Drive device, imaging device, and lens barrel

Abstract

To provide a driving device that has reduced a load on an actuator that drives a movable part while reducing a return force to the center when moving the movable part with respect to a stationary part.SOLUTION: A driving device comprises: a first shake correction unit 20 and a stationary part 20a; a movable part 20b arranged movably within a predetermined range in a plane; and an urging part that urges the movable part 20b against the stationary part 20a with a ball 36 therebetween. The urging part is formed of a rear yoke 22 held in the stationary part 20a and a thrust magnet 39 held in the movable part 20b. A range in which the thrust magnet 39 is movable in driving an actuator to move the movable part is determined to be a range that does not protrude from the ends of the rear yoke 22 when seen from a direction orthogonal to a plane on which the movable part 20b is movable.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a driving device, an imaging device, and a lens barrel, and particularly to an imaging device and a lens barrel including a driving device using a voice coil motor.

Background Art

[0002] Conventionally, a driving device that moves a movable part in a plane with respect to a fixed part is known, and as a configuration for generating a driving force for driving the movable part, there is a configuration called a voice coil motor (VCM) method.

[0003] In the VCM method, a magnet is disposed on one of the movable part and the fixed part, and a coil is disposed on the other, and a driving force is generated by energizing the coil in a magnetic circuit formed by the magnet. As an application example of such a driving device, there is a shake correction mechanism mounted on an imaging device. In the shake correction mechanism, an imaging element or a shake correction lens is mounted on the movable part, and the movable part is driven so as to cancel out the shake based on the amount of shake detected by a predetermined sensor.

[0004] In a shake correction mechanism adopting the VCM method, usually, a plurality of balls are disposed between the movable part and the fixed part so as to be rollable, thereby reducing the contact resistance and enabling smooth driving. At this time, as a method of sandwiching the balls between the movable part and the fixed part so that the balls surely contact the movable part and the fixed part, a method of attracting the fixed part and the movable part using a spring or a magnet is used (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, when shooting while walking using an imaging device, the amount of blur increases, and thus a blur correction device capable of canceling such a large amount of blur is required. The blur correction device of the imaging device can correct a larger amount of blur by increasing the amount of movement of the movable part relative to the fixed part.

[0007] In response to such problems, in the technologies described in Patent Documents 1 and 2 above, magnets and magnetic bodies are used as means for attracting the movable part and the fixed part to each other. However, as the amount of movement (moving distance) increases, a return force toward the center due to magnetic force is generated. This return force can quickly return to a state where blur correction is not performed, but on the other hand, there is a problem that it increases the driving load when performing blur correction.

[0008] An object of the present invention is to provide a driving device that reduces the return force toward the center when moving the movable part relative to the fixed part and suppresses the load on the actuator that drives the movable part.

Means for Solving the Problems

[0009] The driving device according to the present invention includes 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 that drives the movable part, and biasing means that biases the movable part with respect to the fixed part via the rolling members. 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. When driving the actuator to move the movable part, the magnet relative to the magnetic body The movable range does not protrude from the end of the magnetic body when viewed from a direction perpendicular to the plane before This is characterized by not, when viewed from a direction perpendicular to the plane, in a state where the magnet protrudes from the end of the magnetic body, the biasing force of the biasing means in the direction parallel to the plane is greater than in a state where the magnet does not protrude from the end of the magnetic body being characterized by.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a drive device that reduces the return force to the center when moving the movable part with respect to the fixed part and suppresses the load on the actuator that drives the movable part.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, a configuration in which the drive device according to the present invention is applied to an image blur correction device of an imaging device will be described as an example, but the application examples of the drive device according to the present invention are not limited to imaging devices.

[0013] FIG. 1 is a diagram for explaining a 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 includes an imaging device main body 10a (hereinafter referred to as "main body portion 10a") and a lens barrel 10b that is detachable from the main body portion 10a.

[0014] The main body portion 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.

[0015] A virtual ray representative of the light beam irradiated onto the imaging surface 11a of the imaging element 11 through the imaging optical system 12 is referred to as an "imaging optical axis 12a" (hereinafter referred to as "optical axis 12a"), and a plane orthogonal to the optical axis 12a is referred to as an "optical axis orthogonal plane" (hereinafter referred to as "optical axis orthogonal plane 12c"). The optical axis 12a passes through the center of the imaging surface 11a and is orthogonal to the imaging surface 11a. Further, 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, X, Y, and Z directions orthogonal to each other are defined. The Z direction is a direction 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 both the X direction and the Z direction are in the horizontal plane, the Y direction becomes the vertical direction. Therefore, the optical axis orthogonal plane 12c is the XY plane.

[0016] The imaging element 11 is composed of a photoelectric conversion element such as a CMOS image sensor or a CCD image sensor, and is arranged with its imaging surface 11a facing the subject side (the lens barrel 10b side) so that the imaging surface 11a is orthogonal to the optical axis 12a. The imaging element 11 generates an image signal by photoelectrically converting the optical image of the subject formed by the imaging optical system 12 on the imaging surface 11a. The image signal generated by the imaging element 11 is converted into image data by performing various processes in the image processing unit 17 and is stored in a memory (storage device) not shown. The camera control unit 14 is an arithmetic means in a main IC not shown, receives an input operation from a user via an operation means not shown, and controls the overall operation of the imaging device 10.

[0017] The imaging optical system 12 is composed of a lens group not shown disposed inside the lens barrel 10b, and forms a 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 arrange the imaging element 11 with high positional accuracy with respect 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. Further, the lens barrel 10b is connected to the base member 13c via a lens-side mount member 13b and a main body-side mount member 13a.

[0018] The first shake correction unit 20 corrects image blur caused by shake generated in the imaging device 10 by moving the imaging element 11 in a direction orthogonal to the optical axis or rotating it within the plane 12c orthogonal to the optical axis, thereby making it possible to obtain a clear subject image. 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, resulting in blur in the image obtained through the imaging element 11. At this time, when the change in the 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 regarded as translational or rotational movement (image plane blur) within the plane 12c orthogonal to the optical axis. Therefore, by translating or rotating the imaging element 11 within the plane 12c orthogonal to the optical axis so as to cancel this image plane blur, a clear subject image with corrected image blur can be obtained. Note that a configuration may be adopted in which movement in a direction orthogonal to the imaging surface is also performed when the imaging element 11 is moved in a direction parallel to the imaging surface.

[0019] Similarly, the second shake correction unit 60 corrects image blur caused by shake generated in the imaging device 10 by moving the shake correction lens 12b in a direction orthogonal to the optical axis or rotating it within the plane 12c orthogonal to the optical axis, thereby making it possible to obtain a clear subject image. That is, by moving the shake correction lens 12b in a direction orthogonal to the optical axis, the optical axis 12a is refracted. At this time, the shake correction lens 12b is moved in a direction orthogonal to the optical axis so as to cancel the image plane blur. Thereby, a clear subject image with corrected image blur can be obtained. Note that since the principle of shake correction by moving the imaging element 11 or the shake correction lens 12b is known, a more detailed description will be omitted. Also, a configuration may be adopted in which movement in the optical axis direction is also performed when the shake correction lens 12b is moved in a direction orthogonal to the optical axis.

[0020] The first shake correction unit 20 generally includes a fixed part, a movable part, and a plurality of driving force generating parts. The fixed part is fixed to the base member 13c, and the movable part holds the imaging element 11. The movable part is supported by the fixed part with three degrees of freedom and can move in a direction orthogonal to the optical axis and rotate within the plane 12c orthogonal to the optical axis relative to the fixed part. That is, the first shake correction unit 20 is configured as a driving device (so-called XYθ stage) capable of driving control in three axes, and it is possible to move the imaging element 11 in a direction orthogonal to the optical axis and rotate it within the plane 12c orthogonal to the optical axis.

[0021] The second shake correction unit 60 generally includes a fixed part, a movable part, and a plurality of driving force generating parts. The fixed part is fixed to a housing (not shown) of the lens barrel 10b, and the movable part holds the shake correction lens 12b. The movable part is supported by the fixed part with two degrees of freedom and can move in a direction orthogonal to the optical axis relative to the fixed part. That is, the second shake correction unit 60 is configured as a driving device (so-called XY stage) capable of driving control in two axes, and it is possible to move the shake correction lens 12b in a direction orthogonal to the optical axis.

[0022] 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 for detecting the angular velocity, acceleration, etc. 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 each calculate the amount of angular change and movement in each direction of the imaging device 10 as shake information by integrating the angular velocity and acceleration detected by the first vibration detection unit 16a and the second vibration detection unit 16b. Further, 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 movement of the imaging element 11 by controlling the driving of the first shake correction unit 20. Similarly, the second shake correction control unit 15b calculates a movement target value of the shake correction lens 12b based on the shake information detected by the second vibration detection unit 16b, and controls the movement of the shake correction lens 12b by controlling the driving of the second shake correction unit 60.

[0023] Note that the imaging device 10 may be configured to include only one of the first shake correction unit 20 and the second shake correction unit 60. When the first shake correction unit 20 is not provided, the imaging element 11 is fixedly arranged with respect to the optical axis 12a. When the second shake correction unit 60 is not provided, basically the shake correction lens 12b becomes unnecessary. That is, the imaging optical system 12 of the lens barrel 10b is designed so that desired optical characteristics can be obtained with a lens configuration that does not include the shake correction lens 12b.

[0024] Next, the detailed configuration of the first shake correction unit 20 will be described. Note that the configuration of the second shake correction unit 60 is omitted because it follows the configuration of the first shake correction unit 20.

[0025] FIGS. 2 and 3 are exploded perspective views of the first shake correction unit 20, and the viewing directions of the first shake correction unit 20 are different between FIGS. 2 and 3. The first shake correction unit 20 includes a fixed part 20a and a movable part 20b. In FIGS. 2 and 3, the movable part 20b is shown without being disassembled, and the fixed part 20a is shown disassembled.

[0026] The fixed part 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 arranged so as to be surrounded by the first opening 21a, the second opening 21b, and the third opening 21c.

[0027] In the present embodiment, as the first rear magnet group 23a, the second rear magnet group 23b, and the third rear magnet group 23c, two magnets magnetized in the optical axis direction (Z direction) are arranged so as to generate magnetic fields in opposite directions. However, the present invention is not limited to this, and one magnet magnetized in two poles may be used.

[0028] The fixing part 20a also has a first column member 24a, a second column member 24b, a third column 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 fixing member 21 with screws via the first column member 24a, the second column member 24b, and the third column 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.

[0029] In the present embodiment, one magnet magnetized in two poles is used as the first front magnet 26a, the second front magnet 26b, and the third front magnet 26c. However, the present invention 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.

[0030] 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.

[0031] The fixed part 20a further includes a first regulating member 28, a second regulating member 29, and a cover 30. The rear yoke 22 has a first regulating part 22a, and the front yoke 25 has a second regulating part 25a. The movement of the movable part 20b is regulated within a predetermined range in the plane 12c perpendicular to the optical axis by the first regulating member 28, the second regulating member 29, the first regulating part 22a, the second regulating part 25a, the first pillar member 24a, the second pillar member 24b, and the third pillar member 24c. At the contact portions of these parts that regulate the movement of the movable part 20b, a cushioning material such as rubber for absorbing the impact during contact is provided to avoid damage and reduce impact noise. The cover 30 prevents contact between a flexible printed circuit board such as the drive FPC 35 described later and the rear yoke 22.

[0032] FIGS. 4 and 5 are exploded perspective views of the movable part 20b, and the viewing directions of the movable part 20b in FIGS. 4 and 5 are different. The movable part 20b includes 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 an adhesive or the like, and the details thereof will be described later. Further, the movable part 20b includes 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 sheet metal 32e, and are fixed to the image sensor 11 with an adhesive member or the like. The mask 32a prevents unnecessary light from entering the image sensor 11 from outside the imaging optical path. The optical low-pass filter 32c reduces moire caused by the repeating pattern of the subject. The vibration unit 32f is provided on the optical low-pass filter 32c and removes foreign matters such as dust attached to the surface of the optical low-pass filter 32c by vibrating the optical low-pass filter 32. Since the principle and control of foreign matter removal by the vibration unit 32f are well known, detailed description thereof is omitted.

[0033] The movable part 20b further includes a first coil 33a, a second coil 33b, a third coil 33c, and a driving FPC 35. The driving 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.

[0034] The image sensor 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 each fixed to the image sensor holding member 31 with an adhesive or the like.

[0035] 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 orthogonal 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 force direction of the Lorentz force changes according to the energization direction of the first coil 33a. Similar Lorentz forces are also generated in the second magnetic circuit and the second coil 33b, and in the third magnetic circuit and the third coil 33c. The first actuator and the second actuator generate forces (driving forces) substantially parallel to the X direction, and a translational force in the X direction is generated by the sum of the respective forces, and a rotational force around the optical axis is generated by the difference between the respective forces. The third actuator generates a translational force in the Y direction.

[0036] The drive FPC 35 is attached with a first detector 35a, a second detector 35b, and a third detector 35c. 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, respectively. 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 based on the detection result, the first shake correction control unit 15a calculates the position information (specifically, the position and the angle around the optical axis) of the movable part 20b in the plane 12c orthogonal to the optical axis with respect to the fixed part 20a. 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. That is, the first shake correction control unit 15a controls the drive of the movable part 20b by feedback control based on the deviation between the movement target value of the imaging element 11 based on the shake information detected by the first shake detection unit 16a and the current position of the imaging element 11 detected by the Hall element.

[0037] The movable part 20b is biased to the fixing member 21 constituting the fixed part 20a by the attractive force generated between the rear yoke 22 and the thrust magnet 39 by the magnetic force of the thrust magnet 39 via the ball 36 (see FIGS. 2 and 3) which is a rolling member. In other words, the rear yoke 22 and the thrust magnet 39 constitute a biasing part that biases the movable part 20b with respect to the fixed part 20a. Note that in order to generate an attractive 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.

[0038] The ball 36 is respectively disposed inside the first enclosure portion 31d, the second enclosure portion 31e, and the third enclosure portion 31f provided on the imaging element holding member 31. When the movable portion 20b moves within the plane 12c orthogonal to the optical axis with respect to the fixed portion 20a, the ball 36 rolls, so that almost no load is generated due to the friction between the ball and the imaging element holding member 31 and the fixed member 21. Further, the movement of the movable portion 20b in the direction opposite to the direction in which the biasing portion formed by the rear yoke 22 and the thrust magnet 39 biases the movable portion 20b is restricted by the front yoke 25 and the first restricting member 28. Therefore, even if an impact is applied to the imaging device 10 and an external force that pulls the movable portion 20b away from the fixed member 21 is applied, the movable portion 20b does not drop off from the fixed portion 20a.

[0039] The movable portion 20b includes a connecting member 38. The connecting member 38 bridges the opening 31i of the imaging element holding member 31 and is fixed to the imaging element holding member 31 with screws 45 on both sides sandwiching the optical axis. Two contact portions 38a are provided on the connecting member 38. By the contact portion 38a contacting the first restricting portion 22a of the rear yoke 22, the movement of the movable portion 20b within the plane 12c orthogonal to the optical axis is restricted to a certain range.

[0040] The thrust magnet 39 and the thrust yoke 40 are fixed to the connecting member 38 with an adhesive or the like. The thrust magnet 39 is magnetized in the optical axis direction. Note that, as the thrust magnet 39, one magnetized in two poles such that magnetic fields in different directions are arranged in the Y direction can be used, or one magnetized in a single pole can also be used.

[0041] The biasing portion constituted by the rear yoke 22 and the thrust magnet 39 is disposed inside a triangle formed by the three balls 36 respectively disposed inside the first enclosure portion 31d, the second enclosure portion 31e, and the third enclosure portion 31f. As a result, a biasing force can be generated in a well-balanced manner with respect to each ball 36.

[0042] Next, the biasing portion composed of the rear yoke 22 and the thrust magnet 39 will be described in detail. FIGS. 6(a) and 7(a) are respectively projection views of the biasing portion composed of the rear yoke 22 and the thrust magnet 39 as viewed from the subject side in the optical axis direction. Specifically, FIG. 6(a) shows an example of a state where the movable portion 20b is within the anti-shake control range of the first shake correction unit 20 by the first shake correction control unit 15a, represented by the position of the thrust magnet 39 with respect to the rear yoke 22. On the other hand, FIG. 7(a) shows an example of a state where the movable portion 20b protrudes outside the anti-shake control range of the first shake correction unit 20 by the first shake correction control unit 15a, represented by the position of the thrust magnet 39 with respect to the rear yoke 22. FIG. 6(b) is a cross-sectional view taken along the arrow A-A shown in FIG. 6(a). FIG. 7(b) is a cross-sectional view taken along the arrow B-B shown in FIG. 7(a).

[0043] Since the thrust magnet 39 is fixed to the connecting member 38 that constitutes the movable portion 20b, it moves relative to the rear yoke 22 as the movable portion 20b moves. In FIG. 6(a), a region (range) where the thrust magnet 39 can move corresponding to the anti-shake control range of the first shake correction unit 20 is represented by a broken line as the movable region 41.

[0044] As shown in FIG. 6, the movable region 41 of the thrust magnet 39 does not protrude from the end face of the rear yoke 22 on the optical axis projection plane. Therefore, the biasing force by the biasing portion acts only in the optical axis direction and does not act in the direction orthogonal to the optical axis 12a. Thus, the biasing portion does not reduce the anti-shake controllability of the first shake correction unit 20 (that is, the drive controllability of the movable portion 20b). Also, as shown in FIG. 7(b), when the thrust magnet 39 protrudes from the end of the rear yoke 22 on the optical axis projection plane, a part of the biasing force by the biasing portion acts in the direction orthogonal to the optical axis 12a, but since it is outside the anti-shake control range, it does not affect the drive controllability of the movable portion 20b.

[0045] As described above, when the amount of movement of the movable part 20b from the reference position of the movable part 20b with respect to the rear yoke 22 is larger than a predetermined value, a part of the attractive force generated between the thrust magnet 39 and the rear yoke 22 acts as a force in the direction of returning the movable part 20b to the reference position. One side When the amount of movement is not larger than the predetermined value, the attractive force does not act as a force in the direction of returning the movable part to the reference position.

[0046] Subsequently, the driving forces of the first to third actuators when the movable part 20b moves greatly within the plane 12c orthogonal to the optical axis will be described. FIGS. 8(a) and 8(c) are respectively projection views of the actuator 34 as viewed from the subject side in the optical axis direction, and the coil 33. FIG. 8(b) is a cross-sectional view taken along the line C-C shown in FIG. 8(a). FIG. 8(d) is a cross-sectional view taken along the line D-D shown in FIG. 8(c).

[0047] Note that the first and second actuators and the third actuator have the same function although the directions in which the driving forces are generated are different, and thus these are referred to as the "actuator 34". Similarly, since the first to third coils 33a to 33c also have the same function, these are referred to as the "coil 33". Further, the first to third coils 33a to 33c and the first to third rear magnet groups 23a to 23c that face each other in the optical axis direction are also referred to as the "magnet 23".

[0048] 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 greatly relative to the fixed part 20a, the coil 33 also moves greatly relative to the magnet 23.

[0049] In the state shown in FIG. 8(a), the movable part 20b has moved within the plane 12c orthogonal to the optical axis to a position where one side of the coil 33 faces the switching mb of the magnetization of the magnet 23. In the state shown in FIG. 8(c) where the movable part 20b has moved further from the state of FIG. 8(a), one side of the coil 33 does not face the magnet 23. In these cases, the restoring force with which the actuator 34 tries to return the movable part 20b to its original position (the position where the shake correction amount is zero (reference position)) decreases.

[0050] However, when the movable part 20b has moved greatly to the state of FIG. 7 where the thrust magnet 39 protrudes from the end of the rear yoke 22 within the plane 12c orthogonal to the optical axis, the component of the attractive force of the biasing part in the direction orthogonal to the optical axis 12a assists the restoring force that returns the movable part 20b to its original position. Thus, the first shake correction control unit 15a can obtain a sufficiently large restoring force for returning the movable part 20b to its original position without the need to increase the size of the actuator 34 or increase the current flowing through the coil 33.

[0051] Next, the relationship between the attractive force of the biasing part that assists the thrust of the actuator 34 when returning the movable part 20b to its original position and gravity will be described. FIG. 9 is a projection view when the first shake correction unit 20 in a state where the main body part 10a is not powered is viewed from the subject side in the optical axis direction. Note that in FIG. 9, the cover 30 provided in the first shake correction unit 20 is not shown.

[0052] When the power of the imaging device 10 is off, the user generally places the imaging device 10 on a desk or the like so that the Y direction becomes the direction of gravity (so that the ZX plane is parallel to the horizontal direction). At this time, since no current is supplied to the first coil 33a, the second coil 33b, and the third coil 33c, as shown in FIG. 9, the movable part 20b moves in the Y direction due to gravity.

[0053] As described above, the connecting member 38 of the movable part 20b has two contact parts 38a. Here, the position where the closer one of the two contact parts 38a to the center of gravity 42 of the movable part 20b contacts the first regulating part 22a is defined as the contact point 43. At this time, in the plane 12c orthogonal to the optical axis, a first moment 44a due to gravity centered on the contact point 43 and a second moment 44b due to the restoring force of the biasing part are generated. The second moment 44b due to the restoring force of the biasing part is smaller than the first moment 44a due to gravity. Therefore, due to the balance with gravity, the movable part 20b is held in a state where the two contact parts 38a contact the first regulating part 22a. As a result, since the imaging element 11 does not tilt within the plane 12c orthogonal to the optical axis, the performance of the imaging device 10 is not impaired.

[0054] Next, the structure in which the imaging element 11 is adhered and held 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 position accuracy of the imaging element 11. Also, considering the use of the imaging device 10, it is desirable to enhance the shock resistance under various situations. To meet such requirements, the imaging element 11 is fixed to the imaging element holding member 31 by a first adhesive part 51 described with reference to FIG. 10 and a second adhesive part 52 described with reference to FIG. 11, which will be described below.

[0055] FIG. 10(a) is a view (front view) of the movable part 20b seen from the subject side, and FIG. 10(b) is a cross-sectional view taken along the line E-E shown in FIG. 10(a). The imaging element 11 is held by the imaging element holding member 31 by being adhered between the inner peripheral part 31g of the imaging element holding member 31 and the back surface part 11b of the imaging element 11 by the first adhesive part 51. The first adhesive part 51 is formed by curing a first adhesive, and an ultraviolet curable resin or the like is adopted as the first adhesive. By applying a liquid ultraviolet curable resin to the adhesive part and irradiating it with ultraviolet rays, the ultraviolet curable resin chemically changes into 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 respectively bonded to form the first adhesive part 51, and the imaging element 11 is adhered and fixed to the imaging element holding member 31.

[0056] Note that, as described above, the connecting member 38 is fastened to the image sensor holding member 31 with screws 45. If the connecting member 38 is attached with screws 45 after the image sensor 11 is fixed to the image sensor holding member 31 by the first adhesive portion 51 and the second adhesive portion 52, the image sensor holding member 31 may be slightly deformed by the stress caused by the tightening torque of the screws 45. As a result, there is a concern that displacement may occur in the image sensor 11.

[0057] In order to avoid this problem, in the present embodiment, as shown in FIG. 10(a), the first adhesive is applied to the upper side and the lower side of the image sensor 11 and cured, whereby the first adhesive portion 51 is formed. Thereby, the connecting member 38 extending in the left-right direction with respect to the image sensor holding member 31 and the first adhesive portion 51 are configured not to overlap when viewed from the optical axis direction (the direction orthogonal to the imaging surface 11a of the image sensor 11). Thereby, after the connecting member 38 is attached to the image sensor holding member 31 with the screw 45, the first adhesive can be applied and cured, so that displacement of the image sensor 11 can be suppressed and the positional accuracy of the image sensor 11 can be improved. Further, by performing adhesion in a pair of regions (regions along each side of the pair) sandwiching the center of the image sensor 11, the image sensor 11 can be stably fixed to the image sensor holding member 31.

[0058] FIG. 11(a) is a view (front view) of the first shake correction unit 20 as viewed from the subject side. FIG. 11(b) is a cross-sectional view taken along the line F-F shown in FIG. 11(a). FIG. 12 is an enlarged view of the region 55 in FIG. 11(b). From the viewpoint of enhancing the shock resistance of the imaging device 10, it is desirable that the image sensor 11 is firmly fixed to the image sensor holding member 31. Therefore, in the imaging device 10, in addition to the first adhesive portion 51, the image sensor 11 is also adhered and fixed to the image sensor holding member 31 by the second adhesive portion 52.

[0059] As with the first adhesive for forming the first bonding portion 51, an ultraviolet curable resin or the like can be used as the second adhesive for forming the second bonding portion 52. As shown in FIG. 11(a), the second adhesive is applied to the left and right sides of the imaging element 11. At this time, as shown in FIG. 11(c), after the second adhesive is applied between the side wall portion 31h of the imaging element holding member 31 and the side surface portion 11c of the imaging element 11 and then cured, the second bonding portion 52 is formed, and the imaging element 11 is adhered and fixed to the imaging element holding member 31.

[0060] Thus, in the imaging device 10, the upper and lower sides of the imaging element 11 are adhered by the first bonding portion 51, the left and right sides of the imaging element 11 are adhered by the second bonding portion 52, and the first bonding portion 51 and the second bonding portion 52 are arranged so as not to overlap when viewed from the optical axis direction. Further, the back surface portion 11b of the imaging element 11 is adhered by the first bonding portion 51, and the side surface portion 11c of the imaging element 11 is adhered by the second bonding portion 52. By adopting such a configuration, even when impacts (external forces) from various directions are applied to the imaging device 10, it is possible to hold the position of the imaging element 11 with respect to the imaging element holding member 31 with high accuracy.

[0061] Next, the differences between the first bonding portion 51 and the second bonding portion 52 will be described. The first bonding portion 51 adheres the imaging element 11 to the imaging element holding member 31 over a wide range so as to cover the back surface portion 11b of the imaging element 11 and the inner peripheral portion 31g of the imaging element holding member 31. Therefore, when an adhesive with a low viscosity is used for the first adhesive, there is a possibility that the application of the first adhesive to the back surface portion 11b may cause the coverage of the inner peripheral portion 31g to become shallow. Therefore, it is desirable to adopt an adhesive with a high viscosity for the first bonding portion 51 so as to cover both the back surface portion 11b and the inner peripheral portion 31g.

[0062] 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, a gap X1 needs to be provided between the movable portion 20b and the fixed portion 20a in order to secure the movable region of the movable portion 20b. Further, in order to hold the image sensor 11 on the side surface portion, it is necessary to provide a space for applying the second adhesive and a width X2 corresponding to the thickness of the side wall portion 31h of the image sensor holding member 31 inside thereof. In order to reduce the size of the first blur correction unit 20, it is desirable to reduce the width X2. Considering pouring the adhesive into such a narrow region, it is desirable to adopt an adhesive having a low viscosity for the second adhesive.

[0063] Thus, it is desirable to use an adhesive having a lower viscosity than the first adhesive for the second adhesive. Further, since the first adhesive is applied over a wider range 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 sub-adhesive portion.

[0064] In addition, since the imaging device 10 is assumed to be used in various temperature environments, it is desirable to obtain high shock resistance even in various temperature environments. Here, considering that the adhesive strength of the adhesive has a temperature dependence, it is desirable to combine adhesives having different temperature characteristics of adhesive strength for the first adhesive portion 51 and the second adhesive portion 52.

[0065] FIG. 13 is a diagram for explaining a selection example of the first adhesive portion 51 and the second adhesive portion 52 in consideration of the temperature characteristics of the adhesive strength. In FIG. 13, the temperature T is taken on the horizontal axis and the adhesive strength P is taken on the vertical axis, and the curve P 51 shows the temperature-adhesive strength characteristics of the first adhesive portion 51, and the curve P 52 shows the temperature-adhesive strength characteristics of the second adhesive portion 52. Further, the solid line P 51 +P 52 is the sum of the curve P 51 and the curve P 52 , that is, shows the temperature characteristics of the overall adhesive strength of the image sensor 11 with respect to the image sensor holding member 31.

[0066] As shown in Fig. 13, by combining a strong first adhesive portion 51 on the high-temperature side and a strong second adhesive portion 52 on the low-temperature side, it becomes possible to realize a holding mechanism for the imaging device 11 with high impact resistance in a wide temperature range. When the imaging device 10 is in use, since the temperature in the vicinity of the imaging device 11 tends to rise due to the influence of heat generation of the imaging device 11, etc., it is desirable to employ an adhesive that exhibits high adhesive strength on the high-temperature side for the first adhesive portion 51 which is the main adhesive portion.

[0067] As described above, the present invention has been described in detail based on its preferred embodiments. However, the present invention is not limited to these specific embodiments, and various forms within the scope without departing from the gist of this invention are also included in the present invention. Furthermore, each of the above-described embodiments merely shows one embodiment of the present invention, and it is also possible to appropriately combine each embodiment.

[0068] For example, regarding the magnet and the coil that constitute the VCM which is an actuator, it suffices that either one is arranged on the fixed portion and the other is arranged on the movable portion. Also, regarding the thrust magnet and the rear yoke that constitute the biasing portion, it suffices that either one is arranged on the fixed portion and the other is arranged on the movable portion.

[0069] Also, when the connecting member is arranged to extend in the vertical direction, the first adhesive portion may be arranged on the left side and the right side, and the second adhesive may be arranged on the upper side and the lower side. Further, when an opening is formed by forming three sides when the imaging device holding member is viewed from the optical axis direction and attaching the connecting member to the remaining one side, 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.

Explanation of Reference Numerals

[0070] 10 Imaging device 11 Imaging element 11b Rear surface portion 14 Camera control unit 15a First shake correction control unit 20 First shake correction unit 20a Fixed portion 20b Movable part 22 Rear yoke 22a First regulating part 23a First rear magnet group 26a First front magnet 31 Image sensor holding member 33a First coil 34 Actuator 36 Ball 38 Connecting member 39 Thrust magnet 51 First bonding part 52 Second bonding part 60 Second blur correction unit

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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 drive device according to claim 1, wherein the control means controls the drive of the movable part by controlling a current flowing through the coil based on the shake information and the position information.

6. 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.

7. 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.

8. 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;

9. An imaging apparatus comprising the image blur correction device according to claim 7 or 8.

10. A lens barrel comprising the image blur correction device according to claim 8.

11. 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. 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. 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. 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. 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. 16. The imaging device according to claim 13, wherein the first adhesive portion and the second adhesive portion have different characteristics.

17. 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. 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. 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. 20. The imaging device according to claim 19, wherein the viscosity of the second adhesive is lower than the viscosity of the first adhesive.

Images