Drive device, image blur correction device, and image capturing apparatus

Abstract

To provide a drive device compact in size and capable of moving with a large stroke while ensuring a required thrust.SOLUTION: An image blur correction unit 14 as a drive device includes: a fixed section; a movable section 200 holding an imaging element 6; a third coil 205c arranged in the movable section 200; and a third upper magnet section 103e and a third lower magnet section 1073 which are arranged so as to sandwich a third coil 205c with a predetermined gap in an optical axis direction. The movable section 200 is moved to a first direction orthogonal to the optical axis direction. When viewed from the optical axis direction, in the first direction, a distance from a photographing optical axis 4 to a polarization line 103N of the third upper magnet section 103e is different from a distance from the photographing optical axis 4 to a polarization line of the third lower magnet section 1073.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a drive unit including a magnet and a coil, and an image stabilization device and an imaging device that include the drive unit. [Background technology]

[0002] Imaging devices use various drive devices to drive optical components. Such drive devices are required to be capable of moving optical components with high precision and over a large stroke. Furthermore, to accommodate the increasing size and weight of optical components to be moved, drive devices that are small and have a large thrust are also required.

[0003] For example, the voice coil motor system is widely used in image stabilization devices that suppress image blur caused by camera shake or the like during image capture by shifting (displacing) an optical component (a lens or an image sensor) within a plane perpendicular to the optical axis. In the voice coil motor system, a coil is placed on either the movable part or the fixed part, and a magnet is placed on the other, and the movable part is moved relative to the fixed part by utilizing the interaction between the magnetic field generated by passing a current through the coil and the magnetic field of the magnet.

[0004] Image stabilization devices are required to be able to move optical components over a large stroke so that they can correct image blur even when significant camera shake occurs, and at the same time, they must ensure the necessary thrust when driven. Patent Document 1 discloses an image stabilization device with an improved magnet configuration for increasing thrust. Patent Document 1 discloses a configuration in which magnets are arranged on either side of a coil, thereby effectively increasing the magnetic flux that crosses the coil.

[0005] In order to move a movable part with high precision, it is often necessary to detect the amount of movement of the movable part, i.e., the position of the movable part. One example of a method for detecting the position of a movable part is a magnetic position detection method. This method uses a magnetic sensor, such as a Hall element or an MR (magnetoresistive) element, that outputs an electric signal according to a change in magnetic flux density, and detects the relative position between the magnet and the magnetic sensor based on the electric signal that changes with the relative movement between the magnet and the magnetic sensor. In this case, it is common to calculate the relative position between the magnet and the magnetic sensor by assuming that the magnetic flux density detectable by the magnetic sensor changes linearly with the relative movement between the magnetic sensor and the magnet.

[0006] Patent Document 2 discloses an image blur correction device having a configuration in which the driving magnet in the voice coil motor type driving device described above is also used as a magnet for position detection. Patent Document 3 also discloses a position detection device in which a position detection stroke is ensured by providing a notch in the magnet or by dividing the magnet into two parts. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6172993 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-219338 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-246134 Summary of the Invention [Problem to be solved by the invention]

[0008] However, with the technology disclosed in Patent Document 1, if the drive amount (the amount of movement of the movable part) is increased and thrust is ensured at a position where the relative movement amount between the coil and the magnet is large, the size of the drive device in the drive direction (the direction of movement of the movable part) inevitably increases. Also, when the drive amount increases, it is necessary to prevent the movable part from colliding with other parts (components) at the destination of its movement, which inevitably pushes the drive device outward, resulting in an increase in the size of the image stabilization device.

[0009] The drive device disclosed in Patent Document 2 detects the position of the moving part by detecting the magnetism of the magnet used for drive, thereby miniaturizing the image stabilization device. However, the range in which the magnetic flux density changes linearly is narrow within the range in which the magnetic sensor can detect the position of the moving part. Therefore, if the range in which the magnetic flux density changes linearly is the only range in which the position of the moving part can be detected, the technology disclosed in Patent Document 2 is not suitable for drive devices with large drive amounts.

[0010] The methods disclosed in Patent Document 1 or Patent Document 3 can be used to detect the drive amount or position of the movable part when the drive amount of the movable part is large. However, the technology disclosed in Patent Document 1 requires a magnet used for position detection in addition to the magnet used for driving the movable part, which increases the number of parts, driving up costs and making it difficult to save space. On the other hand, the technology disclosed in Patent Document 3 requires a small magnet volume, making it difficult to ensure thrust.

[0011] An object of the present invention is to provide a small driving device that is capable of moving over a large stroke while ensuring the necessary thrust. [Means for solving the problem]

[0012] The driving device of the present invention comprises a fixed part, a movable part holding an optical element, a coil arranged on one side of the fixed part and the movable part, and a first magnet part and a second magnet part arranged on the other side of the fixed part and the movable part so as to sandwich the coil with a predetermined gap in the optical axis direction of the optical element, and is a driving device that moves the movable part in a first direction perpendicular to the optical axis direction, and is characterized in that when viewed from the optical axis direction, in the first direction, the distance from the optical axis of the optical element to the polarization line of the first magnet part is different from the distance from the optical axis to the polarization line of the second magnet part. [Effects of the Invention]

[0013] According to the present invention, it is possible to realize a small-sized driving device that is capable of movement over a large stroke while ensuring the necessary thrust. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an imaging device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of an image blur correction unit according to the first embodiment, which is provided in the imaging device. [Figure 3] 3A and 3B are a front view and a cross-sectional view illustrating the configuration of the image blur correction device of FIG. 2. [Figure 4] FIG. 3(b) is an enlarged view of part B in FIG. [Figure 5] FIG. 2 is a diagram for explaining the definition of polarization lines in the upper magnet group and the lower magnet group. [Figure 6] 5 is a diagram simply illustrating a state in which the movable part has moved downward from the state in FIG. 4, similar to FIG. 4. FIG. [Figure 7] 10 is a diagram showing a comparison of the relationship between magnet position and magnetic flux density in the image stabilization device between the upper magnet group of this embodiment and a conventional magnet. FIG. [Figure 8] FIG. 10 is a cross-sectional view showing a schematic configuration of an image blur correction device according to a second embodiment. [Figure 9] 9 is a diagram simply illustrating, similar to FIG. 8, a state in which the movable part has moved downward from the state in FIG. 8. FIG. [Figure 10]FIG. 10 is a diagram showing the relationship between the magnet position and the magnetic flux density in a conventional image stabilization device. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Here, a configuration in which a driving device according to the present invention is embodied as an image stabilization device for an imaging device will be described.

[0016] Fig. 1(a) is a cross-sectional view showing a schematic configuration of an imaging device according to an embodiment of the present invention. Fig. 1(b) is a block diagram showing the electrical configuration of the imaging device. The imaging device is generally composed of an imaging device body 1 and an interchangeable lens 2 that is detachable from the imaging device body 1.

[0017] The imaging device body 1 includes a camera system control circuit 5, an image sensor 6, an image processing unit 7, a memory unit 8, a display unit 9, an operation detection unit 10, an image blur correction unit 14, a blur detection unit 15, and a shutter mechanism 16. The display unit 9 includes an in-finder display device 9a and a rear display panel 9b. The interchangeable lens 2 includes a lens group 3, a lens system control circuit 12, and a lens drive unit 13. When the interchangeable lens 2 is attached to the imaging device body 1, the camera system control circuit 5 and the lens system control circuit 12 are connected to each other via electrical contacts 11 so that they can communicate with each other.

[0018] The blur detection unit 15 is, for example, a gyro sensor. The blur detection unit 15 detects blur of the imaging device in a first direction and a second direction that are orthogonal to each other in a plane orthogonal to the imaging optical axis 4, and sends a signal indicating the amount of blur to the camera system control circuit 5. Based on the signal obtained from the blur detection unit 15, the camera system control circuit 5 calculates a target position of the imaging element 6 to reduce image blur in the subject image, calculates drive amounts in the first and second directions for moving the imaging element 6 to the target position, and sends the drive amounts to the image blur correction unit 14. The image blur correction unit 14 controls the energization of a coil 205 (described below) in accordance with the drive amount (control signal) received from the camera system control circuit 5, and translates the imaging element 6 in a plane approximately parallel to its imaging surface or rotates it around the imaging optical axis 4 to move the imaging element 6 to the target position. This makes it possible to reduce (correct) image blur caused by blur of the imaging device due to camera shake or the like. Among the components constituting the imaging device, those not directly related to image blur correction may be of known configuration, and therefore detailed description thereof will be omitted.

[0019] Fig. 2 is an exploded perspective view of the image blur correction unit 14 according to the first embodiment of the present invention. Fig. 3(a) is a front view (viewed from the optical axis direction) of the image blur correction unit 14. Fig. 3(b) is a cross-sectional view taken along the arrow AA in Fig. 3(a).

[0020] The image blur correction unit 14 includes an upper yoke 101, screws 102a, 102b, and 102c, an upper magnet group 103 (first magnet portion), spacers 105a, 105b, and 105c, a lower magnet group 107 (second magnet portion), a lower yoke 108, and a base plate 110. The image blur correction unit 14 also includes an FPC 201, a coil 205, a movable frame 206, and balls 301a, 301b, and 301c.

[0021] The upper magnet group 103 has a first upper magnet portion 103a, a second upper magnet portion 103c, and a third upper magnet portion 103e. The lower magnet group 107 has a first lower magnet portion 1071, a second lower magnet portion 1072, and a third lower magnet portion 1073. The first lower magnet portion 1071 has lower magnets 107a and 107b, the second lower magnet portion 1072 has lower magnets 107c and 107d, and the third lower magnet portion 1073 has lower magnets 107e and 107f.

[0022] The FPC 201 is a flexible printed wiring board on which position detection elements 202a, 202b, and 202c are mounted. In the following description, when there is no need to distinguish between the position detection elements 202a, 202b, and 202c, they will be referred to as "position detection elements 202." The coil 205 includes a first coil 205a, a second coil 205b, and a third coil 205c. Of these components that make up the image blur correction unit 14, components with numbers in the 100s make up fixed parts, and components with numbers in the 200s make up movable parts that are movable relative to the fixed parts.

[0023] FIG. 4 is an enlarged view of portion B shown in FIG. 3(b). Note that FIG. 4 is simplified by omitting the illustration of components other than the magnetic circuit, which will be described later. The upper yoke 101, the third upper magnet portion 103e, the third lower magnet portion 1073, and the lower yoke 108 form a third magnetic circuit, which is a so-called closed magnetic circuit. Similarly, although not shown, the upper yoke 101, the first upper magnet portion 103a, the first lower magnet portion 1071, and the lower yoke 108 form a first magnetic circuit. Furthermore, the upper yoke 101, the second upper magnet portion 103c, the second lower magnet portion 1072, and the lower yoke 108 form a second magnetic circuit.

[0024] Lower magnets 107a, 107b, 107c, 107d, 107e, and 107f are attracted to and adhesively fixed to lower yoke 108 by magnetic force. The magnets constituting lower magnet group 107 are fixed so that the magnetization directions of adjacent magnets in a pair are opposite to each other in the optical axis direction. For example, as shown in FIG. 4, in third lower magnet section 1073, lower magnets 107e and 107f are arranged so that the north and south poles of each magnet are opposite to each other in the optical axis direction. First lower magnet section 1071 and second lower magnet section 1072 also have the same configuration as third lower magnet section 1073 in terms of the orientation of their magnetic poles.

[0025] The first upper magnet portion 103a, the second upper magnet portion 103c, and the third upper magnet portion 103e are each attracted to the upper yoke 101 by magnetic force and are also adhesively fixed thereto.

[0026] The first upper magnet portion 103a is disposed in a position facing the first lower magnet portion 1071, and is two-pole magnetized on both sides so that it has the same magnetization direction as the first lower magnet portion 1071. Similarly, the second upper magnet portion 103c is disposed in a position facing the second lower magnet portion 1072, and is two-pole magnetized on both sides so that it has the same magnetization direction as the second lower magnet portion 1072. Furthermore, the third upper magnet portion 103e is disposed in a position facing the third lower magnet portion 1073, and is two-pole magnetized on both sides so that it has the same magnetization direction as the third lower magnet portion 1073.

[0027] As shown in Fig. 4, an arc-shaped groove 103j is provided in the approximate center of the surface of the third upper magnet portion 103e facing the third lower magnet portion 1073, along the longitudinal direction of the third upper magnet portion 103e (the "second direction" shown in Fig. 4). Similarly, an arc-shaped recess is provided in the approximate center of the surface of the second upper magnet portion 103c facing the second lower magnet portion 1072, along the longitudinal direction of the second upper magnet portion 103c (the "first direction" shown in Fig. 4). Furthermore, an arc-shaped recess is provided in the approximate center of the surface of the first upper magnet portion 103a facing the first lower magnet portion 1071, along the longitudinal direction (the first direction) of the first upper magnet portion 103a.

[0028] Although details will be described later, by configuring the first upper magnet portion 103a and the first lower magnet portion 1071 as described above, a large magnetic flux density can be generated in the optical axis direction between the first upper magnet portion 103a and the first lower magnet portion 1071. Similarly, a large magnetic flux density can be generated in the optical axis direction between the second upper magnet portion 103c and the second lower magnet portion 1072, and between the third upper magnet portion 103e and the third lower magnet portion 1073.

[0029] In this way, a strong attraction force is generated between the upper yoke 101 and the lower yoke 108, but the upper yoke 101 and the lower yoke 108 are maintained at a predetermined distance in the optical axis direction by spacers 105a, 105b, and 105c disposed between them. The distance between the upper yoke 101 and the lower yoke 108 is set so that the movable frame 206 and the FPC 201 can be disposed between the upper magnet group 103 and the lower magnet group 107, while also ensuring a certain gap.

[0030] The spacers 105a, 105b, and 105c are fixed to the upper yoke 101 by screws 102a, 102b, and 102c. The spacers 105a, 105b, and 105c have rubber on their bodies, which form mechanical ends (so-called stoppers) of the movable frame 206. In other words, the movable frame 206 is configured to not protrude more than necessary outside the image blur correction unit 14 within a plane perpendicular to the imaging optical axis 4.

[0031] The movable frame 206 is made of, for example, a magnesium alloy or an aluminum alloy, and is lightweight and highly rigid. A first coil 205a, a second coil 205b, a third coil 205c, and an FPC 201 are fixed to the movable frame 206 to form a movable section 200. The movable section 200 is movably held on the base plate 110 via three balls 301a, 301b, and 301c, which roll. The imaging element 6 is directly or indirectly attached to the movable frame 206 and moves integrally with the movable frame 206.

[0032] The FPC 201 is arranged on the upper magnet group 103 side of the movable frame 206. The FPC 201 serves to electrically connect the camera system control circuit 5 to the image sensor 6 and the image blur correction unit 14. Therefore, a connector for electrically connecting the image sensor 6, the coil 205, and the position detection element 202 is mounted on the FPC 201.

[0033] Position detection elements 202a, 202b, and 202c are mounted on the FPC 201 so as to be nested inside (in the inner holes of) the windings of the first coil 205a, second coil 205b, and third coil 205c, respectively. For example, a Hall element or the like is used for the position detection element 202, and the position of the movable part 200 relative to the fixed part is detected using the first magnetic circuit, second magnetic circuit, and third magnetic circuit. Note that a magnetoresistance element may also be used for the position detection element 202.

[0034] The magnetic flux detection position of position detector 202 is closer to upper magnet group 103 than to lower magnet group 107. In other words, the distance between position detector 202 and upper magnet group 103 is shorter than the distance between position detector 202 and lower magnet group 107, and the reason for this configuration will be described later.

[0035] In the image blur correction unit 14, when a current flows through the coil 205, a force is generated according to Fleming's left-hand rule, which allows the movable part 200 to move relative to the fixed part. Three drive units are formed by inserting one coil into each of the first magnetic circuit, the second magnetic circuit, and the third magnetic circuit, and each drive unit can be driven independently. When driving the movable part 200, feedback control is generally performed based on the output signal (Hall element signal) of the position detection element 202. This allows the movable part 200 to be translated in a plane perpendicular to the imaging optical axis 4 and rotated around the imaging optical axis 4 with high precision. Note that, to rotate the movable part 200 around the imaging optical axis 4, it is sufficient to control the output signal values ​​of the position detection elements 202a and 202b so that they have opposite phases. Known control methods can be used to control the drive of the image blur correction unit 14, so a detailed description will be omitted.

[0036] Next, we will explain the external shapes of the magnets that make up upper magnet group 103 and lower magnet group 107. The drive unit shown in Fig. 4 is configured by inserting third coil 205c between third upper magnet section 103e and third lower magnet section 1073 (lower magnets 107e, 107f) that form a third magnetic circuit, and when current is applied to third coil 205c, movable section 200 is driven in a first direction.

[0037] The third upper magnet portion 103e must be placed in a location where it will not collide (contact) with the imaging element 6 when it moves the required amount of movement, and is placed at a position where the shortest distance from the imaging optical axis 4 is '103L'. On the other hand, the third lower magnet portion 1073 is placed at a position where the shortest distance from the imaging optical axis 4 is '107L'. Here, unlike the third upper magnet portion 103e, the third lower magnet portion 1073 does not overlap with the imaging element 6 in its position along the optical axis. In other words, the third lower magnet portion 1073 does not interfere with the imaging element 6 regardless of the amount of movement of the imaging element 6, so 103L > 107L can be satisfied.

[0038] On the other hand, miniaturization is required for the image blur correction unit 14. Therefore, as distances related to the outermost size of the image blur correction unit 14, if the outermost distances from the photographing optical axis 4 to the third upper magnet part 103e and the third lower magnet part 1073 are respectively set to '103K' and '107K', these are approximately equal.

[0039] As can be seen from these, in this embodiment, the length in the first direction of the third lower magnet portion 1073 is longer than the length in the first direction of the third upper magnet portion 103e. Furthermore, the first direction length '107h' of the lower magnet 107e and the first direction length '107i' of the lower magnet 107f constituting the third lower magnet portion 1073 have the relationship 107h<107i.

[0040] FIG. 5 is a diagram illustrating the definition of polarization lines in the upper magnet group 103 and the lower magnet group 107, using the third lower magnet section 1073 as an example. The curve Bc in FIG. 5 represents a magnetic flux density curve showing the change in magnetic flux density with respect to the position of the lower magnets 107e and 107f. The magnetic flux density is divided into the north pole side and the south pole side at the zero (0) position. The polarization line 107N of the third lower magnet section 1073 is a line that passes through the boundary between the north pole and the south pole on the curve Bc. In other words, the polarization line 107N of the third lower magnet section 1073 is located at an imaginary position within the lower magnet 107f, not at the contact position of the outer contours of the lower magnets 107e and 107f. Furthermore, the polarization line 107N passes near the center of gravity of the third lower magnet section 1073.

[0041] The polarization line 103N of the third upper magnet section 103e is located approximately at the center of the third upper magnet section 103e in the first direction as shown in Fig. 4, in accordance with the definition in Fig. 5. In other words, the polarization line 103N of the third upper magnet section 103e passes near the center of gravity of the third upper magnet section 103e. Therefore, the polarization line 103N of the third upper magnet section 103e and the polarization line 107N of the third lower magnet section 1073 do not coincide when viewed from the optical axis direction but are offset in the first direction. The reason for this configuration will be explained below.

[0042] Fig. 6 is a diagram simply illustrating, similar to Fig. 4, a state in which the movable part 200 has moved downward (the first direction is downward) from the state in Fig. 4. When the movable part 200 moves downward, the relative position of the third coil 205c with respect to the first upper magnet part 103a and the third lower magnet part 1073 changes.

[0043] 10 shows a graph illustrating the relationship between magnet position and magnetic flux density in a conventional configuration in which the polarization lines of the upper magnet section and the lower magnet section are aligned when viewed from the optical axis direction. The curve Bf represents the magnetic flux density curve, and the linearly changing range Lf represents the range of magnetic flux typically used by a magnetic sensor to detect the position of a moving part.

[0044] In conventional magnet units, the polarization line is located at the center position (the magnet position on the horizontal axis is zero (0)), and the magnetic flux density is small between the center position and the end (the end in the first direction), resulting in a small thrust in the coil winding facing the area with low magnetic flux density. If the coil passes over the polarization line of the magnet, a force in the opposite direction to the direction of the desired drive is generated in the coil winding facing the area beyond. In other words, as the movement amount of the movable part 200 increases, the thrust decreases.

[0045] In contrast, the image blur correction unit 14 is configured so that the polarization line 103N of the third upper magnet unit 103e and the polarization line 107N of the third lower magnet unit 1073 do not coincide when viewed from the optical axis direction. Specifically, in a first direction when viewed from the optical axis direction, the distance from the imaging optical axis 4 to the polarization line 103N is greater than the distance from the imaging optical axis 4 to the polarization line 107N.

[0046] 6, even when the third coil 205c protrudes from the end of the third upper magnet portion 103e, the third coil 205c is positioned opposite the third lower magnet portion 1073. In particular, the third coil 205c faces the lower magnet 107f of the third lower magnet portion 1073 in an area with high magnetic flux density. This makes it possible for the image blur correction unit 14 to maintain a large thrust even when the movable portion 200 is moved.

[0047] As mentioned above, an arc-shaped groove 103j is provided in the center of the third upper magnet portion 103e along the second direction (a direction perpendicular to the first direction and the optical axis direction), and the reason for this will be explained in detail below.

[0048] FIG. 7 is a graph illustrating how the magnetic flux density detected by the position detection element 202c changes with magnet position. The curve Bc in FIG. 7 shows the change in magnetic flux density with the position of the third upper magnet portion 103e. Meanwhile, the curve Bf is the same as the curve Bf in FIG. 10 and shows the change in magnetic flux density with the position of the magnet 903, which does not have the groove 103j, according to the conventional example. The roughly linear range Lc in the curve Bc corresponds to the stroke within which position detection is possible in the image blur correction unit 14 according to this embodiment, which uses the third upper magnet portion 103e. The roughly linear range Lf in the curve Bf corresponds to the stroke within which position detection is possible in the conventional image blur correction device, which uses the magnet 903. Comparing the range Lc and the range Lf, it can be seen that the range Lc is wider than the range Lf. In other words, the image blur correction unit 14 is configured to be able to detect the position of the movable portion 200 even when the movable portion 200 is moved significantly.

[0049] In this way, by providing groove 103j in the magnet, the position detection range of movable part 200 can be widened, but groove 103j is provided in upper magnet group 103, not on the side of lower magnet group 107. The reason for this is that lower magnet group 107, which has a longer length in the first direction than upper magnet group 103, plays a role in increasing the magnetic field and ensuring thrust by maximizing the size of the magnets. Groove 103j is provided in upper magnet group 103 so that the role of widening the position detection range can be played by upper magnet group 103, which has a shorter length in the first direction than lower magnet group 107.

[0050] Incidentally, in the image blur correction unit 14, the position detecting element 202 is disposed in a position closer to the upper magnet group 103 than to the lower magnet group 107 (see FIG. 4). This makes it possible for the position detecting element 202 to detect magnetic flux with characteristics such as the curve Bc shown in FIG. 7. If the position detecting element 202 were disposed in a position closer to the lower magnet group 107, it would detect magnetic flux with characteristics such as the curve Bf in FIG. 7, which would narrow the linear range and make it unsuitable for detecting large strokes.

[0051] As explained above, in the image blur correction unit 14 according to the first embodiment, it is possible to widen the position detection range of the movable unit 200, in other words, to increase the stroke for driving the movable unit 200. In this case, it is possible to achieve a reduction in the size of the image blur correction unit 14 while maintaining a sufficiently large thrust.

[0052] The characteristic configuration of the image blur correction unit 14 has been described in detail using the example of the drive unit consisting of the third upper magnet unit 103e, the third lower magnet unit 1073, and the third coil 205c, but the same applies to the remaining two drive units (magnetic circuits). That is, in a drive unit in which the first coil 205a is inserted into the magnetic field generated between the first upper magnet unit 103a and the second lower magnet unit 1072 (lower magnets 107a and 107b), a thrust in the second direction is generated by energizing the first coil 205a. Similarly, in a drive unit in which the second coil 205b is inserted into the magnetic field generated between the second upper magnet unit 103c and the second lower magnet unit 1072 (lower magnets 107c and 107d), a thrust in the second direction is generated by energizing the second coil 205b. The relationship between the length of the magnets and the notches in these drive units is similar to the relationship between the length of the magnets and the notches in the drive unit composed of the third upper magnet unit 103e, the third lower magnet unit 1073 and the third coil 205c, so explanations will be omitted.

[0053] Next, an image blur correction unit according to a second embodiment of the present invention will be described. The image blur correction unit according to the second embodiment differs from the image blur correction unit 14 according to the first embodiment only in the configurations of the upper magnet group and the lower magnet group, and the following description will focus on these differences, omitting a description of the configuration common to the image blur correction unit 14.

[0054] Fig. 8 is a cross-sectional view showing the configuration of the third upper magnet portion 4033 and the third lower magnet portion 4073 in the image blur correction unit 14A according to the second embodiment, similar to Fig. 4. The image blur correction unit 14A has three drive units (magnetic circuits), and Fig. 8 shows a representative drive unit made up of the third upper magnet portion 4033, the third lower magnet portion 4073, and the third coil 205c. In Fig. 8, the same components as those constituting the image blur correction unit 14 according to the first embodiment are denoted by the same reference numerals.

[0055] The third upper magnet section 4033 is composed of upper magnets 403e and 403f, and the third lower magnet section 4073 is composed of lower magnets 407e and 407f. By passing current through the third coil 205c, which is disposed in the magnetic field formed by the third upper magnet section 4033 and the third lower magnet section 4073, a thrust force is generated that moves the movable section 200 in the first direction.

[0056] The same magnet is used for the upper magnet 403e and the upper magnet 403f, and the upper magnet 403e and the upper magnet 403f are arranged on the upper yoke 101 so that their magnetization directions are opposite to each other in the first direction. Therefore, the upper magnet 403e and the upper magnet 403f have the same length in the first direction. Furthermore, the upper magnet 403e and the upper magnet 403f are held on the upper yoke 101 with a certain distance (gap) between them in the first direction. Because the upper magnet 403e and the upper magnet 403f have the same length in the first direction, the polarization line 403N of the third upper magnet part 4033 is located approximately in the center between the upper magnet 403e and the upper magnet 403f. The upper magnet 403f needs to be arranged in a location where it will not collide (contact) with the image sensor 6 when it moves the required amount, and is arranged at a distance '403L' from the imaging optical axis 4.

[0057] On the other hand, the lower magnet 407f constituting the third lower magnet part 4073 is positioned at a distance '407L' from the photographing optical axis 4. Unlike the third upper magnet part 4033, the third lower magnet part 4073 does not overlap with the image sensor 6 in the position along the optical axis, and therefore does not interfere with the image sensor 6 regardless of the amount of movement of the image sensor 6, and so 403L > 407L.

[0058] Miniaturization is also required for image blur correction unit 14A. Therefore, as with image blur correction unit 14, in image blur correction unit 14A, if the outermost distances from the imaging optical axis 4 to upper magnet 403e and lower magnet 407e are '403K' and '407K', respectively, these are approximately equal, i.e., 403K ≈ 407K. Furthermore, the same magnet is used for lower magnet 407e and lower magnet 407f, and therefore, length '407h' of lower magnet 407e in the first direction is the same as length '407i' of lower magnet 407f in the first direction.

[0059] Lower magnet 407e and lower magnet 407f are arranged on lower yoke 108 so that their magnetization directions are opposite to each other in the first direction and so that they are in contact with each other in the first direction. Therefore, polarization line 407N of third lower magnet portion 4073 is located at a position approximately equal to the contact surface between lower magnet 407e and lower magnet 407f. As a result, polarization line 403N of third upper magnet portion 4033 and polarization line 407N of third lower magnet portion 4073 do not coincide when viewed from the optical axis direction but are offset in the first direction.

[0060] The reason why polarization line 403N and polarization line 407N do not coincide when viewed from the optical axis direction will be described with reference to FIG. 9. FIG. 9 is a diagram, similar to FIG. 8, that simply shows a state in which movable part 200 has moved downward from the state in FIG. 8. As in the state in FIG. 9, even when the entire area of ​​third coil 205c is no longer facing third upper magnet part 4033, almost the entire area faces third lower magnet part 4073 in a range where magnetic flux density is high. This allows image blur correction unit 14A to maintain a high thrust.

[0061] Now, the reason why upper magnets 403e and 403f are arranged with a certain gap in the first direction is that, similar to the first embodiment, it is possible to widen the range in which the position of movable part 200 can be detected. In other words, it is possible to widen the stroke over which the movement of movable part 200 can be controlled, but since this configuration is well known, a detailed description thereof will be omitted.

[0062] Compared to the image blur correction unit 14 according to the first embodiment, the image blur correction unit 14A has a smaller total volume of magnets in the upper magnet unit and a narrower range in which the magnetic flux density changes linearly. However, the upper magnets 403e and 403f have a simple shape and do not require the groove 103j of the third upper magnet unit 103e. This makes the image blur correction unit 14A effective for applications requiring a short detection stroke. Furthermore, the reduction in thrust force due to the reduction in magnet volume in the third upper magnet unit 4033 can be compensated for by increasing the volume of the third lower magnet unit 4073, thereby ensuring the necessary driving force. As with the image blur correction unit 14, the third upper magnet unit 4033 also serves to expand the position detection range in the image blur correction unit 14A. Therefore, the position detection element 202c is positioned closer to the third upper magnet unit 4033 than the third lower magnet unit 4073.

[0063] While the present invention has been described in detail above based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the present invention are also included in the present invention. Furthermore, each of the above-described embodiments merely represents one embodiment of the present invention, and each embodiment can be combined as appropriate.

[0064] For example, the configuration of the upper magnet section in the first embodiment may be combined with the configuration of the lower magnet section in the second embodiment, or conversely, the configuration of the upper magnet section in the second embodiment may be combined with the configuration of the lower magnet section in the first embodiment. Furthermore, in the image blur correction unit 14, a groove is provided in the upper magnet section constituting the upper magnet group, and a magnet with an N pole and an S pole integrally magnetized on both sides is used, but a similar structure may be realized by bringing two magnets with notched edges into contact. Furthermore, although the image blur correction unit composed of three drive units with equivalent configurations has been described, all three drive units do not need to be the same.

[0065] The drive device according to the present invention is realized by disposing a coil on one of the movable part and the fixed part, and a magnet on the other. In the above embodiment, the coil was disposed on the movable part and the magnet was disposed on the fixed part in order to minimize the weight of the movable part, but the arrangement of the magnet and coil can also be reversed. Furthermore, in the above embodiment, an image blur correction unit of an imaging device was taken as an example of an application of the drive device according to the present invention, and an imaging element was used as a specific example of an optical member used for image blur correction. However, the drive device according to the present invention is not limited to this, and can be applied to an image blur correction unit that drives an image blur correction lens provided in an interchangeable lens within a plane approximately perpendicular to the imaging optical axis.

[0066] Furthermore, the driving device according to the present invention can be applied to any device other than an imaging device, as long as it moves a movable part within a plane. For example, an XY stage can be given as an example of an application of the driving device according to the present invention. Depending on the equipment to which the driving device according to the present invention is applied, the driving device may be configured to include one or any number of driving parts. [Explanation of symbols]

[0067] 1. Imaging device body 2 Interchangeable lenses 14,14A Image stabilization unit 15 Shake detection unit 103e Third upper magnet section 103j Groove 103N, 107N polarized wire 107e, 107f Lower magnet 201 FPC 202 Position detection element 1073 Third Lower Magnet Section 205 Coil

Claims

1. A fixed portion; a movable part that holds an optical member; a coil disposed in one of the fixed part and the movable part; a first magnet portion and a second magnet portion disposed on the other of the fixed portion and the movable portion so as to sandwich the coil with a predetermined gap therebetween in the optical axis direction of the optical member; a driving device that moves the movable part in a first direction perpendicular to the optical axis direction, A driving device characterized in that, in the first direction when viewed from the optical axis direction, the distance from the optical axis of the optical element to the polarization line of the first magnet portion is different from the distance from the optical axis to the polarization line of the second magnet portion.

2. A fixed portion; a movable part that holds an optical member; a coil disposed in one of the fixed part and the movable part; a first magnet portion and a second magnet portion disposed on the other of the fixed portion and the movable portion so as to sandwich the coil with a predetermined gap therebetween in the optical axis direction of the optical member; a driving device that moves the movable part in a first direction perpendicular to the optical axis direction, a length of the first magnet portion in the first direction is smaller than a length of the second magnet portion; A driving device characterized in that, in the first direction when viewed from the optical axis direction, the distance from the optical axis of the optical element to the center of gravity of the first magnet portion is greater than the distance from the optical axis to the center of gravity of the second magnet portion.

3. The driving device according to claim 2, characterized in that the second magnet portion is arranged in a position in the optical axis direction such that it does not come into contact with the optical element even when the optical element is moved in the first direction.

4. A driving device as described in any one of claims 1 to 3, characterized in that a groove is formed in the surface of the first magnet portion facing the coil, at the center in the first direction, along the optical axis direction and a direction perpendicular to the first direction.

5. the first magnet portion has two magnets having the same length in the first direction, 4. The drive device according to claim 1, wherein the two magnets are arranged with a predetermined gap therebetween in the first direction.

6. a detection means for detecting the position of the movable part; 6. The driving device according to claim 1, wherein the detecting means is disposed at a position closer to the first magnet portion than to the second magnet portion in the optical axis direction.

7. the movable portion includes a flexible printed circuit board that holds the coil, 7. The driving device according to claim 6, wherein the detecting means is mounted on the flexible printed wiring board in an inner hole of the coil.

8. A drive device having a fixed part and a movable part, the drive device moving the fixed part and the movable part relative to each other in a first direction, a coil disposed in one of the fixed part and the movable part; a first magnet portion and a second magnet portion disposed on the other of the fixed portion and the movable portion with a predetermined gap therebetween in a second direction perpendicular to the first direction, A driving device characterized in that, when viewed from the second direction, the position of the polarization line of the first magnet portion and the position of the polarization line of the second magnet portion do not overlap.

9. A drive device according to any one of claims 1 to 8; an imaging element held by the movable part, The image stabilization device is characterized in that the movable portion is movable within a plane substantially parallel to an image forming surface of the image sensor.

10. A drive device according to any one of claims 1 to 8; an image blur correction lens held by the movable section, The image stabilization device according to claim 1, wherein the movable portion is movable within a plane substantially perpendicular to the optical axis of the image stabilization lens.

11. An imaging device comprising the image blur correction device according to claim 9 or 10.

Images