JP2006323295A - Lens-driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens-driving device which will not cause friction loss, when driving a movable lens and which is miniaturized. <P>SOLUTION: The lens-driving device 1 has the movable lens 2; a first magnet 3 arranged around the movable lens 2 and integrally displaced with the movable lens 2; second magnets 4a to 4d arranged facing the first magnet 3 and holding the movable lens 2, in a floating state by magnetic force generated between the first magnet 3 and the second magnets 4a to 4d; and electromagnets 5a to 5d arranged facing the first magnet 3 and displacing the movable lens 2 by magnetic force generated between the fist magnet 3 and the electromagnets 5a to 5d. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device mounted on an optical apparatus such as an imaging device.

A lens driving device mounted on an imaging device or the like employs a configuration in which the movable lens is displaced by a driving device such as a stepping motor while the movable lens is mechanically held (see, for example, Patent Document 1).
JP-A-7-151947

  However, in the conventional lens driving device, it is necessary to mechanically hold the movable lens so as to be displaceable, and since such a mechanism is complicated, there is a problem that the lens driving device becomes large. In addition, when the movable lens is mechanically held, the moving direction and the moving range are restricted. Therefore, when the lens is driven in various directions, the above problem becomes more prominent. Furthermore, the conventional lens driving device has a problem that it is unavoidable that friction loss occurs when the movable lens is driven.

  In view of the above problems, an object of the present invention is to provide a lens driving device that does not generate friction loss when driving a movable lens and can be reduced in size.

  In order to solve the above problems, in the lens driving device according to the present invention, a movable lens, a first magnet disposed around the movable lens and displaceable integrally with the movable lens, and the first magnet A second magnet for holding the movable lens in a floating state by a magnetic force generated between the first magnet and the first magnet; And an electromagnet that displaces the movable lens by a magnetic force generated between the two.

  In the lens driving device according to the present invention, since the movable lens is held in a floating state by the magnetic force acting between the first magnet and the second magnet, if the electromagnet is energized in this state, the first magnet The movable lens is displaced by the magnetic force generated between the magnet and the electromagnet. Therefore, even when the movable lens is driven along the optical axis by controlling excitation, the movable lens can be displaced even when the movable lens is tilted or when the movable lens is driven in a direction perpendicular to the optical axis. There is no need to keep it. Therefore, it is possible to reduce the size of the lens driving device. Further, since the movable lens is in a state of being levitated by magnetic force, no friction loss occurs when the movable lens is driven.

  In the present invention, the first magnet is a permanent magnet having different magnetic poles on the inner peripheral side and the outer peripheral side, and the second magnet is the outer peripheral side of the first magnet and both sides in the optical axis direction. A permanent magnet having a concave surface facing the three sides of the first magnet, the same polarity as the outer peripheral side of the first magnet is formed on the side facing the outer peripheral side of the first magnet, and between the first magnet It is preferable to hold the movable lens in a floating state by a magnetic repulsive force generated in

  In the present invention, it is preferable that a plurality of the second magnets and the electromagnets are arranged around the movable lens. If comprised in this way, a movable lens can be hold | maintained with the stable attitude | position, and it can drive in a stable state.

  In the present invention, it is preferable that the second magnets and the electromagnets are arranged point-symmetrically or at equiangular intervals with respect to the optical axis center of the movable lens. If comprised in this way, a movable lens can be hold | maintained with the more stable attitude | position, and it can drive in a more stable state.

  In the present invention, the plurality of electromagnets include an electromagnet that simultaneously applies an attractive force toward one side in the optical axis direction and a repulsive force toward the other side to the first magnet when energized. can do. With this configuration, the electromagnet can apply a force in the optical axis direction to the movable lens, so that the position of the movable lens in the optical axis direction and the tilt of the movable lens can be adjusted by controlling excitation. Can do.

  In the present invention, the plurality of electromagnets include a configuration in which an electromagnet that causes one of magnetic force of repulsive force and repulsive force in a direction orthogonal to the optical axis direction to act on the first magnet when energized. Can be adopted. If comprised in this way, a movable lens can be driven in the direction orthogonal to an optical axis.

  In the present invention, the plurality of electromagnets include an electromagnet provided with a yoke at a position shifted from the center of the first magnet in the optical axis direction to one side or the other side in the optical axis direction. Preferably it is. With this configuration, an attractive force directed to one side or the other side in the optical axis direction acts between the yoke and the first magnet in a state where energization to the electromagnet is stopped. It can be held stably.

  In the present invention, for example, the movable lens may be held inside a cylindrical lens holder, and in this case, the first magnet is attached to the outer peripheral surface of the lens holder. In addition, a first magnet may be attached to the outer peripheral side of the movable lens inside the lens holder.

  In the lens driving device of this embodiment, since the movable lens is levitated by magnetism, no friction loss occurs when the movable lens is driven. Therefore, since the movable lens can be operated smoothly with good reproducibility, focusing and zooming of the movable lens can be performed reliably and smoothly. In addition, camera shake or the like of the imaging apparatus can be reliably and smoothly prevented. Moreover, since friction does not occur, it is possible to prevent the generation of dust that contributes to wear of members due to friction, dirt on the lens and image sensor, and the generation of frictional noise, etc., so that clear recording can be performed. Do not disturb. Furthermore, since there is no need to mechanically hold the movable lens, the number of parts can be reduced, and the structure can be simplified even when the movable lens is driven in various directions. Therefore, it is possible to reduce the size and cost of the lens driving device. In addition, the power required for driving can be reduced and the operation speed can be improved.

  A lens driving device to which the present invention is applied will be described with reference to the drawings.

[Embodiment 1]
(overall structure)
FIGS. 1A and 1B are a plan view and a cross-sectional view taken along line AA ′ schematically showing a configuration of a main part of the lens driving device according to Embodiment 1 of the present invention.

  As shown in FIGS. 1A and 1B, a lens driving device 1 according to this embodiment includes a movable lens 2 and an annular first attached to the movable lens 2 and displaceable integrally with the movable lens 2. Magnet 4, four second magnets 4 a to 4 d that face the first magnet 3 on the outside, and four electromagnets 5 a to 5 d that face the first magnet 3 on the outside. ing.

  The first magnet 3 is composed of a permanent magnet having different magnetic poles directed to the inner peripheral side and the outer peripheral side. In this embodiment, the inner peripheral side is magnetized to the S pole and the outer peripheral side is magnetized to the N pole. In the first magnet 3, the outer peripheral surface is constituted by an arc surface with the center extending in the optical axis direction L and has a structure in which magnetic force concentrates at the center.

  The second magnets 4 a to 4 d are permanent magnets arranged at equiangular intervals around the movable lens 2, and hold the movable lens 2 in a floating state by a magnetic force generated between the second magnets 4 a to 4 d and the first magnet 3. It has a function. That is, each of the second magnets 4a to 4d is magnetized to a pole having a different end from the end opposite to the first magnet 3, and in this embodiment, the magnetization direction of the first magnet 3 is Corresponding to the first magnet 3, the end facing the first magnet 3 is magnetized to the N pole, and the opposite end is magnetized to the S pole.

  In the second magnets 4 a to 4 d, the end portion facing the first magnet 3 is provided with a concave surface 41 facing the outer circumference side of the first magnet 3 and the three sides on both sides in the optical axis direction L. For this reason, in the second permanent magnets 4a to 4d, the magnetization of the central portion of the concave surface 41 is weak and the magnetization of both end portions is strong. Therefore, the movable lens 2 magnetically levitates more stably near the central portion of the concave surface. It will be.

  The electromagnets 5a to 5b are arranged at equiangular intervals around the movable lens 2, and the electromagnets 5a to 5b and the second magnets 4a to 4d are alternately arranged. The electromagnets 5a to 5b are configured by a U-shaped yoke 51 having an opening facing the first magnet 3 and a coil 52 wound around one of the arm portions 511 and 512 of the yoke 51. Each coil of the four electromagnets 5a to 5b is configured to be supplied with a predetermined current from a control circuit (not shown). Here, the tip ends of the arm portions 511 and 512 of the yoke 51 are positioned so as to sandwich the first magnet 3 from both sides in the optical axis direction L.

(Operation)
In the lens driving device 1 of the present embodiment, in a state where no current is supplied to any of the four electromagnets 5a to 5d, the movable lens is generated by the magnetic repulsive force generated between the first magnet 3 and the second magnets 4a to 4d. 2 is kept floating at the origin position.

  From this state, for example, when the movable lens 2 is driven to one side of the optical axis direction L (direction indicated by the arrow L1), the control circuit is on the side indicated by the arrow L1 in any of the four electromagnets 5a to 5d. The coil 52 is energized so that the tip of the arm portion 511 of the yoke 51 located is the S pole and the tip of the arm 512 located on the opposite side (the side indicated by the arrow L2) is the N pole. As a result, in any of the four electromagnets 5a to 5d, the distal end portion of the arm portion 511 generates an attractive force toward the one side in the optical axis direction L with respect to the first magnet 3, and the distal end portion of the arm portion 512. Generates a repulsive force toward the one side in the optical axis direction L with respect to the first magnet 3. Therefore, the movable lens 2 moves to one side of the optical axis direction L (the direction indicated by the arrow L1) while being magnetically levitated.

  Contrary to the above operation, in any of the four electromagnets 5a to 5d, the tip of the arm portion 511 of the yoke 41 located on the side indicated by the arrow L1 is the N pole, and the control circuit has the opposite side (arrow L2 When the coil 52 is energized so that the tip of the arm 512 located on the side indicated by S is the S pole, the tip of the arm 511 is the first magnet 3 in any of the four electromagnets 5a to 5d. , A repulsive force directed to the other side in the optical axis direction L (the direction indicated by the arrow L2) is generated, and the distal end portion of the arm portion 512 generates an attractive force directed to the other side in the optical axis direction L with respect to the first magnet 3. generate. Therefore, the movable lens 2 moves to the other side of the optical axis direction L (direction indicated by the arrow L2) while magnetically floating.

  Further, in the control circuit, among the four electromagnets 5a to 5d, in the adjacent two electromagnets 5a and 5b, the tip of the arm portion 511 of the yoke 51 located on the side indicated by the arrow L1 becomes the S pole, and vice versa. The coil 52 of the electromagnets 5a and 5b is energized so that the tip of the arm portion 512 located on the side (the side indicated by the arrow L2) is an N pole, and the other two electromagnets 5c and 5d are indicated by the arrow L1. Of the electromagnets 5c and 5d so that the tip of the arm 511 of the yoke 51 located on the side becomes the N pole and the tip of the arm 512 located on the opposite side (the side indicated by the arrow L2) becomes the S pole. When the coil 52 is energized, the electromagnets 5a and 5b generate a magnetic force toward the one side in the optical axis direction L (direction indicated by the arrow L1) with respect to the first magnet 3, and the electromagnets 5c and 5d The other side of the optical axis direction L with respect to the magnet 3 (arrow L2 Generating a magnetic force toward the direction) indicated. Therefore, the movable lens 2 is tilted while being magnetically levitated.

  Furthermore, when the control circuit supplies the four electromagnets 5a to 5d with a current apportioned at a predetermined ratio to each coil 52, the movable lens 2 can be tilted in an arbitrary direction. Further, the tilt driving of the movable lens 2 and the movement in the optical axis direction L can be simultaneously performed.

(Main effects of this form)
As described above, in the lens driving device 1 of the present embodiment, the movable lens 2 is levitated by magnetism, so that no friction loss occurs when the movable lens 2 is driven. Therefore, since the movable lens 2 can be operated smoothly with good reproducibility, focusing and tilt adjustment of the movable lens 2 can be performed reliably and smoothly. In addition, camera shake or the like of the imaging apparatus can be reliably and smoothly prevented. Moreover, in the lens driving device 1 of the present embodiment, since friction does not occur when the movable lens 2 is driven, it is possible to prevent the generation of dust that contributes to wear of the member due to friction and dirt on the lens and the image sensor, and Since the generation of frictional noises can be prevented, clear recording can be performed. Furthermore, since it is not necessary to hold the movable lens 2 mechanically, the number of parts can be reduced, and the structure can be simplified even when the movable lens 2 is driven in various directions. Therefore, the lens driving device 1 can be reduced in size and cost. In addition, the power required for driving can be reduced and the operation speed can be improved.

  In this embodiment, a plurality of second magnets 4 a to 4 d and electromagnets 5 a to 5 d are arranged around the movable lens 2. In addition, the second magnets 4a to 4d and the electromagnets 5a to 5d are respectively arranged symmetrically with respect to the center of the optical axis of the movable lens 2 and at equal angular intervals. For this reason, the movable lens 2 can be held in a more stable posture and can be driven in a more stable state.

[Embodiment 2]
2A, 2B, and 2C are a plan view, a cross-sectional view taken along line BB ', and a cross-sectional view schematically showing a configuration of a main part of the lens driving device according to Embodiment 2 of the present invention. It is C 'sectional drawing. Since the basic configuration of this embodiment is the same as that of Embodiment 1, common parts are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIGS. 2A, 2B, and 2C, the lens driving device 1 of the present embodiment is mounted around the movable lens 2 and can be displaced integrally with the movable lens 2. An annular first magnet 3, four second magnets 4 a to 4 d facing outward with respect to the first magnet 3, and eight electromagnets 5 a to 5 h facing outward with respect to the first magnet 3. And have.

  As in the first embodiment, the first magnet 3 is composed of a permanent magnet whose inner peripheral side is magnetized to the S pole and whose outer peripheral side is magnetized to the N pole. In the first magnet 3, the outer peripheral surface is formed by an arc surface projecting from the center in the optical axis direction L and has a structure in which magnetization is concentrated at the center.

  The second magnets 4a to 4d are permanent magnets for holding the movable lens 2 in a state of being levitated by the magnetic force generated between the first magnet 3 and, in this embodiment, the first magnet 3 is attached. Corresponding to the magnetic direction, the end facing the first magnet 3 is magnetized to the N pole, and the opposite end is magnetized to the S pole. In the second magnets 4 a to 4 d, the end portion facing the first magnet 3 is provided with a concave surface 41 facing the outer circumference side of the first magnet 3 and the three sides on both sides in the optical axis direction L.

  Of the eight electromagnets 5a to 5h, the four electromagnets 5a to 5d are arranged at equiangular intervals around the movable lens 2 as in the first embodiment, and the electromagnets 5a to 5b and the second magnets 4a to 4d Are arranged alternately. The electromagnets 5a to 5b are configured by a U-shaped yoke 51 having an opening facing the first magnet 3 and a coil 52 wound around one of the arm portions 511 and 512 of the yoke 51. Each coil 52 of the four electromagnets 5a to 5b is configured to be supplied with a predetermined current from a control circuit (not shown).

  Here, in the four electromagnets 5a to 5d, the yoke 51 is disposed at a position shifted by the dimension G from the center of the first magnet 3 in the optical axis direction to one side in the optical axis direction (direction indicated by the arrow L1). Yes. For this reason, the distance between the arm portion 512 of the yoke 51 and the first magnet 3 is shorter than the distance between the arm portion 511 of the yoke 51 and the first magnet 3. Accordingly, the attractive force acting between the arm portion 512 of the yoke 51 and the first magnet 3 in a state where the energization to the coil 52 is stopped is between the arm portion 511 of the yoke 51 and the first magnet 3. Since it is larger than the acting attractive force, a force directed to the other side of the first magnet 3 in the optical axis direction (the direction indicated by the arrow L2) is acting.

  In this embodiment, the remaining four electromagnets 5e to 5h are arranged at equiangular intervals around the movable lens 2, and the electromagnets 5a to 5b, the electromagnets 5e to 5h, and the second magnets 4a to 4d are alternately arranged. Yes.

  Here, the electromagnets 5e to 5h are composed of a plate-like yoke 55 having one end facing the first magnet 3 and a coil 56 wound around the yoke 55, and each coil of the electromagnets 5e to 5h. 56 are also configured so that a predetermined current is supplied from a control circuit (not shown).

  Also in the lens driving device 1 configured as described above, a magnetic repulsive force generated between the first magnet 3 and the second magnets 4a to 4d in a state where any of the eight electromagnets 5a to 5h is not energized. Thus, the movable lens 2 is held in a state where it floats at the origin position.

  From this state, the operation when the movable lens 2 is driven in the optical axis direction L and the operation when the movable lens 2 is tilted are the same as those in the first embodiment, and thus the description thereof is omitted. When a predetermined current is supplied from the control circuit (not shown) to the electromagnets 5e to 5h, the movable lens 2 can be driven in a direction orthogonal to the optical axis direction L (direction indicated by an arrow L3).

  For example, in the two adjacent electromagnets 5e and 5f among the four electromagnets 5e to 5h, for example, the end of the yoke 55 that is close to the first magnet 3 is located on the opposite side of the S pole. The coil 56 of the electromagnets 5e and 5f is energized so that the end portion to be the N pole, and in the other two electromagnets 5g and 5h, the end portion closer to the first magnet 3 of the yoke 55 is the N pole, When the coil 56 of the electromagnets 5e and 5f is energized so that the end located on the opposite side is the S pole, the electromagnets 5a and 5b are perpendicular to the optical axis direction L with respect to the first magnet 3. The electromagnets 5g and 5h generate a repulsive force in a direction orthogonal to the optical axis direction L with respect to the first magnet 3. Therefore, the movable lens 2 moves in a direction perpendicular to the optical axis direction L while being magnetically levitated.

  Here, when the control circuit supplies a current apportioned at a predetermined ratio to the coils 52 of the four electromagnets 5e to 5h, the movable lens 2 in an arbitrary direction orthogonal to the optical axis direction L. Can be moved. Such driving of the movable lens 2 can be performed simultaneously with movement in the optical axis direction L and tilt driving.

  As described above, in the lens driving device 1 according to the present embodiment, in addition to the operation described in the first embodiment, the movable lens 2 can be driven in a direction orthogonal to the optical axis direction L. Since 2 is levitated by magnetism, the same effects as those of the first embodiment are obtained, such as no friction loss occurs when the movable lens 2 is driven.

  In the present embodiment, a plurality of second magnets 4 a to 4 d, electromagnets 5 a to 5 d, and electromagnets 5 e to 5 h are arranged around the movable lens 2. In addition, the second magnets 4 a to 4 d, the electromagnets 5 a to 5 d, and the electromagnets 5 e to 5 h are respectively arranged symmetrically with respect to the optical axis center of the movable lens 2 and at equal angular intervals. For this reason, the movable lens 2 can be held in a more stable posture and can be driven in a more stable state.

  Further, in this embodiment, in the four electromagnets 5a to 5d, the yoke 51 is disposed at a position shifted from the center of the first magnet 3 in the optical axis direction to one side in the optical axis direction (direction indicated by the arrow L1). In a state where energization of the coil 52 is stopped, a force directed toward the other side of the first magnet 3 in the optical axis direction (direction indicated by the arrow L2) is acting. Therefore, the movable lens 2 can be stably held at the origin position.

  Note that the configuration in which the movable lens 2 is stably held at the origin position by the attractive force acting between the yoke 52 and the first magnet 3 in a state where the energization to the coil 52 is stopped is the four electromagnets 5a to 5d. This can be realized even when the yoke 51 is disposed at a position shifted from the center of the first magnet 3 in the optical axis direction to the other side in the optical axis direction (direction indicated by the arrow L2). In addition, in the electromagnets 5e to 5h, or in both the electromagnets 5a to 5d and the electromagnets 5e to 5h, the yokes 52 and 55 are connected to the first and second coils in a state where energization to the coil 52 is stopped. The movable lens 2 may be stably held at the origin position by the attractive force acting between the magnet 3.

[Embodiment 3]
FIGS. 3A, 3B, and 3C are cross-sectional views schematically showing a configuration of a main part of a lens driving device according to another embodiment of the present invention.

  In the first and second embodiments, the first magnet 3 is directly attached to the movable lens 2, but the movable lens 2 is held by the cylindrical lens holder 7 as shown in FIG. In addition, a configuration in which the first magnet 3 is attached to the outer peripheral surface of the lens holder 7 may be employed. In this case, as in the first and second embodiments, the second magnet 4 and the electromagnet 5 are arranged outside the lens holder 7. FIG. 3A shows a configuration in which two movable lenses 2 are held on the lens holder 7. With this configuration, the two movable lenses 2 can be driven simultaneously. it can.

  Further, as shown in FIG. 3B, the first magnet 3 is directly attached to the movable lens 2 as in the first and second embodiments, while the other lens 8 is held around the first magnet 3. A configuration may be adopted in which a cylindrical lens holding body 7 is disposed, and the second magnet 4 and the electromagnet 5 are held inside the lens holding body 7. With this configuration, when the lens 8 held by the lens holder 7 is driven in the optical axis direction L by another driving device, the movable lens 3 can be simultaneously driven in the optical axis direction L, and the electromagnet 5 can be moved. The movable lens 3 can also be driven independently of the lens 8 by the power supply.

  Further, as shown in FIG. 3C, as in the first and second embodiments, the first magnet 3 is directly attached to the movable lens 2, and the second magnet 4 and the electromagnet 5 are provided outside thereof. When arranged, a cylindrical lens holding body 7 holding another lens 8 may be arranged on one side of the movable lens 3 in the optical axis direction. If comprised in this way, while the lens 8 hold | maintained at the lens holding body 7 can be driven to the optical axis direction L with another drive device, the movable lens 3 is made independent of the lens 8 by the electric power feeding to the electromagnet 5. It can also be driven.

  In addition, in the said form, although the 2nd magnet 4 was comprised with the permanent magnet, you may comprise with an electromagnet. In the above embodiment, an annular permanent magnet is used as the first magnet 3. However, a plurality of permanent magnets may be arranged around the movable lens 2 and used as the first magnet 3. Further, in the above-described embodiment, four second magnets 4 and four or eight electromagnets 5 are shown. However, the number is not limited, and an optimum number is selected according to the size of the movable lens 2 and the like. A magnet may be used.

(A), (b) is the top view and AA 'sectional drawing which show typically the structure of the principal part of the lens drive device which concerns on Embodiment 1 of this invention. (A), (b), (c) is the top view which shows typically the structure of the principal part of the lens drive device which concerns on Embodiment 2 of this invention, BB 'sectional drawing, and CC' It is sectional drawing. (A), (b), (c) is sectional drawing which shows typically the structure of the principal part of the lens drive device which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Movable lens 3 1st magnet 4, 4a-4d 2nd magnet 5, 5a-5h Electromagnet

Claims (8)

  Magnetic force generated between a movable lens, a first magnet disposed around the movable lens and displaceable integrally with the movable lens, and the first magnet disposed opposite to the first magnet. A second magnet that holds the movable lens in a levitated state, and an electromagnet that is disposed opposite to the first magnet and displaces the movable lens by a magnetic force generated between the first magnet and the second magnet. A lens driving device. The first magnet according to claim 1, wherein the first magnet is a permanent magnet having different magnetic poles on the inner peripheral side and the outer peripheral side,
The second magnet is a permanent magnet having a concave surface facing the outer peripheral side of the first magnet and three sides on both sides in the optical axis direction, and the second magnet is arranged on the side facing the outer peripheral side of the first magnet. A lens driving device, wherein the movable lens is held in a floating state by a magnetic repulsive force generated between the first magnet and the same pole as the outer periphery of the first magnet.   3. The lens driving device according to claim 1, wherein a plurality of the second magnets and the electromagnets are arranged around the movable lens.   4. The lens driving device according to claim 3, wherein the second magnets and the electromagnets are arranged point-symmetrically or at equiangular intervals with respect to the optical axis center of the movable lens.   5. The electromagnet according to claim 3, wherein the plurality of electromagnets simultaneously cause an attractive force directed to one side in the optical axis direction and a repulsive force directed to the other side to the first magnet when energized. A lens driving device.   The electromagnet according to any one of claims 3 to 5, wherein the plurality of electromagnets, when energized, cause one of a magnetic force of attraction and repulsion in a direction orthogonal to the optical axis direction to act on the first magnet. A lens driving device characterized by being included.   7. The yoke according to claim 3, wherein the plurality of electromagnets are provided with yokes at positions shifted from the center of the first magnet in the optical axis direction to one of the one side and the other side in the optical axis direction. A lens driving device including an electromagnet. In any one of Claim 1 thru | or 7, The said movable lens is hold | maintained inside a cylindrical lens holding body,
A lens driving device, wherein the first magnet is attached to an outer peripheral surface of the lens holder.

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