Blur correction device

Abstract

One aspect according to the technology of the present disclosure provides a blur correction device which moves a holding member for holding an imaging element to correct blur. A blur correction device according one aspect of the present invention comprises: a fixed part provided with a magnet member and a yoke member; and a movable part which comprises a holding member for holding an imaging element and a first coil member and in which the holding member is movably supported, wherein the magnet member includes a first magnet and a second magnet, and a first width which is the width of the first magnet is greater than a second width which is the width of the second magnet.

Description

Image stabilization device

[0001] The present invention relates to a vibration reduction device for correcting vibration in an imaging device.

[0002] With regard to techniques for correcting shake in an imaging device, for example, Patent Documents 1 to 3 disclose image stabilization mechanisms that include a fixed portion, a movable portion, a yoke, a coil, and the like.

[0003] JP 2021-139949 A JP 2019-191405 A JP 2012-242768 A

[0004] One embodiment of the technique of the present disclosure provides a shake correction device that corrects shake by moving a holding member that holds an imaging element.

[0005] A first aspect of the present invention provides a vibration reduction device comprising: an imaging element; a fixed portion including a magnet member and a yoke member; a movable portion including a holding member that holds the imaging element and a first coil member, the holding member being movably supported; and the magnet member including a first magnet and a second magnet, and a first width that is the width of the first magnet being wider than a second width that is the width of the second magnet.

[0006] The image stabilization device according to the second aspect of the present invention is the first aspect, wherein the first width is the length of the shorter side of the outer shape of the first magnet, and the second width is the length of the shorter side of the outer shape of the second magnet.

[0007] A vibration reduction device according to a third aspect is the first or second aspect, wherein the ratio of the first magnetic flux density, which is the magnetic flux density of the first magnet, to the second magnetic flux density, which is the magnetic flux density of the second magnet, falls within a predetermined range.

[0008] A fourth aspect of the image stabilizer is the third aspect, wherein the first width and the second width are widths corresponding to a predetermined range.

[0009] A motion compensation device according to a fifth aspect is the motion compensation device of the third or fourth aspect, wherein the first magnet and the second magnet are made of the same material.

[0010] A sixth aspect of the image stabilization device is the image stabilization device of any one of the first to fifth aspects, wherein the first magnet is disposed closer to the imaging element than the second magnet.

[0011] The image stabilization device of the seventh aspect is the sixth aspect, in which the first magnet is positioned in an area where the first distance, which is the distance between the first magnet and the imaging element, is shorter than the second distance, which is the distance between the second magnet and the imaging element.

[0012] The image stabilization device according to the eighth aspect is any one of the first to seventh aspects, in which the yoke member includes a first yoke connected to the magnet member and a second yoke, the second yoke being arranged on the opposite side of the magnet member across the first coil member, and the first area in which the second yoke covers the first magnet being smaller than the second area in which the second yoke covers the second magnet.

[0013] The image stabilization device of the ninth aspect is the eighth aspect, wherein the first region is the region where the second yoke and the first magnet overlap when the first magnet is viewed from the side of the second yoke, and the second region is the region where the second yoke and the second magnet overlap when the second magnet is viewed from the side of the second yoke.

[0014] A motion compensation device according to a tenth aspect is the eighth or ninth aspect, wherein the difference between the size of the first region and the size of the second region is changed according to the amount of movement of the movable portion.

[0015] A vibration reduction device according to an eleventh aspect is the vibration reduction device of the eighth or ninth aspect, wherein the first magnet and the second magnet are a pair of magnets whose magnetic poles are arranged in opposite directions.

[0016] A motion compensation device according to a twelfth aspect is any one of the first to tenth aspects, wherein a magnetic circuit is formed by the first magnet, the second magnet, and the movable part.

[0017] A thirteenth aspect of the invention is a motion compensation device according to the twelfth aspect, wherein the movable part is moved within a plane parallel to the imaging surface of the imaging element by using a magnetic circuit and a current flowing through the first coil member.

[0018] A vibration reduction device according to a fourteenth aspect is any one of the first to thirteenth aspects, further comprising a biasing member that biases the movable portion toward the fixed portion.

[0019] A fifteenth aspect of the image stabilizer is any one of the first to fourteenth aspects, wherein when the second width is 1, the first width is 1.2 or more and 1.3 or less.

[0020] A sixteenth aspect of the invention is the image stabilizer of any one of the third to fifth aspects, wherein the first magnetic flux density is equal to or greater than 1.00 and equal to or less than 1.025 when the second magnetic flux density is taken as 1.

[0021] The image stabilizer according to a seventeenth aspect is any one of the eighth to tenth aspects, wherein the thrust of the movable part at the end of the range of motion of the second yoke is reduced compared to the thrust of the movable part at the center of the range of motion.

[0022] A motion compensation device according to an eighteenth aspect is the seventeenth aspect, wherein the degree of decrease is 20% or less.

[0023] The image stabilization device of the 19th aspect is any one of the first to eighteenth aspects, in which the holding member further holds a second coil member, the first coil member is a coil member for moving the movable part in a first direction, and the second coil member is a coil member for moving the movable part in a second direction intersecting the first direction.

[0024] A twentieth aspect of the image stabilizer is the nineteenth aspect, wherein the second coil member has a first end portion closer to the imaging element and a second end portion farther from the imaging element, each having a different shape.

[0025] A twenty-first aspect of the image stabilizer is the twentieth aspect, wherein the second end is narrower than the first end.

[0026] A motion compensation device according to a twenty-second aspect is any one of the nineteenth to twenty-first aspects, wherein at least a magnetic sensor is provided inside the second coil member.

[0027] The image stabilization device according to the 23rd aspect is any one of the 19th to 22nd aspects, wherein the holding member has a recess in the first holding portion that is far from the imaging element, in the holding portion that holds the first coil member and the second coil member.

[0028] FIG. 1 is a schematic diagram of the interior of an imaging device equipped with a vibration reduction device. FIG. 2 is a block diagram showing an embodiment of the internal configuration of the imaging device. FIG. 3 is a front perspective view of the vibration reduction device. FIG. 4 is a rear perspective view of the vibration reduction device. FIG. 5 is a front perspective view of a fixing unit. FIG. 6 is a front perspective view showing the arrangement of magnets. FIG. 7 is a front perspective view showing the arrangement of magnets, coils, imaging elements, and a holding frame. FIG. 8 is a partial perspective view showing the arrangement of yokes, coils, and magnets. FIG. 9 is a view showing the arrangement of yokes and magnets. FIG. 10 is another view showing the arrangement of yokes and magnets. FIG. 11 is yet another view showing the arrangement of yokes and magnets. FIG. 12 is a view showing how thrust decreases at the end of the movable range. FIG. 13 is a view showing the relationship between the amount of movement and the amount of cutout in the yoke. FIG. 14 is a view showing the relationship between the amount of movement and thrust when the ratio between the first width and the second width is changed. FIG. 15 is a view showing the relationship between the ratio of the magnet widths and the ratio of magnetic flux density. FIG. 16 is a view showing the arrangement of a deformed coil. Fig. 17 is a diagram showing how a movable part is biased by a biasing member, Fig. 18 is a diagram showing how an irregular-shaped coil is used in combination with a recess in a coil holding frame, and Fig. 19 is a diagram showing the connection point between the coil and the holding frame.

[0029] Preferred embodiments of the image stabilization device according to the present invention will now be described with reference to the accompanying drawings. In the drawings, in order to make the description easier to understand, some components may be omitted and / or the colors or line types of the components may be changed.

[0030] [Configuration of Imaging Apparatus] First, an imaging apparatus incorporating a motion compensation device will be described. Fig. 1 is a schematic diagram of the inside of an imaging apparatus incorporating a motion compensation device of the present invention.

[0031] The imaging device 10 is an interchangeable lens camera, and a photographic lens device 12 is attached to an imaging device body 2 via an adapter 6. The photographic lens device 12 includes an aperture 8 and lens groups 12A and 12B. The photographic lens device 12, which has an optical axis L, forms an image using light reflected from a subject 1. The imaging device body 2 includes an eyepiece 4, and a photographer can photograph the subject 1 by placing their eye on the eyepiece 4.

[0032] Image sensor 16 has a light receiving surface (imaging surface) arranged along a plane (X-Y plane) formed by two directions (X direction and Y direction) orthogonal to optical axis L (Z direction) of image sensor body 2. Image sensor 16 is held by image stabilization device 100. Furthermore, a drive unit 58 included in image stabilization device 100 is controlled by control unit 40, thereby realizing the image stabilization function.

[0033] 2 is a block diagram showing an embodiment of the internal configuration of the imaging device 10. This imaging device 10 records captured images on a memory card 54, and the operation of the entire device is centrally controlled by a control unit 40 including a processor such as a CPU (Central Processing Unit).

[0034] The imaging device 10 is provided with an operation unit 38 including a shutter button, a power / mode switch, a mode dial, a cross button, etc. Signals (commands) from this operation unit 38 are input to a control unit 40, which controls each circuit of the imaging device 10 based on the input signals, and performs drive control of the imaging element 16, lens drive control, aperture drive control, imaging operation control, image processing control, image data recording / playback control, and display control of the image monitor 30.

[0035] The light beam passing through the photographing lens device 12 forms an image on the image sensor 16, which is a CMOS (Complementary Metal-Oxide Semiconductor) color image sensor. The image sensor 16 is not limited to the CMOS type, and other types of image sensors such as a CCD (Charge Coupled Device) type or an organic image sensor may also be used.

[0036] The image sensor 16 has a large number of light-receiving elements (e.g., photodiodes) arranged two-dimensionally, and the subject image formed on the light-receiving surface of each light-receiving element is converted (photoelectrically converted) into a signal voltage (or charge) of an amount corresponding to the amount of incident light, and then converted into a digital signal via an A / D (Analog / Digital) converter within the image sensor 16 and output.

[0037] Image signals (image data) read from the image sensor 16 when capturing a moving image or a still image are temporarily stored in a memory 48 (for example, a Synchronous Dynamic Random Access Memory (SDRAM)) via an image input controller 22 .

[0038] Furthermore, a flash memory 47 stores a camera control program and various parameters and tables used for image processing and the like.

[0039] The sensor 66 is a camera shake sensor that detects attitude information and attitude change information of the imaging device 10. The sensor 66 is configured, for example, with a gyro sensor. The sensor 66 is configured, for example, with two gyro sensors for detecting the amount of camera shake in the vertical direction (+Y, −Y directions) and the horizontal direction (+X, −X directions), and the detected amounts of camera shake (angular velocity) are input to the control unit 40. The control unit 40 controls the drive unit 58 to perform shake correction by moving the image sensor 16 so as to cancel movement of the subject image caused by camera shake. A gyro sensor for detecting the amount of camera shake in a rotational direction (for example, around the Z axis) may be provided in the sensor 66, and shake correction may be performed to cancel camera shake in this rotational direction.

[0040] The driving unit 58 (driving mechanism) is controlled by the control unit 40. The driving unit 58 is configured by a voice coil motor (VCM) (to be described later) and the like.

[0041] The image processing unit 24 reads unprocessed image data that is acquired via the image input controller 22 when capturing moving images or still images and that is temporarily stored in the memory 48. The image processing unit 24 performs offset processing, pixel interpolation processing (interpolation processing for phase difference detection pixels, defective pixels, etc.), white balance correction, gain control processing including sensitivity correction, gamma correction processing, synchronization processing (also called "demosaic processing"), luminance and color difference signal generation processing, contour enhancement processing, color correction, etc. The image data that has been processed by the image processing unit 24 and that has been processed as a live view image is input to a VRAM (Video RAM Random Access Memory) 50.

[0042] The image data read from the VRAM 50 is encoded by the video encoder 28 and output to the image monitor 30 provided on the rear surface of the camera. As a result, a live view image showing the subject image is displayed on the image monitor 30.

[0043] The image data (brightness data (Y) and color difference data (Cb), (Cr)) processed by the image processing unit 24 as a still image or a moving image for recording is stored again in the memory 48.

[0044] When recording a still image or a moving image, the compression / decompression processing unit 26 performs compression processing on the luminance data (Y) and color difference data (Cb), (Cr) that have been processed by the image processing unit 24 and stored in the memory 48. The compressed image data is recorded on a memory card 54 via a media controller 52.

[0045] In addition, in the playback mode, the compression / decompression processing unit 26 performs decompression processing on compressed image data obtained from the memory card 54 via the media controller 52. The media controller 52 records and reads compressed image data onto and from the memory card 54.

[0046] In the above embodiment, the hardware structure of a processing unit such as the control unit 40 that executes various processes is the following various processors: The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) to function as various processing units, a programmable logic device (PLD), such as an FPGA (Field Programmable Gate Array), whose circuit configuration can be changed after manufacture, and a dedicated electrical circuit, such as an ASIC (Application Specific Integrated Circuit), which is a processor with a circuit configuration designed specifically for executing specific processes.

[0047] A single processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types (e.g., multiple FPGAs, or a combination of a CPU and an FPGA). Multiple processing units may also be configured with a single processor. Examples of multiple processing units configured with a single processor include: a first configuration, as typified by client or server computers, in which a single processor is configured with a combination of one or more CPUs and software, and this processor functions as multiple processing units; and a second configuration, as typified by system-on-chip (SoC), in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip. In this way, the various processing units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0048] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit made up of a combination of circuit elements such as semiconductor elements.

[0049] [Overview of Image Stabilization Device] Next, an overview of image stabilization device 100 will be described. FIGS. 3 to 8 are diagrams showing image stabilization device 100 mounted on image capture device 10. FIG. 3 is a front perspective view of image stabilization device 100, FIG. 4 is a rear perspective view of image stabilization device 100, and FIG. 5 is a front perspective view of fixed portion 102. FIG. 6 is a front perspective view showing the arrangement of magnets, FIG. 7 is a front perspective view showing the arrangement of magnets, coils, image sensors, and holding frames, and FIG. 8 is a partial perspective view showing the arrangement of yokes, coils, and magnets. In the following description, "front" refers to the surface seen from the +Z side (subject side), and "rear" refers to the surface seen from the -Z side (photographer side).

[0050] The image stabilization device 100 is primarily composed of a movable part 101 (movable part) on which the image sensor 16 (image sensor) is mounted, and a fixed part 102 (fixed part) that is fixed to the image sensor body 2. The movable part 101 abuts against the fixed part 102 via a ball (not shown). The movable part 101 is also urged toward the first yoke 105 (fixed part 102) by the urging force of a magnetic spring plate 120 (urging member; see FIGS. 11 and 17 ), which will be described later, and the ball is sandwiched between the movable part 101 and the fixed part 102. The movable part 101 can move and / or rotate within a plane (X-Y plane) perpendicular to the optical axis L (Z-axis), i.e., within a plane parallel to the imaging surface of the image sensor 16.

[0051] [Structure of the Fixed Section] The fixed section 102 is composed of a first yoke 105 (yoke member, first yoke) and a second yoke 103 (yoke member, second yoke), and is fixed to the imaging device body 2 by a mechanism not shown. The first yoke 105 is disposed on the photographer side (-Z side), and the second yoke 103 is disposed on the subject 1 side (+Z side). The first yoke 105 is disposed at a position facing and spaced apart from the second yoke 103 by shafts 121, 123, and 125. These shafts also function as movable end stoppers on the fixed section 102 side.

[0052] The first yoke 105 is connected to magnet 113b (magnet members: first magnet, second magnet), magnet 115b, magnet 117b, and magnet 119, and the second yoke 103 is disposed on the opposite side of these magnets (magnet members) across coils such as coil 113a (first coil member). As will be described in detail later, these magnets include a pair of magnets with magnetic poles arranged in opposite directions.

[0053] As shown in FIGS. 6 and 7 , the magnet 113b and the coil 113a provided in the movable part 101 constitute a voice coil motor 113 (VCM). The magnet 115b and the coil 115a provided in the movable part 101 constitute a voice coil motor 115 (VCM). The magnet 117b and the coil 117a provided in the movable part 101 constitute a voice coil motor 117 (VCM). The magnets 115b, 117b, and 119 are also used as magnets for a Hall element (magnetic sensor) that detects the position of the movable part 101. The magnet 113b is a magnet dedicated to the voice coil motor 113. The voice coil motor 113, the voice coil motor 115, and the voice coil motor 117 constitute a drive unit 58 (see FIGS. 1 and 2 ).

[0054] 7, the movable part 101 includes a holding frame 101a (holding member). The holding frame 101a holds the imaging element 16, the coil 113a, the coils 115a, 117a, etc., and is movably supported by the balls or the like.

[0055] [Magnetic Circuit] Coil 113a (first coil member) is a coil member for moving movable part 101 (movable part) in the +Y direction or the −Y direction (first direction), and coil 115a and coil 117a (second coil member) are coil members for moving movable part 101 (movable part) in the X direction (+X direction, −X direction: second direction) that is perpendicular (one aspect of intersection) to the Y direction (+Y direction, −Y direction). Furthermore, magnet 113b (first magnet, second magnet), magnet 115b, magnet 117b, and magnet 119 described above comprise a pair of magnets whose magnetic poles are arranged in opposite directions, and these magnets and movable part 101 form a magnetic circuit (a closed circuit containing magnetic flux). This magnetic circuit also includes voice coil motors 113, 115, and 117, as well as a magnetic spring plate 120 (see FIGS. 11 and 17), which will be described later.

[0056] Note that "a pair of magnets with magnetic poles arranged in opposite directions" means, for example, that one of the pair of magnets constituting magnets 113b, 115b, 117b, and 119 is arranged with its north pole on the +Z side and the other magnet is arranged with its south pole on the +Z side, with magnetic field lines pointing from the north pole to the south pole. Specifically, as shown in FIG. 6 , magnet 113b includes a pair of magnets, 113b1 (first magnet) and 113b2 (second magnet). In FIG. 6 , magnet 113b1 can be arranged with its south pole on the +Z side and magnet 113b2 with its north pole on the +Z side. Magnet 113b1 is arranged closer to image sensor 16 than magnet 113b2. Magnet 113b1 has a width w1 (first width; the length of the shorter side of the outer shape of magnet 113b1), and magnet 113b2 has a width w2 (second width; the length of the shorter side of the outer shape of magnet 113b2). Similarly, magnet 115b can be arranged so that magnet 115b1 has an S pole on the +Z side and magnet 115b2 has an N pole on the +Z side, magnet 117b can be arranged so that magnet 117b1 has an S pole on the +Z side and magnet 117b2 has an N pole on the +Z side, and magnet 119 can be arranged so that magnet 119b1 has an S pole on the +Z side and magnet 119b2 has an N pole on the +Z side. Note that the orientation of these magnets is an example, and magnets may be arranged in the opposite direction to the above-mentioned orientation.

[0057] Furthermore, magnet 113b1 (first magnet) is disposed closer to image sensor 16 than magnet 113b2 (second magnet). Specifically, magnet 113b1 is disposed in an area where a first distance (the distance in the Y direction in FIG. 6 ), which is the distance between magnet 113b1 and image sensor 16, is shorter than a second distance (the distance in the Y direction in FIG. 6 ), which is the distance between magnet 113b2 and image sensor 16.

[0058] [Movement and Rotation of Movable Part by Magnetic Circuit] The movable part 101 can be moved in a plane parallel to the imaging surface of the imaging element 16 (in the X-Y plane) using the above-described magnetic circuit and currents flowing through the coils (coils 113a, 115a, 117a). Furthermore, by changing the amount of drive in the X-axis direction (+X direction or −X direction) by the voice coil motor 115 and the amount of drive in the X-axis direction (+X direction or −X direction) by the voice coil motor 117, the movable part 101 can be rotated in a plane parallel to the imaging surface of the imaging element 16 (around the Z axis). When camera shake or the like occurs, the movable part 101 is driven by the voice coil motors 113, 117, and 115 in a direction that cancels out the camera shake, thereby suppressing the effects of camera shake on the image captured by the imaging element 16 mounted on the movable part 101.

[0059] The movable part 101 has a ball receiving portion (not shown) for receiving the above-mentioned ball on the surface facing the first yoke 105. The ball receiving portion is movable as the ball rolls, and this allows the movable part 101 to freely move and / or rotate (rotate around the Z axis) on a plane (X-Y plane) perpendicular to the optical axis L (i.e., within a plane parallel to the imaging surface of the imaging element 16). The first yoke 105 has a ball receiving surface (not shown) on the fixed part 102 side.

[0060] With regard to the arrangement of the devices in image stabilization device 100 and the movement of movable part 101, the Y-axis direction may be described as the "up-down direction" (the +Y direction is "up" and the -Y direction is "down"), and the X-axis direction may be described as the "left-right direction" (the +X direction is "right" and the -X direction is "left").

[0061] [Motion Picture Stabilization Device Details] [Miniaturizing the Actuator and Ensuring Thrust Force] In recent years, there has been a demand for compact, lightweight, and high-performance cameras. While cameras are required to incorporate large, high-pixel image sensors (e.g., CMOS) and motion stabilization devices, miniaturization of the motion stabilization device is also necessary to minimize their configuration and size. Motion stabilization devices have an actuator and a sensor to correct camera shake by moving and / or rotating the image sensor. The actuator may be, for example, a voice coil motor (VCM), and the sensor may be, for example, a magnetic sensor (e.g., a Hall element). Because the size of the magnetic circuit containing the VCM and magnetic sensor determines the size of the motion stabilization device, optimizing the layout of components to achieve miniaturization is important. Sharing the magnetic circuit between the VCM and magnetic sensor can achieve miniaturization, and arranging magnetic circuit components above and below the image sensor can reduce the size of the side of the image sensor. Creating space on the side of the image sensor allows for denser placement of other units, leading to a more compact camera.

[0062] However, miniaturizing the magnetic circuit tends to reduce the thrust of the VCM and the position detection accuracy of the magnetic sensor. Therefore, to achieve both the required magnetic circuit performance and compactness, a meticulous magnetic circuit design is preferable. To avoid magnetic interference between the magnetic circuit and the shutter motor around the image stabilization device and prevent a decrease in thrust, it is desirable to arrange the VCM as follows: One VCM component for vertical drive (voice coil motor 113) is located on the opposite side (+Y side) of the shutter motor (not shown), and one VCM component for horizontal drive (voice coil motors 115, 117) is located on the top (+Y side of the −X side) and the bottom (−Y side of the −X side), as shown in FIGS. 6 and 7 . To increase the thrust, it is desirable to have a circuit with a high magnetic flux density in which the pair of magnets in the fixed part 102, the coil in the movable part 101, and the yoke (first yoke 105, second yoke 103) in the fixed part 102 overlap in the optical axis direction; however, if the magnetic circuit is made smaller, it becomes unavoidable to have a notch in the second yoke 103 on the imaging element 16 side to avoid mechanical interference with the movable part 101.

[0063] [Cutout in Yoke and Asymmetrically Shaped Magnet] Figures 9 to 11 are diagrams showing the arrangement of the yoke and magnet. In the image stabilization device 100 according to this embodiment, as shown in Figures 9 to 11, a cutout portion 103a is provided in the second yoke 103, and a first region 103b (first region) in which the second yoke 103 covers the magnet 113b1 (first magnet) is smaller than a second region 103c (second region) in which the second yoke 103 covers the magnet 113b2 (second magnet). As shown in Figure 10, the first region 103b is the region where the second yoke 103 and the magnet 113b1 overlap when the magnet 113b1 (first magnet) is viewed from the side of the second yoke 103 (+Z direction), and the second region 103c is the region where the second yoke 103 and the magnet 113b2 overlap when the magnet 113b2 is viewed from the side of the second yoke 103 (+Z direction).

[0064] Therefore, the magnetic flux density is high on the magnet 113b2 side (e.g., the north pole side) because the magnet and second yoke 103 overlap in the optical axis direction, while the magnetic flux density is low on the magnet 113b1 side (e.g., the south pole side) because of the notch 103a. Because of the difference in magnetic flux density between the north pole side and the south pole side, the thrust in the vertical direction (Y direction) becomes unbalanced and asymmetric, resulting in a decrease in thrust at the end of the range of motion of the second yoke 103 (second yoke) compared to the thrust at the center of the range of motion (also known as "thrust drop"). For example, as shown in FIG. 12 , the thrust at the end of the range of motion (near the right end of the graph) is 30% or more lower than the thrust at the center of the range of motion (where the amount of movement is 0). This decrease in thrust makes it impossible to control the moving parts, and image stabilization becomes ineffective.

[0065] The design size of the image stabilization device is determined by the area obtained by subtracting the peripheral units from the target size of the camera, and this also determines the design size area of ​​the pair of magnets and yoke of fixed part 102. The cutout in the yoke is determined by the amount of movement, and as shown in Figure 13, the cutout amount increases linearly as the amount of movement increases (the difference in size between first area 103b and second area 103c changes depending on the amount of movement of movable part 101).

[0066] [Magnetic Flux Density Ratio and Magnet Width] To design a VCM with minimal reduction in thrust within its range of motion even with a notch in the yoke, it is desirable to optimally combine the width w1 (first width) of magnet 113b1 (first magnet) and the width w2 (second width) of magnet 113b2 (second magnet) with the size of second yoke 103 so that the magnetic flux densities on the north and south pole sides are as equal as possible within the specified magnet and yoke widths. To simultaneously prevent thrust reduction and maximize thrust, it is even more desirable to design the magnet width and yoke width to be as wide as possible within the specified design size range. By designing the magnet width, which is the sum of the first width and the second width, and the yoke width to be the maximum width and maximizing the overlapping area to maximize thrust, while designing magnet 113b to have an asymmetric shape such that "width w1 of magnet 113b1 > width w2 of magnet 113b2" (the first width is wider than the second width), or in other words, by adjusting the magnet width so that the magnetic flux density on the magnet 113b1 side is equal to (or approximately the same as) the magnetic flux density on the magnet 113b2 side, it is possible to design a VCM that has little reduction in thrust at the ends of the range of motion (for example, when comparing the thrust at the ends of the range of motion with the thrust at the center, the degree of reduction in thrust is 20% or less).

[0067] It is desirable to distribute the first and second widths so that the ratio of the magnetic flux density on the magnet 113b1 side to the magnetic flux density on the magnet 113b2 side falls within a predetermined range (the first and second widths are set to widths corresponding to the "predetermined range" of the magnetic flux density ratio). Figure 14 is a diagram showing the relationship between the movable amount and thrust force when the ratio of the first width to the second width is changed, and each curve in the diagram shows the thrust force when the ratio of the first width to the second width is changed. From Figure 14, it can be seen that changing the ratio of the first width to the second width also changes the degree of thrust force reduction at the ends of the movable range (near the ends of the graph).

[0068] Fig. 15 shows the relationship between the ratio of the magnet widths and the ratio of the magnetic flux densities. Fig. 15 shows that in order to ensure that the ratio of the magnetic flux density (first magnetic flux density) on the magnet 113b1 side to the magnetic flux density (second magnetic flux density) on the magnet 113b2 side (first magnetic flux density when the second magnetic flux density is 1) is 1.00 or more and 1.025 or less (an example of a "predetermined range"), it is preferable to set the ratio of the first width to the second width (first width / second width) to 1.2 or more and 1.3 or less (a ratio corresponding to the range of the magnetic flux density ratio). It is even more preferable to set the ratio of the first width to the second width close to 1.25.

[0069] In this way, by providing the cutout portion 103a in the second yoke 103 and making the "first width > second width" (using a combination of an asymmetrically shaped yoke and an asymmetrically shaped magnet), it is possible to ensure both the necessary thrust and the miniaturization of the imaging device. Note that, in the above-described embodiment, it is assumed that the material of the magnet 113b1 (first magnet) and the magnet 113b2 (second magnet) is the same, but the ratio of the magnetic flux densities may be changed by changing the material of the magnets, or the ratio of the magnetic flux densities may be changed by combining a change in shape and a change in material.

[0070] [Use of Irregularly Shaped Coils] In addition to the asymmetrical combination described above, further miniaturization can be achieved by sharing a pair of magnets in the fixed section between the VCM and the Hall element magnetic circuits. Furthermore, further miniaturization can be achieved by arranging three elements inside the coil: a Hall element (magnetic sensor), a thermistor, and a land on a flexible board to which the coil winding is soldered. For example, as shown in FIG. 16, it is preferable to arrange a thermistor 116a, a Hall element 116b (one form of magnetic sensor), and a land 116c inside the coil 117a (second coil member). Of these three elements, it is preferable to arrange at least the Hall element (magnetic sensor) inside the coil. This arrangement is also true for the coil 115a (second coil member).

[0071] It is desirable to reduce the coil's external dimensions while maintaining the minimum internal coil size required to accommodate the above three elements. However, this trade-off comes with a reduction in thrust force due to the reduced coil size. Therefore, by changing the coil shape from a rectangular shape (such as an oval or other symmetrical shape) to an irregular (asymmetrical) shape, a VCM can be designed that minimizes thrust force reduction (e.g., a thrust force reduction of 10% or less across the entire range of motion) while still achieving a reduced size. Specifically, it is desirable to make the end of the second coil member farther from the imaging element 16 irregular in shape (the second coil member has different shapes between a first end close to the imaging element and a second end farther from the imaging element). For example, as shown in FIG. 16 , it is preferable that the end 118b (second end) of the coil 117a (second coil member) farther from the imaging element 16 be narrower than the end 118a (first end) closer to the imaging element. This is because the end farther from the imaging element 16 has a greater impact on the size of the image stabilization device than the end closer to the imaging element 16. Similarly, it is preferable to use such an irregularly shaped coil for the coil 115a (second coil member).

[0072] By adjusting the size in the optical axis direction, such as by increasing the height of the magnet (height in the Z direction) or narrowing the gap between the coil and the magnet to compensate for the decrease in thrust, it is possible to ensure the necessary thrust while also miniaturizing the imaging device.

[0073] [Biasing of Movable Part] In addition to the configuration described above, in order to reduce the size of the image stabilization mechanism, it is desirable to urge the movable part 101 toward the fixed part 102 using a magnetic urging member. If the magnet of the fixed part 102 and the coil and urging member of the movable part 101 are arranged overlapping in the optical axis direction by sharing the magnetic circuit of the VCM, Hall element, etc., the image stabilization device 100 can be reduced in size. Figure 17 is a diagram showing an example in which the movable part 101 is urged toward the first yoke 105 of the fixed part 102 by magnetic spring plates 120 (an example of a urging member) (the number of magnetic spring plates 120 is one example).

[0074] [Combination of Irregularly Shaped Coils and Recesses in Coil Holding Frames] The coils (coils 113a, 115a, 117a) are assembled to a holding frame 101a (holding member) that holds the image sensor 16. By drilling holes in the holding frame 101a that correspond to the coil's outer shape and bonding and fixing them with a UV-curable (UV: Ultra Violet) adhesive, the moving part 101 can be made smaller. The holding frame 101a is manufactured by die-casting, for example. However, further miniaturization is possible by manufacturing the holding frame 101a by resin molding and combining it with the irregularly shaped coil described above. As shown in FIG. 18 , by providing a recess 170 (recess or notch) in the portion of the holding frame 101a that holds the coils (holding portion) where the coils are irregularly shaped (first holding portion) (at the ends of the coils 115a and 117a farther from the image sensor 16), the image sensor 16 can be made smaller.

[0075] [Bonding the Coil and the Retaining Frame with a UV-Curing Adhesive] To prevent a decrease in the strength of the moving part due to the resin material and the large cutout portion and to ensure sufficient strength against creep due to dropping or magnetic attraction, it is desirable to bond the coils (coils 113a, 115a, 117a) and the retaining frame 101a with a UV-curing adhesive having a high Young's modulus (e.g., 150 MPa or higher) and a high glass transition point (e.g., 40°C or higher) to increase rigidity. Figure 19 (showing the retaining frame 101a shown in Figure 18 as viewed from the -Z side) is a diagram showing the bonding points (bonding areas 172) between the coil and the retaining frame using a UV-curing adhesive. Although the rigidity of the retaining frame 101a alone decreases due to the miniaturization achieved by providing the recess 170 in the retaining frame 101a, increasing the rigidity of the retaining frame 101a after coil bonding ensures the strength of the moving part 101, thereby suppressing performance changes in the VCM and the Hall element (magnetic sensor).

[0076] Although the above describes an embodiment of the present invention, the present invention is not limited to the above-described aspects and various modifications are possible. For example, in the above-described embodiment, the coil 115a and coil 117a (second coil member) for driving in the +X or −X direction are described as having irregular shapes. However, the coil 113a (first coil member) for driving in the +Y or −Y direction may also be irregularly shaped. Specifically, when the coil 113a is irregularly shaped, the width of the end on the +Y side may be narrowed, or the width of the end on the +X side or the −X side may be narrowed. Furthermore, a recess or notch may be provided in the holding frame 101a to match the shape of the irregular shape (depending on which end is narrowed). Specifically, a partial recess or notch may be provided in the portion of the holding frame 101a where the coil is irregularly shaped (for example, the end of the coil 113a farther from the imaging element 16). The type of irregular shape of the coil and the notch of the holding frame to be adopted can be determined based on "which side needs to be made smaller in relation to the device layout."

[0077] REFERENCE SIGNS LIST 1 Subject 2 Imaging device body 4 Eyepiece 6 Adapter 8 Aperture 10 Imaging device 12 Taking lens device 12A Lens group 16 Imaging element 22 Image input controller 24 Image processing section 26 Compression / expansion processing section 28 Video encoder 30 Image monitor 38 Operation section 40 Control section 47 Flash memory 48 Memory 52 Media controller 54 Memory card 58 Driving section 66 Sensor 100 Image stabilization device 101 Movable section 101a Holding frame 102 Fixed section 103 Second yoke 103a Notch section 103b First region 103c Second region 105 First yoke 107 Ball receiving section 113 Voice coil motor 113a Coil 113b Magnet 113b1 Magnet 113b2 Magnet 115 Voice coil motor 115a Coil 115b Magnet 115b1 Magnet 115b2 Magnet 116a Thermistor 116b Hall element 116c Land 117 Voice coil motor 117a Coil 117b Magnet 117b1 Magnet 117b2 Magnet 118a End 118b End 119 Magnet 119b1 Magnet 119b2 Magnet 120 Magnetic spring plate 121 Shaft 123 Shaft 125 Shaft 170 Recess 172 Adhesion area L Optical axis

Claims

1. An imaging element; a fixed portion including a magnet member and a yoke member; a movable section including a holding member that holds the imaging element and the first coil member, the holding member being movably supported by the movable section; A vibration reduction device comprising: the magnet member includes a first magnet and a second magnet, the first magnet and the second magnet are arranged in the same plane perpendicular to the optical axis of the imaging element, A shake correction device, wherein a first width, which is a width of the first magnet, is wider than a second width, which is a width of the second magnet.

2. the first width is the length of a shorter side of the outer shape of the first magnet, 2. The image stabilization device according to claim 1, wherein the second width is the length of a shorter side of the outer shape of the second magnet.

3. 3. The image stabilization device according to claim 1, wherein a ratio of a first magnetic flux density, which is the magnetic flux density of the first magnet, to a second magnetic flux density, which is the magnetic flux density of the second magnet, falls within a predetermined range.

4. The image stabilization device according to claim 3 , wherein the first width and the second width are widths corresponding to the predetermined range.

5. 4. The image stabilization device according to claim 3, wherein the first magnet and the second magnet are made of the same material.

6. 3. The image stabilization device according to claim 1, wherein the first magnet is disposed closer to the imaging element than the second magnet.

7. 7. The image stabilizer according to claim 6, wherein the first magnet is disposed in an area where a first distance between the first magnet and the imaging element is shorter than a second distance between the second magnet and the imaging element.

8. the yoke member includes a first yoke and a second yoke connected to the magnet member, the second yoke is disposed on the opposite side of the magnet member with the first coil member interposed therebetween, 3. The image stabilization device according to claim 1, wherein a first area where the second yoke covers the first magnet is smaller than a second area where the second yoke covers the second magnet.

9. the first region is a region where the second yoke and the first magnet overlap when the first magnet is viewed from the second yoke side, 9. The image stabilization device according to claim 8, wherein the second region is a region where the second yoke and the second magnet overlap when the second magnet is viewed from the second yoke side.

10. 9. The image stabilization device according to claim 8, wherein the difference between the size of the first area and the size of the second area is changed according to the amount of movement of the movable portion.

11. 3. The image stabilization device according to claim 1, wherein the first magnet and the second magnet are a pair of magnets whose magnetic poles are arranged in opposite directions.

12. 3. The image stabilization device according to claim 1, wherein the first magnet, the second magnet, and the movable portion form a magnetic circuit.

13. 13. The image stabilization device according to claim 12, wherein the movable portion is moved within a plane parallel to the imaging surface of the imaging element by using the magnetic circuit and the current flowing through the first coil member.

14. The image stabilization device according to claim 1 or 2, further comprising a biasing member that biases the movable portion toward the fixed portion.

15. 3. The image stabilization device according to claim 1, wherein the first width is equal to or greater than 1.2 and equal to or less than 1.3 when the second width is set to 1.

16. 4. The image stabilization device according to claim 3, wherein the first magnetic flux density is equal to or greater than 1.00 and equal to or less than 1.025 when the second magnetic flux density is set to 1.

17. 9. The vibration reduction device according to claim 8, wherein the thrust of the movable portion at the end of the movable range of the second yoke is lower than the thrust of the movable portion at the center of the movable range.

18. 18. The image stabilization device according to claim 17, wherein the degree of the decrease is 20% or less.

19. the holding member further holds a second coil member; 3. The image stabilization device according to claim 1, wherein the first coil member is a coil member for moving the movable part in a first direction, and the second coil member is a coil member for moving the movable part in a second direction intersecting the first direction.

20. 20. The image stabilizer according to claim 19, wherein the second coil member has a first end portion closer to the imaging element and a second end portion farther from the imaging element, the first end portion having a different shape from the second end portion.

21. 21. The image stabilization device according to claim 20, wherein the second end is narrower than the first end.

22. 20. The image stabilization device according to claim 19, wherein at least a magnetic sensor is provided inside the second coil member.

23. 20. The image stabilizer according to claim 19, wherein the holding member has a holding portion for holding the first coil member and the second coil member, the holding portion having a recess in a first holding portion farther from the imaging element.