of arrow 83h due to shielding member 56S, and the remaining branched magnetic field proceeds in the directions of arrows 83c and 83i.

The magnetic field traveling in the direction of the arrow 83i passes through the notch 56d, travels in the direction of the arrow 83d along the magnet 62f side surface of the bent surface 56b, and then merges with another magnetic field as indicated by the arrow 83e. In the movable portion 50A, the shielding member 56S is provided with the notch portion 56d and the bent surface portion 56b. Therefore, the amount of the magnetic field that passes through the notch portion 56d and leaks to the right side of the bent surface portion 56b (that is, to the image sensor 6 side) can be reduced.

FIG. 7(b) shows a movable portion comprising a shielding member 56T having a bent surface portion 56b but no notch portion 56d. Compared to the shielding member 56 described in the first embodiment, the shielding member 56T has an upright curved surface portion 56b but does not have a notch portion 56d. Therefore, the resistance value decreases due to the increase in volume, and the flowing eddy current increases. As the magnetic field generated by the eddy current is thus increased, the effect of canceling the magnetic field generated by the coil 53c is also increased. As a result, the magnitude of the magnetic field indicated by arrow 84a in FIG. 7B is smaller than the magnetic field indicated by arrow 81a in FIG.

On the other hand, the magnetic field generated from the lower surface side of the hollow portion of the coil 53c advances as indicated by the arrow 84a, and part of the magnetic field advances in the direction indicated by the arrow 84b through the gap 40 between the movable frame 51 and the coil 53c, as in FIG. 4(a). The magnetic field indicated by arrow 84b travels mostly in the direction of arrow 84h due to shielding member 56T, with the remainder of the magnetic field branching out in the directions of arrows 84c and 84i. The magnetic field advancing in the direction of arrow 84i travels in the direction indicated by arrow 84g from the root of the bent surface portion 56b, and then merges with another magnetic field as indicated by arrow 84e.

The magnetic field indicated by the arrow 84g leaks to the chip portion 6b of the imaging device 6 and causes magnetic noise to be mixed in the output signal of the imaging device 6. FIG. Here, as described above, in the shielding member 56T, the magnitude of the magnetic field indicated by the arrow 84a in FIG. 7(b) is smaller than the magnetic field indicated by the arrow 81a in FIG. 4(a). Therefore, even with the configuration of FIG. 7(b), it is possible to suppress leakage of the magnetic field to the tip portion 6b as compared with the configuration shown in FIG. 4(a). However, in order to further reduce the leakage of the magnetic field to the imaging device 6, it is desirable to further provide notches 56d and 56e like the shielding member 56S shown in FIG. 7(a).

Next, another example of the shielding member having cutouts will be described. FIG. 8(a) is an external perspective view of a movable portion 50B having a shielding member 56U. FIG. 8(b) is a cross-sectional view similar to FIG. 4(a) showing the configuration of the main part of the blur correction unit 14C having the movable part 50B, and schematically shows the magnetic field generated from the coil 53c.

In the shielding member 56U, a notch portion 56m is provided on the bent-up surface portion 56b, and a notch portion 56n is provided on the bent-up surface portion 56c. In the blur correction unit 14C, the magnetic field generated from the lower surface side of the hollow portion of the coil 53c proceeds in the direction indicated by the arrow 85a, and part of the magnetic field passes through the gap 40 between the movable frame 51 and the coil 53c as indicated by the arrow 85b, as in FIG. 4(a). Most of the magnetic field indicated by arrow 85b proceeds in the direction of arrow 85h due to shielding member 56U, and the remaining branched magnetic field proceeds in the directions of arrows 85c and 85i. The magnetic field advancing in the direction of arrow 84i branches off from the root of the upright bent surface portion 56b and advances in the directions indicated by arrows 85g and 85j.

In the configuration of the movable portion 50B, there is a magnetic field leaking into the tip portion 6b of the imaging device 6 as indicated by an arrow 85g. However, since the notch portion 56m is provided in the upright bending surface portion 56b, part of the magnetic field that has entered the imaging device 6 passes through the notch portion 56m and escapes to the outside of the imaging device 6, as indicated by an arrow 85j. As a result, the blur correction unit 14C can reduce the magnetic field leaking into the chip portion 6b of the imaging element 6 more than the blur correction unit 14B shown in FIG. 7B.

It can be seen that in each of the configurations described above, the magnetic field noise reduction effect on the image sensor 6 increases in the following order: blur correction unit 14 (FIG. 4(a))<blur correction unit 14B (FIG. 7(b))<blur correction unit 14C (FIG. 8)<blur correction unit 14A (FIG. 7(a)). From this, it can be seen that the conditions for more effectively reducing the magnetic field leaking to the image pickup device are to provide the shielding member with a vertically bent surface portion, to provide a notch portion near the vertically bent surface portion, and to provide the notch portion on a plane parallel to the imaging surface at the base of the vertically bent surface portion.

Next, a more desirable shape of the standing curved surface portion 56b formed on the shielding member 56S will be described. FIG. 9 is a diagram for explaining a desirable shape of the standing bent surface portion 56b. In addition, FIG. 9 is a diagram in which only the parts of the movable portion 50 are written out from the cross-sectional view of FIG. 7A and a part thereof is enlarged.

In FIG. 9, the magnetic fields indicated by arrows 83j and 83k schematically represent how the magnetic field indicated by arrow 83d branches. It is desirable that the standing bending surface portion 56b has a shape in which the standing bending surface front end portion 56f, which is the front end portion of the standing bending surface portion 56b, is positioned on the positive direction side of the Z-axis with respect to the broken line 44. FIG. Here, the dashed line 44 is a line that connects a notch end face portion 56g, which is the end face of the notch portion 56d on the X-axis negative direction side, and the upper end portion 6d of the side wall (upper surface) on the X-axis negative direction side of the tip portion 6b of the imaging device 6. In other words, it is desirable that the bending surface tip portion 56f extends in the Z-axis positive direction (toward the photographing optical system) from the surface connecting the notch end surface portion 56g and the upper end portion 6d.

If the bending surface tip 56f is located on the Z-axis negative direction side of the dashed line 44, and the magnetic field indicated by the arrow 83d is branched from the bending surface tip 56f to the imaging device 6 side, the magnetic field branched to the imaging device 6 side will easily reach the tip portion 6b. On the other hand, when the tip of the bent surface 56f is positioned on the Z-axis positive direction side of the dashed line 44, the magnetic field indicated by the arrow 83d after passing through the notch 56d may bypass the tip of the bent surface 56f toward the imaging element 6, like the magnetic field indicated by the arrow 83k. In this case, the magnetic field reaching the tip portion 6b is small, so that the influence on the output signal from the imaging device 6 can be reduced.

If the vertical bent surface portion 56b is long in the Z-axis direction (the vertical bent surface tip portion 56f extends long in the Z-axis positive direction), leakage of the magnetic field generated from the coil 53c to the imaging device 6 can be reduced, but the blur correction unit 14 becomes thicker in the Z-axis direction. In order to avoid this problem, it is not necessary to extend the leading end portion 56f of the standing bent surface beyond the dashed line 44 toward the positive direction of the Z axis (toward the photographing optical system).

<Third Embodiment>
In the third embodiment, another shape of the notch portions 56d and 56e of the shielding member 56S will be described. FIG. 10(a) is an external perspective view of a movable portion having a shielding member 56U with notches 56h and 56i. FIG. 10(b) is a top view of a movable portion having a shielding member 56U.

In the shielding member 56S described in the second embodiment, the planar portion perpendicular to the optical axis direction and the bent surface portion 56c of the shielding member 56S are connected at both ends of the bent surface portion 56c in the X-axis direction. With a structure similar to this, a standing bent surface portion 56b and a notch portion 56d are also formed.

The upright curved surface portion 56b and the notch portion 56d formed in the shielding member 56U are the same as those formed in the shielding member 56S. On the other hand, the bent surface portion 56c formed on the shielding member 56U is connected to the planar portion of the shielding member 56U perpendicular to the optical axis direction by a bent portion 56j provided at the central portion of the bent surface portion 56c in the X-axis direction. The bent surface portion 56b is arranged so as to be in contact with the side wall (YZ plane) of the image pickup element 6, while the bent surface portion 56c is arranged so as to form a predetermined gap with the side wall (ZX plane) of the image pickup element 6. As a result, the notch portions 56h and 56i formed at the root portion of the standing bent surface portion 56c are connected to form a substantially U-shape.

The bent portion 56j is provided so as not to be positioned on the dashed line 45 connecting the hollow portion of the coil 53a and the end portion 6e of the tip portion 6b. Similarly, the bent portion 56j is provided so as not to be positioned on a line (not shown) connecting the hollow portion of the coil 53b and the end portion 6e of the tip portion 6b. As a result, similar to the notch portion 56e of the shielding member 56S, the notch portions 56h and 56i can enhance the effect of guiding the magnetic field. It is also effective to provide cutouts such as the cutouts 56h and 56i according to the arrangement of the coil and the imaging device.

<Fourth Embodiment>
In the shielding members 56S, 56T, and 56U described above, the upright curved surface portions 56b and 56c are provided along the two side walls facing the coils 53a to 53c in the imaging device 6. As shown in FIG. However, it may be difficult to provide both of the bent surfaces 56b and 56c. In such cases, it is desirable to provide the bent surfaces in the direction in which the influence of the leakage of the magnetic field from the coil to the imaging device 6 is relatively large.

The direction in which the influence of the leakage of the magnetic field to the imaging device 6 is large can be specifically determined as follows. For example, consider a posture (normal posture) in which the X-axis and Z-axis are substantially parallel to the horizontal direction and the Y-axis is substantially parallel to the vertical direction, which is defined for the imaging device as shown in FIG. 1(a). If the motion compensation unit 14 is driven while the image pickup apparatus is in the normal posture, it is necessary to apply a larger current to the coils 53a and 53b than to the coil 53c in order to support the weight of the movable portion 50 itself. As a result, the magnetic fields generated by the coils 53a and 53b are increased, and the influence of the leakage of the magnetic field to the imaging element 6 from the coils 53a and 53b is greater than that from the coil 53c. In addition, when a photographer uses an image pickup apparatus, it is considered that the user most often uses the normal posture. Therefore, when the image pickup apparatus is in the normal posture, the side of the coils 53a and 53b that is most affected by the leakage of the magnetic field to the image pickup device 6 is the side of the coils 53a and 53b.

Due to the following problems, it may be difficult to provide the shielding members 56S, 56T, and 56U with both the upright curved surface portions 56b and 56c. For example, the shielding member 56S having the raised curved surface portions 56b and 56c should be arranged such that the raised curved surface portions 56b and 56c are both spread toward the imaging element 6 when unfolded into a flat plate shape before bending, and that the raised curved surface portions 56b and 56c do not interfere with each other in the unfolded state. Therefore, it may not be possible to form the standing bent surface portions 56b and 56c into a desired shape. In that case, it is desirable to provide the standing bent surface portion only on the side of the coil that is more affected by the leakage of the magnetic field into the imaging device 6 . Another problem is to reduce the weight of the movable part 50. In this case, too, only the side of the coil that is more affected by the leakage of the magnetic field into the imaging device 6 should be provided with the upright bending surface.

Further, in the movable portion 50A, by controlling the direction of the current flowing through the coils 53a and 53b, a driving force is generated for moving in the rotational direction and the translational direction about the axis parallel to the optical axis. Therefore, the bending surface portion 56c provided between the coils 53a and 53b and the imaging device 6 may be provided preferentially over the bending surface portion 56b provided between the coil 53c and the imaging device 6. FIG. In other words, when the two coils 53a and 53b are arranged close to each other and currents flow simultaneously, the magnetic fields generated from the coils 53a and 53b may be combined to form a large magnetic field depending on the direction of the current flowing through the coils 53a and 53b. Therefore, in a configuration such as the shake correction unit 14A that includes the coils 53a to 53c and that the coils 53a and 53b are arranged to face one side of the imaging element 6 and are driven simultaneously, it is desirable to provide at least the coils 53a and 53b side bent surface portion 56c.

Furthermore, in a configuration including a plurality of coils, the direction in which the influence of magnetic field leakage to the imaging device 6 is large may be determined based on the distance between the imaging device 6 and each coil. For example, since the influence of a magnetic field is inversely proportional to the distance, a magnetic field generated by a coil at a short distance from the imaging device 6 has a greater influence on the imaging device 6 than a magnetic field generated from a coil at a long distance from the imaging device 6. Therefore, it is desirable to provide the upright bending surface portion on the side of the coil arranged relatively close to the imaging device 6 . In addition, since the magnitude of the magnetic field generated from the coil can be inferred from the number of turns of the coil windings, the magnitude of the current flowing through the coil, and the like, the direction in which the leakage of the magnetic field to the imaging element 6 has a large effect may be determined based on these.

Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various forms without departing from the scope of the present invention are also included in the present invention. Furthermore, each embodiment described above merely shows one embodiment of the present invention, and it is also possible to combine each embodiment as appropriate.

1 camera body 3 photographic optical system 5 camera system control unit 6 image sensor 14, 14A, 14B, 14C blur correction unit 50, 50A, 50B movable part 53a to 53c coil 54a to 54c magnetic sensor 56, 56S, 56T, 56U shielding member 56b, 56c standing bending surface 56d, 56e, 56h, 56i Notch portion 60 Upper surface fixing portion 62a to 62f Magnet 70 Lower surface fixing portion 76a to 76f Magnet

Claims (10)

A blur correction device having a movable part having an image sensor and a fixed part movably supporting the movable part, wherein the image sensor is movable within a plane parallel to a light receiving surface of the image sensor,
The movable part is
one or more coils;
a holding member that holds the coil;
a plate-shaped first shielding portion made of a non-magnetic metal and arranged on the surface of the holding member opposite to the surface on which the coil is mounted;
a second shielding part made of a non-magnetic metal and arranged along a side wall of the imaging element facing the coil side,
The fixed part is
A permanent magnet arranged at a position facing the coil,
When viewed from a direction perpendicular to the light receiving surface of the image pickup device, the first shield covers at least a portion of the coil, and the hollow portion of the coil and the center of the permanent magnet overlap in a first direction parallel to the light receiving surface of the image pickup device. A blur correction device characterized by: The imaging element and the coil are arranged substantially on the same plane,
2. The blur correction device according to claim 1, wherein the axial direction of the hollow portion of the coil is substantially parallel to the direction orthogonal to the light receiving surface. 3. The blur correction device according to claim 1, wherein the first shielding part covers at least the hollow part of the coil when viewed from a direction orthogonal to the light receiving surface of the image sensor. 4. The blur correction device according to claim 1, wherein the gap is formed on a plane portion parallel to the light receiving surface of the image sensor. a plurality of said coils;
and a plurality of the permanent magnets facing the plurality of coils,
The blur correction device according to any one of claims 1 to 4 , wherein the second shielding section is provided between one of the plurality of coils that is more affected by the generated magnetic field and the imaging device. a plurality of said coils;
and a plurality of the permanent magnets facing the plurality of coils,
The blur correction device according to any one of claims 1 to 4 , wherein the second shielding section is provided between the coil and the imaging element that generate a driving force that translates the imaging element in a vertical direction with the light receiving surface of the imaging element substantially parallel to the vertical direction. a plurality of said coils;
and a plurality of the permanent magnets facing the plurality of coils,
The blur correction device according to any one of claims 1 to 4 , wherein the second shielding unit is provided between two coils of the plurality of coils that generate a driving force that translates the imaging element in the plane and a driving force that rotates the imaging element about an axis perpendicular to the light receiving surface and the imaging element. 8. The blur correction device according to claim 1, further comprising a magnetic sensor disposed on said holding member within a hollow portion of said coil. 9. The blur correction device according to claim 1, wherein said holding member is a flexible printed circuit board having flexibility. An imaging apparatus comprising the blur correction device according to any one of claims 1 to 9 .