JP7679223B2 - Drive device, imaging device, and lens barrel - Google Patents

Description

The present invention relates to a drive device, an imaging device, and a lens barrel, and in particular to an imaging device and a lens barrel equipped with a drive device that uses a voice coil motor.

Conventionally, there are known driving devices that move a movable part in a plane relative to a fixed part, and a configuration called a voice coil motor (VCM) system is known as a configuration for generating a driving force to drive the movable part.

In the VCM method, a magnet is placed on one of the movable and fixed parts, and a coil is placed on the other, and a driving force is generated by passing electricity through the coil in the magnetic circuit formed by the magnets. An example of the application of such a driving device is a blur correction mechanism mounted on an imaging device. In a blur correction mechanism, an imaging element or a blur correction lens is mounted on the movable part, and the movable part is driven to cancel out the blur based on the amount of blur detected by a specified sensor.

In a blur correction mechanism that uses the VCM method, multiple balls are usually placed between the movable and fixed parts so that they can roll, thereby reducing contact resistance and enabling smooth operation. In this case, a method is used in which the fixed and movable parts are attracted to each other using a spring or magnet to ensure that the balls are in contact with the movable and fixed parts and are sandwiched between them (see Patent Documents 1 and 2).

Patent No. 6511495 Patent No. 6719056

For example, when taking pictures while walking using an imaging device, the amount of shaking increases, and there is a demand for a shake correction device that can offset such a large amount of shaking. A shake correction device for an imaging device can correct a larger amount of shaking by increasing the amount of movement of the movable part relative to the fixed part.

To address this issue, the technologies described in Patent Documents 1 and 2 use magnets and magnetic bodies as a means for attracting the movable and fixed parts to each other, but are configured in such a way that as the amount of movement (movement distance) increases, a return force to the center is generated by the magnetic force. While this return force can quickly return the camera to a state where shake correction is not being performed, it also increases the drive load when shake correction is performed.

The present invention aims to provide a drive device that reduces the return force to the center when the movable part is moved relative to the fixed part, thereby reducing the load on the actuator that drives the movable part.

The driving device of the present invention comprises a fixed part, a movable part arranged to be movable relative to the fixed part within a predetermined range in a plane, a plurality of rolling members arranged between the fixed part and the movable part, an actuator for driving the movable part, and a biasing means for biasing the movable part against the fixed part via the rolling members, wherein the biasing means includes a magnet and a magnetic body, one of the magnet and the magnetic body being held by the movable part and the other being held by the fixed part, and when the actuator is driven to move the movable part, the range within which the magnet can move relative to the magnetic body does not extend beyond the end of the magnetic body when viewed from a direction perpendicular to the plane, and when the magnet extends beyond the end of the magnetic body when viewed from a direction perpendicular to the plane, the biasing force of the biasing means in a direction parallel to the plane is greater than when the magnet does not extend beyond the end of the magnetic body .

The present invention provides a drive device that reduces the return force to the center when the movable part is moved relative to the fixed part, thereby reducing the load on the actuator that drives the movable part.

1 is a diagram illustrating a schematic configuration of an imaging device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a first image stabilization unit included in the imaging device. FIG. 13 is another exploded perspective view of the first image stabilization unit included in the imaging device; FIG. 2 is an exploded perspective view of a movable portion that constitutes the first image blur correction unit. FIG. 11 is another exploded perspective view of the movable portion that constitutes the first image blur correction unit. 3A and 3B are a first projection view and a first cross-sectional view in the optical axis direction of a biasing portion constituted by a rear yoke and a thrust magnet; 5A and 5B are a second projection view and a second cross-sectional view in the optical axis direction of a biasing portion constituted by a rear yoke and a thrust magnet. 3A and 3B are a projection view and a cross-sectional view in the optical axis direction of the actuator. 4 is a projection view of a first image stabilization unit in the optical axis direction when the main body of the imaging device is not powered on; FIG. 3A and 3B are a front view and a cross-sectional view of a movable part that constitutes the first image blur correction unit. 3A and 3B are a front view and a cross-sectional view of a first image stabilization unit. FIG. 11B is a partially enlarged view of the cross-sectional view of FIG. FIG. 4 is a diagram showing temperature-strength characteristics of a first adhesive joint and a second adhesive joint.

Embodiments of the present invention will be described in detail below with reference to the attached drawings. Here, an example will be described in which a drive device according to the present invention is applied to an image stabilization device for an imaging device, but application examples of the drive device according to the present invention are not limited to imaging devices.

Figure 1 is a diagram illustrating the schematic configuration of an imaging device 10 according to an embodiment of the present invention. The imaging device 10 is a so-called mirrorless digital camera, and has an imaging device body 10a (hereinafter referred to as "body unit 10a") and a lens barrel 10b that is detachable from the body unit 10a.

The main body 10a includes an imaging element 11 having an imaging surface 11a, a base member 13, a main body side mount member 13a, a camera control unit 14, a first blur correction control unit 15a, a first vibration detection unit 16a, an image processing unit 17, and a first blur correction unit 20. The lens barrel 10b includes an imaging optical system 12 including a blur correction lens 12b, a lens side mount member 13b, a second blur correction control unit 15b, a second vibration detection unit 16b, and a second blur correction unit 60.

The virtual light ray that is representative of the light beam irradiated to the imaging surface 11a of the imaging element 11 through the imaging optical system 12 is called the "imaging optical axis 12a" (hereinafter referred to as the "optical axis 12a"), and the plane perpendicular to the optical axis 12a is called the "optical axis perpendicular plane" (hereinafter referred to as the "optical axis perpendicular plane 12c"). The optical axis 12a passes through the center of the imaging surface 11a and is perpendicular to the imaging surface 11a. In addition, in order to clarify the arrangement and positional relationship of each part constituting the imaging device 10 within the imaging device 10, as shown in FIG. 1, the X direction, Y direction, and Z direction that are perpendicular to each other are defined. The Z direction is parallel to the optical axis 12a, the X direction is the width direction of the imaging device 10, and the Y direction is the height direction of the imaging device 10. When the X direction and the Z direction are both in a horizontal plane, the Y direction is the vertical direction. Therefore, the optical axis perpendicular plane 12c is the XY plane.

The imaging element 11 is composed of photoelectric conversion elements such as a CMOS image sensor or a CCD image sensor, and is arranged so that the imaging surface 11a faces the subject side (lens barrel 10b side) and is perpendicular to the optical axis 12a. The imaging element 11 generates an image signal by photoelectrically converting the optical image of the subject formed on the imaging surface 11a by the imaging optical system 12. The image signal generated by the imaging element 11 is converted into image data through various processes in the image processing unit 17 and stored in a memory (storage device) (not shown). The camera control unit 14 is a calculation means in a main IC (not shown), and accepts input operations from the user via an operation means (not shown) to control the overall operation of the imaging device 10.

The imaging optical system 12 is composed of a group of lenses (not shown) arranged inside the lens barrel 10b, and forms an image of reflected light from a subject (not shown) on the imaging surface 11a of the imaging element 11. In the imaging device 10, in order to position the imaging element 11 with high positional accuracy relative to the optical axis 12a, the imaging element 11 is attached to a base member 13c provided on the main body 10a, and the lens barrel 10b is also connected to the base member 13c. At that time, the imaging element 11 is attached to the base member 13c via the first shake correction unit 20. In addition, the lens barrel 10b is connected to the base member 13c via the lens side mount member 13b and the main body side mount member 13a.

The first blur correction unit 20 corrects image blur caused by vibrations in the imaging device 10 by moving the imaging element 11 in a direction perpendicular to the optical axis or rotating it in the plane perpendicular to the optical axis 12c, thereby making it possible to obtain a clear image of the subject. Specifically, when the posture of the imaging device 10 changes with respect to the subject during imaging, the imaging position of the subject light beam on the imaging surface 11a of the imaging element 11 changes, causing blur in the image obtained through the imaging element 11. In this case, if the change in posture of the imaging device 10 is sufficiently small, the change in the imaging position is uniform within the imaging surface 11a and can be considered as translation or rotation movement (image surface blur) within the plane perpendicular to the optical axis 12c. Therefore, by translating or rotating the imaging element 11 within the plane perpendicular to the optical axis 12c so as to cancel out this image surface blur, a clear image of the subject with image blur corrected can be obtained. Note that the imaging element 11 may be configured to move in a direction perpendicular to the imaging surface when moving in a direction parallel to the imaging surface.

Similarly, the second blur correction unit 60 corrects image blur caused by vibrations in the imaging device 10 by moving the blur correction lens 12b in a direction perpendicular to the optical axis or rotating it within the plane perpendicular to the optical axis 12c, thereby making it possible to obtain a clear image of the subject. In other words, the optical axis 12a is refracted by moving the blur correction lens 12b in a direction perpendicular to the optical axis. At this time, the blur correction lens 12b is moved in a direction perpendicular to the optical axis so that the image plane blur is canceled. This makes it possible to obtain a clear image of the subject with image blur corrected. Note that the principle of blur correction by moving the imaging element 11 and the blur correction lens 12b is well known, so a detailed explanation will be omitted. In addition, the blur correction lens 12b may be configured to move in the optical axis direction when moving in the direction perpendicular to the optical axis.

The first blur correction unit 20 generally has a fixed part, a movable part, and multiple drive force generating parts. The fixed part is fixed to the base member 13c, and the movable part holds the image sensor 11. The movable part is supported by the fixed part with three degrees of freedom, and can move relative to the fixed part in a direction perpendicular to the optical axis and rotate within the plane perpendicular to the optical axis 12c. In other words, the first blur correction unit 20 is configured as a drive device (a so-called XYθ stage) capable of drive control on three axes, and is capable of moving the image sensor 11 in a direction perpendicular to the optical axis and rotating within the plane perpendicular to the optical axis 12c.

The second blur correction unit 60 generally has a fixed part, a movable part, and multiple drive force generating parts. The fixed part is fixed to a housing (not shown) of the lens barrel 10b, and the movable part holds the blur correction lens 12b. The movable part is supported by the fixed part with two degrees of freedom, and can move relative to the fixed part in a direction perpendicular to the optical axis. In other words, the second blur correction unit 60 is configured as a drive device (a so-called XY stage) capable of drive control on two axes, and is capable of moving the blur correction lens 12b in a direction perpendicular to the optical axis.

The first vibration detection unit 16a and the second vibration detection unit 16b are each composed of a gyro sensor, an acceleration sensor, etc., and are shake detection means that detect the angular velocity and acceleration in each direction of the imaging device 10 as shake information of the imaging device 10. The first shake correction control unit 15a and the second shake correction control unit 15b integrate the angular velocity and acceleration detected by the first vibration detection unit 16a and the second vibration detection unit 16b, respectively, to calculate the angle change amount and movement amount in each direction of the imaging device 10 as shake information. Furthermore, the first shake correction control unit 15a calculates a movement target value of the imaging element 11 based on the shake information detected by the first vibration detection unit 16a, and controls the drive of the first shake correction unit 20 to control the movement of the imaging element 11. Similarly, the second blur correction control unit 15b calculates a movement target value for the blur correction lens 12b based on the blur information detected by the second vibration detection unit 16b, and controls the drive of the second blur correction unit 60 to control the movement of the blur correction lens 12b.

The imaging device 10 may be configured to include only one of the first blur correction unit 20 and the second blur correction unit 60. If the first blur correction unit 20 is not included, the imaging element 11 is fixedly positioned relative to the optical axis 12a. If the second blur correction unit 60 is not included, the blur correction lens 12b is basically unnecessary. In other words, the imaging optical system 12 of the lens barrel 10b is designed to obtain the desired optical characteristics with a lens configuration that does not include the blur correction lens 12b.

Next, we will explain the detailed configuration of the first shake correction unit 20. Note that the configuration of the second shake correction unit 60 is similar to the configuration of the first shake correction unit 20, so the explanation will be omitted.

Figures 2 and 3 are exploded perspective views of the first blur correction unit 20, and the direction in which the first blur correction unit 20 is viewed is different between Figures 2 and 3. The first blur correction unit 20 has a fixed part 20a and a movable part 20b. Note that in Figures 2 and 3, the movable part 20b is shown not exploded, and the fixed part 20a is shown exploded.

The fixed portion 20a has a fixed member 21, a rear yoke 22, a first rear magnet group 23a, a second rear magnet group 23b, and a third rear magnet group 23c. The fixed member 21 is provided with a first opening 21a, a second opening 21b, and a third opening 21c. The first rear magnet group 23a, the second rear magnet group 23b, and the third rear magnet group 23c are each fixed to the rear yoke 22 with an adhesive or the like, and are arranged so as to be surrounded by the first opening 21a, the second opening 21b, and the third opening 21c.

In this embodiment, the first rear magnet group 23a, the second rear magnet group 23b, and the third rear magnet group 23c are configured with two magnets magnetized in the optical axis direction (Z direction) arranged to generate magnetic fields in opposite directions. However, this is not limited to this, and a single magnet magnetized with two poles may also be used.

The fixed part 20a also has a first pillar member 24a, a second pillar member 24b, a third pillar member 24c, a front yoke 25, a first front magnet 26a, a second front magnet 26b, and a third front magnet 26c. The front yoke 25 is fixed to the fixed member 21 with screws via the first pillar member 24a, the second pillar member 24b, and the third pillar member 24c. The first front magnet 26a, the second front magnet 26b, and the third front magnet 26c are each fixed to the front yoke 25 with an adhesive or the like.

In this embodiment, a single magnet magnetized with two poles is used as the first front magnet 26a, the second front magnet 26b, and the third front magnet 26c. However, this is not limited to this, and two magnets magnetized in the optical axis direction may be arranged so as to generate magnetic fields in opposite directions.

The first rear magnet group 23a and the first front magnet 26a, arranged side by side in the optical axis direction, form a first magnetic circuit. Similarly, the second rear magnet group 23b and the second front magnet 26b form a second magnetic circuit, and the third rear magnet group 23c and the third front magnet 26c form a third magnetic circuit.

The fixed part 20a further has a first restricting member 28, a second restricting member 29, and a cover 30. The rear yoke 22 has a first restricting part 22a, and the front yoke 25 has a second restricting part 25a. The movement of the movable part 20b is restricted within a predetermined range in the optical axis perpendicular plane 12c by the first restricting member 28, the second restricting member 29, the first restricting part 22a, the second restricting part 25a, the first column member 24a, the second column member 24b, and the third column member 24c. At the contact points of each of these parts that restrict the movement of the movable part 20b, a cushioning material such as rubber is provided to absorb the impact at the time of contact, thereby avoiding damage and reducing impact noise. The cover 30 prevents contact between the rear yoke 22 and a flexible printed circuit board such as a driving FPC 35 described later.

4 and 5 are exploded perspective views of the movable part 20b, and the direction in which the movable part 20b is viewed is different between FIG. 4 and FIG. 5. The movable part 20b has an image sensor holding member 31 and an image sensor 11. The image sensor 11 is fixed to the image sensor holding member 31 with adhesive or the like, the details of which will be described later. The movable part 20b also has a mask 32a, an infrared absorption filter 32b, an optical low pass filter 32c, and a vibration unit 32f. The mask 32a, the infrared absorption filter 32b, and the optical low pass filter 32c are held by a holder member 32d and a holder metal plate 32e, and are fixed to the image sensor 11 with an adhesive or the like. The mask 32a prevents unnecessary light from entering the image sensor 11 from outside the photographing optical path. The optical low pass filter 32c reduces moire caused by the repeated pattern of the subject. The vibration unit 32f is provided on the optical low-pass filter 32c and vibrates the optical low-pass filter 32 to remove foreign matter such as dust adhering to the surface of the optical low-pass filter 32c. Note that the principle and control of foreign matter removal by the vibration unit 32f are publicly known, so a detailed description will be omitted.

The movable part 20b further includes a first coil 33a, a second coil 33b, a third coil 33c, and a drive FPC 35. The drive FPC 35 is arranged so as to overlap the first coil 33a, the second coil 33b, and the third coil 33c on the optical axis projection plane (on the XY plane when viewed from the Z direction), and is fixed to the image sensor holding member 31 with an adhesive or the like.

The imaging element holding member 31 has a first recess 31a, a second recess 31b, and a third recess 31c. The first coil 33a is disposed inside the first recess 31a, the second coil 33b is disposed inside the second recess 31b, and the third coil 33c is disposed inside the third recess 31c, and are fixed to the imaging element holding member 31 with an adhesive or the like.

The first magnetic circuit and the first coil 33a form a VCM as a first actuator, the second magnetic circuit and the second coil 33b form a VCM as a second actuator, and the third magnetic circuit and the third coil 33c form a VCM as a third actuator. A Lorentz force is generated in a direction perpendicular to the magnetic field generated in the optical axis direction by the first magnetic circuit and the current flowing through the first coil 33a, and the resultant direction of the Lorentz force changes depending on the current direction of the first coil 33a. A similar Lorentz force is generated by the second magnetic circuit and the second coil 33b, and also by the third magnetic circuit and the third coil 33c. The first actuator and the second actuator generate a force (driving force) approximately parallel to the X direction, and the sum of the respective forces generates a translational force in the X direction, and the difference between the respective forces generates a rotational force around the optical axis. The third actuator generates a translational force in the Y direction.

The first detector 35a, the second detector 35b, and the third detector 35c are attached to the driving FPC 35. The first detector 35a is disposed inside the first coil 33a, the second detector 35b is disposed inside the second coil 33b, and the third detector 35c is disposed inside the third coil 33c. The first detector 35a, the second detector 35b, and the third detector 35c are, for example, Hall elements. The first detector 35a detects the magnetic force of the first magnetic circuit, and the first blur correction control unit 15a calculates position information (specifically, the position and angle around the optical axis) of the movable part 20b relative to the fixed part 20a in the optical axis perpendicular plane 12c based on the detection result. The same applies to the second detector 35b and the third detector 35c. The first coil 33a, the second coil 33b, and the third coil 33c are electrically connected to the drive FPC 35, and the first shake correction control unit 15a controls the current flowing through each coil via the drive FPC 35. In other words, the first shake correction control unit 15a controls the drive of the movable unit 20b by feedback control based on the deviation between the movement target value of the image sensor 11 based on the shake information detected by the first vibration detection unit 16a and the current position of the image sensor 11 detected by the Hall element.

The movable part 20b is biased against the fixed member 21 constituting the fixed part 20a by the magnetic attraction force generated between the rear yoke 22 and the thrust magnet 39 by the magnetic force of the thrust magnet 39 via the balls 36 (see Figures 2 and 3) which are rolling members. In other words, the rear yoke 22 and the thrust magnet 39 constitute a biasing part that biases the movable part 20b against the fixed part 20a. Note that in order to generate an attraction force between the rear yoke 22 and the thrust magnet 39, the rear yoke 22 needs to be a magnetic body (a member made of a magnetic material). Details of the biasing part will be described later.

The balls 36 are disposed inside the first enclosure 31d, the second enclosure 31e, and the third enclosure 31f provided on the imaging element holding member 31. When the movable part 20b moves in the optical axis perpendicular plane 12c relative to the fixed part 20a, the balls 36 roll, so that almost no load is generated due to friction between the balls and the imaging element holding member 31 and the fixed member 21. In addition, the movement of the movable part 20b in the direction opposite to the direction in which the rear yoke 22 and the thrust magnet 39 bias the movable part 20b is restricted by the front yoke 25 and the first restricting member 28. Therefore, even if an external force is applied to the imaging device 10 such that an impact is applied to pull the movable part 20b away from the fixed member 21, the movable part 20b will not fall off the fixed part 20a.

The movable part 20b is provided with a connecting member 38, which bridges the opening 31i of the image sensor holding member 31 and is fixed to the image sensor holding member 31 with screws 45 on both sides of the optical axis. The connecting member 38 has contact parts 38a at two locations, and the contact parts 38a come into contact with the first restricting part 22a of the rear yoke 22, restricting the movement of the movable part 20b within the plane 12c perpendicular to the optical axis to a certain range.

The thrust magnet 39 and thrust yoke 40 are fixed to the connecting member 38 with adhesive or the like, and the thrust magnet 39 is magnetized in the optical axis direction. Note that the thrust magnet 39 may be two-pole magnetized so that the magnetic fields of different directions are aligned in the Y direction, but it may also be a single-pole magnetized magnet.

The biasing portion formed by the rear yoke 22 and the thrust magnet 39 is arranged inside a triangle formed by three balls 36 arranged inside the first enclosure 31d, the second enclosure 31e, and the third enclosure 31f. As a result, a well-balanced biasing force can be generated for each ball 36.

Next, the biasing portion composed of the rear yoke 22 and the thrust magnet 39 will be described in detail. FIG. 6(a) and FIG. 7(a) are projection views of the biasing portion composed of the rear yoke 22 and the thrust magnet 39 when viewed from the subject side in the optical axis direction. Specifically, FIG. 6(a) shows an example of a state in which the movable portion 20b is within the vibration control range of the first blur correction unit 20 by the first blur correction control unit 15a, with the position of the thrust magnet 39 relative to the rear yoke 22. Meanwhile, FIG. 7(a) shows an example of a state in which the movable portion 20b protrudes outside the vibration control range of the first blur correction unit 20 by the first blur correction control unit 15a, with the position of the thrust magnet 39 relative to the rear yoke 22. FIG. 6(b) is a cross-sectional view taken along the line A-A in FIG. 6(a). FIG. 7(b) is a cross-sectional view taken along the line B-B in FIG. 7(a).

Since the thrust magnet 39 is fixed to the connecting member 38 that constitutes the movable part 20b, it moves relative to the rear yoke 22 as the movable part 20b moves. In FIG. 6(a), the area (range) in which the thrust magnet 39 can move corresponding to the vibration isolation control range of the first image stabilization unit 20 is shown by a dashed line as the movable area 41.

As shown in FIG. 6, the movable area 41 of the thrust magnet 39 does not extend beyond the end face of the rear yoke 22 on the optical axis projection plane. Therefore, the biasing force of the biasing portion acts only in the optical axis direction, not in a direction perpendicular to the optical axis 12a, and therefore the biasing portion does not reduce the vibration controllability of the first image stabilization unit 20 (i.e., the drive controllability of the movable portion 20b). Also, as shown in FIG. 7(b), if the thrust magnet 39 extends beyond the end of the rear yoke 22 on the optical axis projection plane, part of the biasing force of the biasing portion acts in a direction perpendicular to the optical axis 12a, but since it is outside the vibration control range, it does not affect the drive controllability of the movable portion 20b.

As described above, when the amount of movement of the movable part 20b from the reference position of the movable part 20b relative to the rear yoke 22 is greater than a predetermined value, part of the attractive force generated between the thrust magnet 39 and the rear yoke 22 acts as a force in the direction returning the movable part 20b to the reference position. On the other hand, when the amount of movement is not greater than the predetermined value, the attractive force does not act as a force in the direction returning the movable part to the reference position.

Next, we will explain the driving forces of the first to third actuators when the movable part 20b moves significantly within the plane 12c perpendicular to the optical axis. Figures 8(a) and 8(c) are projection views of the actuator 34 as viewed from the subject side in the optical axis direction, respectively, and show the coil 33. Figure 8(b) is a cross-sectional view taken along arrows C-C in Figure 8(a). Figure 8(d) is a cross-sectional view taken along arrows D-D in Figure 8(c).

The first and second actuators and the third actuator have the same function, but different directions of driving force generation, and are therefore referred to as "actuators 34." Similarly, the first to third coils 33a to 33c have the same function, and are therefore referred to as "coils 33." In addition, the first to third rear magnet groups 23a to 23c that face the first to third coils 33a to 33c in the optical axis direction are also referred to as "magnets 23."

When the movable part 20b moves relative to the fixed part 20a, the coil 33 constituting the actuator 34 moves relative to the magnet 23. Therefore, when the movable part 20b moves significantly relative to the fixed part 20a, the coil 33 also moves significantly relative to the magnet 23.

In the state shown in FIG. 8(a), the movable part 20b has moved in the plane perpendicular to the optical axis 12c to a position where one side of the coil 33 faces the magnetization switching point mb of the magnet 23. In the state shown in FIG. 8(c), where the movable part 20b has moved further from the state shown in FIG. 8(a), one side of the coil 33 does not face the magnet 23. In these cases, the return force of the actuator 34 attempting to return the movable part 20b to its original position (the position (reference position) where the blur correction amount is zero) is reduced.

However, when the movable part 20b moves significantly to the state shown in FIG. 7 where the thrust magnet 39 protrudes beyond the end of the rear yoke 22 in the plane perpendicular to the optical axis 12c, the component of the attractive force of the biasing part in the direction perpendicular to the optical axis 12a assists the returning force that returns the movable part 20b to its original position. In this way, the first blur correction control part 15a can obtain a sufficiently large returning force to return the movable part 20b to its original position without the need to increase the size of the actuator 34 or the current flowing through the coil 33.

Next, the relationship between gravity and the suction force of the biasing portion that supplements the thrust of the actuator 34 when returning the movable portion 20b to its original position will be described. Figure 9 is a projection view of the first image stabilization unit 20 when viewed from the subject side in the optical axis direction with the main body portion 10a turned off. Note that the cover 30 of the first image stabilization unit 20 is not shown in Figure 9.

When the imaging device 10 is turned off, the user typically places the imaging device 10 on a desk or the like so that the Y direction is the direction of gravity (so that the ZX plane is parallel to the horizontal direction). At this time, no current is applied to the first coil 33a, the second coil 33b, and the third coil 33c, so that the movable part 20b moves in the Y direction due to gravity, as shown in FIG. 9.

As described above, the connecting member 38 of the movable part 20b has two abutment parts 38a. Here, the position where the one of the two abutment parts 38a closer to the center of gravity 42 of the movable part 20b abuts the first restriction part 22a is defined as the abutment part 43. At this time, in the optical axis perpendicular plane 12c, a first moment 44a due to gravity centered on the abutment part 43 and a second moment 44b due to the return force of the biasing part are generated. The second moment 44b due to the return force of the biasing part is smaller than the first moment 44a due to gravity, and therefore, due to the balance with gravity, the movable part 20b is held in a state where the two abutment parts 38a abut the first restriction part 22a. As a result, the imaging element 11 does not tilt in the optical axis perpendicular plane 12c, and the performance of the imaging device 10 is not impaired.

Next, the structure for adhering and holding the imaging element 11 to the imaging element holding member 31 will be described below with reference to Figs. 10 and 11. In order to improve the image quality of the imaging device 10, it is desirable to improve the positional accuracy of the imaging element 11. Also, when considering the uses of the imaging device 10, it is desirable to improve the impact resistance under various conditions. To meet such requirements, the imaging element 11 is fixed to the imaging element holding member 31 by a first adhesive portion 51, which will be described below with reference to Fig. 10, and a second adhesive portion 52, which will be described below with reference to Fig. 11.

Figure 10(a) is a view (front view) of the movable part 20b seen from the subject side, and Figure 10(b) is a cross-sectional view taken along the arrow E-E in Figure 10(a). The imaging element 11 is held by the imaging element holding member 31 by bonding the inner periphery 31g of the imaging element holding member 31 to the back surface 11b of the imaging element 11 with a first adhesive part 51. The first adhesive part 51 is formed by hardening a first adhesive, and an ultraviolet-curable resin or the like is used for the first adhesive. By applying a liquid ultraviolet-curable resin to the adhesive part and irradiating it with ultraviolet light, the ultraviolet-curable resin is chemically changed to a solid. At that time, the imaging element holding member 31 and the first adhesive are bonded, and the first adhesive and the imaging element 11 are bonded, respectively, to form the first adhesive part 51, and the imaging element 11 is bonded to the imaging element holding member 31 and fixed.

As described above, the connecting member 38 is fastened to the imaging element holding member 31 by the screw 45. If the imaging element 11 is fixed to the imaging element holding member 31 by the first adhesive portion 51 and the second adhesive portion 52 and then the connecting member 38 is attached by the screw 45, the imaging element holding member 31 may be slightly deformed by the stress caused by the tightening torque of the screw 45. As a result, there is a concern that the imaging element 11 may become misaligned.

In order to avoid this problem, in this embodiment, as shown in FIG. 10(a), the first adhesive is applied to the upper and lower edges of the imaging element 11 and cured to form the first adhesive portion 51. As a result, the connecting member 38 extending in the left-right direction relative to the imaging element holding member 31 and the first adhesive portion 51 do not overlap when viewed from the optical axis direction (the direction perpendicular to the imaging surface 11a of the imaging element 11). As a result, the first adhesive can be applied and cured after the connecting member 38 is attached to the imaging element holding member 31 with the screw 45, so that it is possible to suppress positional deviation of the imaging element 11 and improve the positional accuracy of the imaging element 11. In addition, by performing adhesion in a pair of regions (regions along each of a pair of sides) sandwiching the center of the imaging element 11, the imaging element 11 can be stably fixed to the imaging element holding member 31.

Figure 11(a) is a view (front view) of the first image stabilization unit 20 as seen from the subject side. Figure 11(b) is a cross-sectional view taken along the arrows F-F in Figure 11(a). Figure 12 is an enlarged view of area 55 in Figure 11(b). From the standpoint of enhancing the impact resistance of the imaging device 10, it is desirable for the imaging element 11 to be firmly fixed to the imaging element holding member 31. Therefore, in the imaging device 10, the imaging element 11 is adhered and fixed to the imaging element holding member 31 by the second adhesive part 52 in addition to the first adhesive part 51.

The second adhesive forming the second adhesive portion 52 can be an ultraviolet-curable resin or the like, as with the first adhesive forming the first adhesive portion 51. As shown in FIG. 11(a), the second adhesive is applied to the left and right sides of the imaging element 11. At that time, as shown in FIG. 11(c), the second adhesive is applied between the side wall portion 31h of the imaging element holding member 31 and the side portion 11c of the imaging element 11, and then cured to form the second adhesive portion 52, and the imaging element 11 is adhered and fixed to the imaging element holding member 31.

In this way, in the imaging device 10, the top and bottom sides of the imaging element 11 are bonded with the first adhesive portion 51, and the left and right sides of the imaging element 11 are bonded with the second adhesive portion 52, and the first adhesive portion 51 and the second adhesive portion 52 are arranged so that they do not overlap when viewed from the optical axis direction. In addition, the back portion 11b of the imaging element 11 is bonded with the first adhesive portion 51, and the side portion 11c of the imaging element 11 is bonded with the second adhesive portion 52. By adopting such a configuration, it is possible to maintain the position of the imaging element 11 relative to the imaging element holding member 31 with high precision even if the imaging device 10 is subjected to impacts (external forces) from various directions.

Next, the differences between the first adhesive portion 51 and the second adhesive portion 52 will be described. The first adhesive portion 51 adheres the imaging element 11 to the imaging element holding member 31 over a wide area so as to cover both the rear portion 11b of the imaging element 11 and the inner periphery 31g of the imaging element holding member 31. Therefore, if a first adhesive with low viscosity is used, the first adhesive may spread to the rear portion 11b during application, resulting in a shallow application to the inner periphery 31g. Therefore, it is desirable to use a high-viscosity adhesive for the first adhesive portion 51 so as to cover both the rear portion 11b and the inner periphery 31g.

On the other hand, as described above, the second adhesive portion 52 is formed between the side wall portion 31h of the image sensor holding member 31 and the side surface portion 11c of the image sensor 11. Here, as shown in FIG. 12, it is necessary to provide a gap X1 between the movable portion 20b and the fixed portion 20a in order to ensure the movable area of the movable portion 20b. Also, in order to hold the image sensor 11 at the side surface, it is necessary to provide a space for applying the second adhesive and a width X2 equivalent to the thickness of the side wall portion 31h of the image sensor holding member 31 on the inside. In order to reduce the size of the first image stabilization unit 20, it is desirable to reduce the width X2, and considering that the adhesive is poured into such a narrow area, it is desirable to use an adhesive with a low viscosity for the second adhesive.

As such, it is desirable to use a second adhesive with a lower viscosity than the first adhesive. Also, since the first adhesive is applied over a wider area than the second adhesive, it is desirable to use the first adhesive portion 51 as the main adhesive portion and the second adhesive portion 52 as the secondary adhesive portion.

In addition, since it is expected that the imaging device 10 will be used in various temperature environments, it is desirable to obtain high impact resistance even in various temperature environments. Here, taking into consideration that the adhesive strength of the adhesive is temperature dependent, it is desirable to combine adhesives having different temperature characteristics for the adhesive strength in the first adhesive portion 51 and the second adhesive portion 52.

Fig. 13 is a diagram for explaining an example of selection of the first adhesive part 51 and the second adhesive part 52, taking into consideration the temperature characteristics of the adhesive strength. In Fig. 13, the horizontal axis represents temperature T and the vertical axis represents adhesive strength P, with curve _P51 showing the temperature-adhesive strength characteristics of the first adhesive part 51 and curve _P52 showing the temperature-adhesive strength characteristics of the second adhesive part 52. In addition, the solid line _P51 + _P52 shows the sum of curve _P51 and curve _P52 , that is, the temperature characteristics of the overall adhesive strength of the imaging element 11 to the imaging element holding member 31.

As shown in FIG. 13, by combining a first adhesive part 51 that is resistant to high temperatures with a second adhesive part 52 that is resistant to low temperatures, it is possible to realize a holding mechanism for the imaging element 11 that is highly resistant to impacts over a wide temperature range. Note that when the imaging device 10 is in use, the temperature near the imaging element 11 is likely to rise due to the effects of heat generation from the imaging element 11, so it is desirable to use an adhesive that exhibits high adhesive strength on the high temperature side for the first adhesive part 51, which is the main adhesive part.

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

For example, it is sufficient that one of the magnets and coils that make up the VCM, which is the actuator, is located in the fixed part and the other in the movable part. Also, it is sufficient that one of the thrust magnets and rear yoke that make up the biasing part is located in the fixed part and the other in the movable part.

In addition, when the connecting member is arranged to extend in the vertical direction, the first adhesive portion may be arranged on the left and right sides, and the second adhesive may be arranged on the top and bottom sides. In addition, when the imaging element holding member forms three sides when viewed from the optical axis direction, and the connecting member is attached to the remaining side to form an opening, the first adhesive portion may be applied at a position that does not overlap with the connecting member when viewed from the optical axis direction.

REFERENCE SIGNS LIST 10 Imaging device 11 Imaging element 11b Rear portion 14 Camera control portion 15a First blur correction control portion 20 First blur correction unit 20a Fixed portion 20b Movable portion 22 Rear yoke 22a First restriction portion 23a First rear magnet group 26a First front magnet 31 Imaging element holding member 33a First coil 34 Actuator 36 Ball 38 Connecting member 39 Thrust magnet 51 First adhesive portion 52 Second adhesive portion 60 Second blur correction unit

Claims (20)

A fixed portion;
A movable part that is arranged to be movable relative to the fixed part within a predetermined range in a plane;
A plurality of rolling members disposed between the fixed portion and the movable portion;
An actuator that drives the movable part;
and a biasing means for biasing the movable portion against the fixed portion via the rolling member,
The biasing means includes a magnet and a magnetic body.
one of the magnet and the magnetic body is held by the movable part, and the other is held by the fixed part;
a range in which the magnet can move relative to the magnetic body when the actuator is driven to move the movable part does not extend beyond an end of the magnetic body when viewed from a direction perpendicular to the plane ;
A driving device characterized in that when the magnet protrudes from the end of the magnetic body when viewed from a direction perpendicular to the plane, the biasing force of the biasing means in a direction parallel to the plane is greater than when the magnet does not protrude from the end of the magnetic body . the magnetic body has a restricting portion that restricts movement of the movable portion,
2. The drive device according to claim 1, wherein among moments generated within the plane about the contact point between the movable portion and the regulating portion, a moment generated by gravity is larger than a moment generated by the biasing means. The movable portion and the restricting portion contact each other at two points.
The drive device according to claim 2, characterized in that, among the moments generated within the plane centered on one of the two contact points that is closer to the center of gravity of the movable part, the moment generated by gravity is greater than the moment generated by the biasing means. At least three of the rolling members are arranged,
4. The drive device according to claim 1 , wherein the biasing means is disposed inside a triangle formed by the rolling members. A control means for controlling the driving of the actuator is provided,
The actuator comprises:
A coil held by the movable part;
A magnet held by the fixed portion;
A current supplying means for supplying a current to the coil;
a first detection means for detecting blur information of the fixed portion;
and a second detection means for detecting relative position information of the movable part with respect to the fixed part,
5. The driving device according to claim 1 , wherein the control means controls driving of the movable part by controlling a current flowing through the coil based on the shake information and the position information. A fixed portion;
A movable part that is arranged to be movable relative to the fixed part within a predetermined range in a plane;
A plurality of rolling members disposed between the fixed portion and the movable portion;
An actuator that drives the movable part;
and a biasing means for biasing the movable portion against the fixed portion via the rolling member,
The biasing means includes a magnet and a magnetic body.
one of the magnet and the magnetic body is held by the movable part, and the other is held by the fixed part;
A driving device characterized in that when the amount of movement of the movable part from a reference position of the movable part relative to the fixed part is greater than a predetermined value, a portion of the attractive force generated between the magnet and the magnetic body acts as a force in a direction returning the movable part to the reference position, and when the amount of movement is greater than 0 and not greater than the predetermined value, the attractive force does not act as a force in a direction returning the movable part to the reference position. A drive device according to any one of claims 1 to 6 ,
an imaging element held by a movable part of the driving device,
The image stabilization device according to claim 1, wherein the movable portion is capable of moving in a direction parallel to an imaging surface of the imaging element and rotating within a plane parallel to the imaging surface. A drive device according to any one of claims 1 to 6 ,
a blur correction lens held by a movable part of the drive device,
an optical axis of the image stabilization lens, the optical axis being perpendicular to the optical axis of the image stabilization lens; An imaging apparatus comprising the image blur correction device according to claim 7 or 8 . A lens barrel comprising the image blur correction device according to claim 8 . An imaging element;
A holding member for holding the imaging element;
a connecting member that forms at least one opening when connected to the holding member;
a first adhesive portion provided between a rear portion of the imaging element and an inner periphery of the holding member;
10. The imaging device according to claim 9, wherein the connecting member and the first adhesive portion do not overlap when viewed from a direction perpendicular to the imaging surface of the imaging element. 12. The imaging device according to claim 11 , wherein the first adhesive portion is provided in a pair of regions sandwiching a center of the imaging element in a plane parallel to the imaging surface. 13. The imaging device according to claim 11 , further comprising a second adhesive portion provided between a side surface of the imaging element and a side wall of the holding member. 14. The imaging device according to claim 13 , wherein the second adhesive portion is provided in a pair of regions sandwiching a center of the imaging element in a plane parallel to the imaging surface. 15. The imaging device according to claim 13 , wherein the first adhesive portion and the second adhesive portion do not overlap when viewed from a direction perpendicular to the imaging surface of the imaging element. 16. The imaging device according to claim 13 , wherein the first adhesive portion and the second adhesive portion have different characteristics. 17. The imaging device according to claim 16 , wherein the first adhesive portion and the second adhesive portion have different temperature characteristics of adhesive strength. 18. The imaging device according to claim 17 , wherein the first adhesive portion has a higher adhesive strength at high temperatures than the second adhesive portion. 19. The imaging device according to claim 13, wherein a first liquid adhesive used to form the first adhesive portion and a second liquid adhesive used to form the second adhesive portion have different viscosities when applied to the imaging element and the holding member. 20. The imaging device according to claim 19 , wherein the viscosity of the second adhesive is lower than the viscosity of the first adhesive.