JP2010282222A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device that achieves smooth lens drive even in case where a lens is used so as to move in a vertical direction. <P>SOLUTION: The lens driving device includes a lens holder having an opening for accommodating the lens and a support portion for supporting the lens holder so that the lens holder is displaced in the direction of the optical axis of the lens. The lens holder has first parallel counter faces and second parallel counter faces perpendicular to the first counter faces in its outer circumference. On at least one of the first counter surfaces and at least one of the second counter surfaces, a flat plate-like magnet which has a magnetic pole on a plate surface is attached respectively. A coil is disposed on the support portion so as to cause a current to flow in a direction parallel to the plate surface of the magnet and perpendicular to the optical axis of the lens. In addition, a magnetic member is disposed on the support member so as to counter the plate surface of the magnet with the coil between them. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens driving device, and is particularly suitable for use in an autofocus lens driving device mounted on a small camera or the like.

  In general, as a lens driving device, a motor-driven actuator using a stepping motor, a piezoelectric type actuator using distortion when an electric field is applied to a crystal body, and a voice coil used in a speaker or the like. There are known electromagnetically driven actuators and the like.

  For example, Patent Document 1 below discloses a voice coil type lens driving device that can be mounted for autofocus driving of a camera lens.

  In this lens driving device, a coil is mounted on the holder side that holds the lens, a magnet is mounted on the base side, and the holder is driven in the lens optical axis direction by an electromagnetic driving force generated by applying a current to the coil. I am doing so. Further, here, the holder is supported by a spring member, and the spring member is shared for power supply to the coil so that the wiring is not drawn out from the holder.

  According to this configuration, since the wiring for supplying power to the coil is not pulled out from the holder, it is possible to suppress a problem that the wiring is damaged due to unnecessary vibration or tension applied to the wiring during lens driving. On the other hand, in this configuration, the structure of the spring is complicated, so that there is a problem that the yield at the time of manufacturing the actuator is likely to decrease.

As a configuration for solving such a problem, a configuration in which a magnet is mounted on the holder side and a coil is mounted on the base side can be employed. In this case, since it is not necessary to wire the holder, it is not necessary to consider damage to the wiring when driving the lens, and the configuration can be simplified.
JP 2004-280031 A

  However, in this configuration, since the magnet is heavier than the coil, especially when moving the holder in the vertical direction, there is a difference between the downward movement and the upward movement due to the influence of gravity (speed of movement and drive response). Etc.) (this difference is hereinafter referred to as “driving difference”). For this reason, in this structure, when moving a holder to a perpendicular direction, there exists a possibility that smooth lens drive may not be performed.

  The present invention solves such problems, and provides a lens driving device that can smoothly drive the lens even when the lens driving device is used by moving the holder in the vertical direction. With the goal.

  In view of the above problems, the present invention has the following features.

  A lens driving device according to a first aspect of the present invention includes a holder that holds a lens, a support portion that supports the holder so as to be displaceable in the optical axis direction of the lens, and a side surface of the holder that is symmetrical to the optical axis. And a coil disposed on the support portion so as to face the magnet, and a magnetic member disposed on the support portion so as to face the magnet.

  The lens driving device according to a second aspect of the present invention is the lens driving device according to the first aspect, wherein the support portion regulates the movement of the holder in a direction perpendicular to the optical axis. A guide portion is provided for guiding the holder so as to be displaceable in the direction of the optical axis, and the magnetic member is arranged so that the magnetic force generated in the in-plane direction perpendicular to the optical axis is unbalanced. To do.

  A lens driving device according to a third aspect of the present invention is the lens driving device according to the first aspect, wherein the magnetic member is arranged so that magnetic forces generated in an in-plane direction perpendicular to the optical axis are balanced. It is characterized by.

  A lens driving device according to a fourth aspect of the present invention is the lens driving device according to the second or third aspect, wherein the magnetic member is divided into a plurality and the current input / output unit of the coil is electrically connected. The electrode is commonly used as an electrode connected to the electrode.

  The lens driving device according to a fifth aspect of the present invention is the lens driving device according to any one of the first to fourth aspects, wherein the magnetic member is composed of a plurality of magnetic bodies, It is arranged on the support so as to face the magnet.

  The lens driving device according to a sixth aspect of the present invention is the lens driving device according to any one of the first to fifth aspects, wherein the magnet is divided into a plurality of portions around the optical axis. And

  According to the lens driving device of the first aspect of the present invention, the holder is pulled in the in-plane direction perpendicular to the lens optical axis by the magnetic force acting between the magnet and the magnetic member, and is suspended by this attractive force. It will be in such a state. For this reason, even when the holder is moved in the vertical direction, it is not easily affected by gravity, and the drive difference between the upward drive and the downward drive is reduced. Therefore, even when the lens driving device is used in a state where the holder is moved in the vertical direction, the lens can be driven smoothly.

  In addition, since the magnet is arranged symmetrically with respect to the optical axis and the holder is driven by the electromagnetic driving force generated between the magnet and the coil, the driving force is applied only to one side of the holder. The moment does not act on. Therefore, lens driving can be performed more smoothly and driving torque can be reduced.

  In particular, in the lens driving device according to the first aspect of the present invention, if the configuration according to the second aspect is adopted, the magnetic force generated by the magnetic member in the in-plane direction perpendicular to the optical axis is unbalanced. As a result, the force acting on the holder is biased. Thereby, the lens holder moves along the guide portion while being pressed against the guide portion by the biased force. Therefore, lens driving without backlash can be realized.

  On the other hand, in the lens driving device according to the first aspect of the present invention, if the magnetic force acting between the magnetic member and the magnetic member is balanced as in the configuration according to the third aspect, the holder is biased in any direction. Since it will be in the state suspended stably, the movement of a holder can be stabilized more.

  Furthermore, if it is set as the structure which concerns on the said 4th aspect, since a magnetic member is shared as an electrode for supplying with electricity to a coil, the structure of a coil electric power feeding part can be simplified.

  Further, the magnetic force acting between the magnet and the magnetic member becomes the resistance of the driving force of the lens holder given by the power supply of the coil. However, if the configuration according to the fifth aspect is used, the size of the magnetic body is changed. Thus, the magnetic force can be easily adjusted so that the propulsive force is balanced.

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example when the present invention is implemented, and the present invention is not limited to what is described in the following embodiment.

  FIG. 1 is an exploded perspective view of a lens driving device according to an embodiment. 2A and 2B are diagrams showing the configuration of the lens holder, where FIG. 2A is a perspective view and FIG. 2B is a bottom view.

  Reference numeral 10 denotes a lens holder. The lens holder 10 has an octagonal shape in plan view. The lens holder 10 is formed with a circular opening 11 for accommodating the lens at the center position. The eight side surfaces of the lens holder 10 are arranged so as to be symmetric with respect to the optical axis of the lens mounted in the opening 11. Further, the lens holder 10 has a groove 12 and a hole 13 that engage with the shafts 60 and 61. Further, among the eight side surfaces of the lens holder 10, two opposing side surfaces and two side surfaces perpendicular to the two side surfaces are respectively mounted with magnets 20. The magnet 20 has N and S on one side. Has a two-pole arrangement structure in which is magnetized. Moreover, the size and magnetic strength of each magnet 20 are equal to each other.

  Reference numeral 30 denotes a base (corresponding to the support portion of the present invention). The base 30 is formed in a substantially square plate shape. The base 30 is formed with an opening 31 for guiding light transmitted through the lens to the image sensor, and further, two holes 32 for inserting the shafts 60 and 61 are formed. The base 30 is provided with four guide bodies 33 protruding around the opening 31. Convex portions 33 a are formed at the tip portions of the guide bodies 33. Note that the space surrounded by the four guide bodies 33 is the accommodation space S of the lens holder 10.

  A coil 40 is wound around the outer periphery of the four guide bodies 33. The coil 40 includes a first coil 41 and a second coil 42. The first coil 41 and the second coil 42 are connected in series and their winding directions are reversed. For this reason, the first coil 41 and the second coil 42 have opposite directions of current flow.

  Reference numeral 50 denotes a frame member (corresponding to the magnetic member of the present invention). The frame member 50 is formed by forming a plate made of a magnetic material into a substantially annular shape. The frame member 50 is attached to the base 30 and surrounds the outer periphery of the coil 40 (the outer periphery of the lens holder 10) over substantially the entire periphery. Note that the width and thickness of the frame member 50 are substantially equal in the entire region.

  Reference numerals 60 and 61 denote shafts (corresponding to guide portions of the present invention). Each of the shafts 60 and 61 has a circular cross section and a diameter slightly smaller than the inner diameters of the hole 12 and the groove 13 on the lens holder 10 side. The shafts 60 and 61 may be formed of either a magnetic material or a nonmagnetic material.

  Reference numeral 70 denotes a cover. The cover 70 is formed in a substantially rectangular plate shape like the base 30. The cover 70 is formed with an opening 71 for taking light into the lens. Further, the cover 70 is formed with two holes 72 into which the shafts 60 and 61 are inserted, and further, four long holes 73 into which the convex portions 33a of the guide body 33 are inserted.

At the time of assembly, the lens holder 10 is accommodated in the accommodation space S of the base from above. At this time, the groove 12 and the hole 13 of the lens holder 10 are aligned with the hole 32 of the base 30. In this state, the four magnets 20 face the coil 40 with a predetermined gap. Further, the four side surfaces of the lens holder 10 without the magnet 20 are close to the side surfaces of the guide body 33. Although not shown, a lens is mounted in advance on the opening 11 of the lens holder 10.

  Next, the shaft 60 is inserted from above the base 30 in the order of the groove 12 and the hole 32, and its lower end is fixed to the bottom surface of the base 30. Similarly, the shaft 61 is inserted from above the base 30 in the order of the hole 13 and the hole 32, and its lower end is fixed to the bottom surface of the base 30. Further, the frame member 50 is mounted on the base 30 from above.

  Finally, the cover 70 is attached to the base 30 from above so that the two holes 72 are inserted into the upper ends of the shafts 60 and 61 and the four long holes 73 are inserted into the convex portion 33a. Thereby, the lens holder 10 is attached to the base 30 and the cover 70 in a state in which the lens holder 10 can be displaced along the two shafts 60 and 61.

  FIG. 3A is a diagram illustrating a configuration of the lens driving device after assembling. FIG. 2B is a view showing a state in which the cover 70 is removed so that the internal state of the lens driving device shown in FIG.

  In the assembled state, the N pole of the magnet 20 faces the upper first coil 41, and the S pole of the magnet 20 faces the lower second coil 42. Therefore, when a driving current is applied to the first coil 41 and the second coil 42, an electromagnetic driving force acts on the magnet 20, and the lens holder 10 slides along the shafts 60 and 61.

  FIG. 4 is a diagram for explaining the driving operation of the lens driving device. FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG.

  FIG. 4A is a diagram showing a state when the lens holder 10 is at the home position. When in the home position, the lower end of the lens holder 10 is in contact with the base 30. As described above, the N and S magnetized regions of the magnet 20 face the first coil 41 and the second coil 42, respectively. Further, the first coil 41 and the second coil 42 have opposite directions of current flow.

  When a current in the direction shown in FIG. 5A flows through the first coil 41 and the second coil 42 from the home position, an upward driving force acts on the magnet 20, and the lens holder 10 As shown in FIG. 4B, the actuator is displaced upward from the home position along the shafts 60 and 61. Further, when a current flows in the opposite direction to the case of FIG. 10A from the state of FIG. 9B to the first coil 41 and the second coil 42, a downward driving force acts on the magnet 20. The lens holder 10 is displaced downward along the shafts 60 and 61. In the figure, a black dot mark indicates a direction toward the drawing reference person, and a cross mark indicates a direction away from the drawing reference person.

  In this way, the lens is positioned at the on-focus position while displacing the lens holder 10 upward and downward. At this time, the lens holder 10 receives attractive forces from two opposite directions and two directions orthogonal to the two magnetic forces generated between the four magnets 20 and the frame member 50, and is substantially uniform in the outer circumferential direction by these four attractive forces. It is in a state of being hung at the interval position. For this reason, even when the lens holder 10 is moved in the vertical direction, it is less susceptible to the influence of gravity, and a drive difference between the downward drive and the upward drive is less likely to occur. Even if the power supply to the coil 40 is interrupted after the lens is positioned at the on-focus position, the lens holder 10 is held at the on-focus position by this attractive force.

As described above, in this embodiment, even when the lens holder is moved in the vertical direction, the driving difference between the upward driving and the downward driving is reduced, so that the lens driving is performed in a state in which the lens holder is moved in the vertical direction. Even when the apparatus is used, the lens holder 10 can be driven smoothly.

  In the present embodiment, since the magnet 20 and the coil 40 are disposed on both sides of the lens holder 10, unlike the configuration in which the magnet and the coil are disposed on only one side of the lens holder 10, the lens holder 10 is driven. No moment acts on the lens holder 10. For this reason, while being able to drive the lens holder 10 smoothly, drive torque can be reduced.

  In the present embodiment, as described above, the sizes and magnetic strengths of the four magnets 20 are equal to each other. In this case, if the distance between the outer surface of the four magnets 20 and the inner surface of the frame member 50 are equal, the magnetic forces generated between the magnets 20 and the frame member 50 are equal to each other. It is balanced in the in-plane direction perpendicular to the optical axis of the lens. Thus, if the four magnetic forces are balanced, the lens holder 10 is stably suspended without being biased in any direction, and thus the movement of the lens holder 10 can be stabilized.

  FIG. 5 is a diagram illustrating a schematic configuration of a camera module when the lens driving device 100 according to the present embodiment is mounted on a camera.

  A filter 201 and an image sensor 202 are disposed on the base 30 side. The base 30 is provided with a hall element 80 as a position sensor, and the position of the lens holder 10 is detected based on a signal from the hall element 80.

During the focusing operation, a CPU (Central Processing Unit) 301 controls the driver 302 to displace the lens holder 10 in the lens optical axis direction from the home position in FIG. 4 to a predetermined position. At this time, a position detection signal from the hall element 80 is input to the CPU 301. At the same time, the CPU 301 processes a signal input from the image sensor 202 to acquire a contrast value of the captured image. Then, the position of the lens holder 10 having the best contrast value is acquired as the on-focus position.

  Thereafter, the CPU 301 drives the lens holder 10 toward the on-focus position. At that time, the CPU 301 monitors the signal from the hall element 80 and drives the lens holder 10 until the signal from the hall element 80 is in a state corresponding to the on-focus position. Thereby, the lens holder 10 is positioned at the on-focus position.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, Moreover, various changes besides the above are possible for embodiment of this invention.

  For example, various modifications can be made to the arrangement structure of the magnetic members as shown in FIGS.

  In the modification shown in FIG. 6, the frame member 50 is formed in a substantially U shape in plan view so as to surround the outside of the three magnets and not surround the outside of the remaining one magnet. In such a configuration, the magnetic force generated between the magnet 20 and the frame member 50 is unbalanced in the direction in which the frame member 50 exists only on one side, and the lens holder 10 is pulled in the direction of the arrow D1. As a result, the shafts 60 and 61 are pressed against the inner surface of the groove 12 and the hole 13 on the frame member 50 side, and when the lens holder 10 is driven, the groove 12 and the hole 13 are pressed against the shafts 60 and 61, respectively. 10 moves along the shaft 60. For this reason, the play at the time of driving the lens holder 10 is effectively suppressed, and a smooth driving operation can be realized.

  In this modified example, since the force for suspending the lens holder 10 is slightly reduced compared to the above embodiment, the effect of reducing the drive difference between the upward drive and the downward drive is slightly reduced. However, in this case as well, the effect of reducing the drive difference is exhibited. Therefore, the modified example shown in FIG. 6 is effective when it is desired to reduce both the play and the drive difference when the lens holder 10 is driven. .

  Further, although the magnetic force is made unbalanced by losing a part of the frame member 50 here, the configuration of making the magnetic force acting on the lens holder 10 unbalanced is the distance between each magnet 20 and the magnetic member 50. It is good also as a structure to which the magnitude | size (width | variety and thickness) of the part of the frame member 50 which opposes each magnet 20 is varied.

  In the modification shown in FIG. 7, the frame member 50 is divided into a first frame member 51 and a second frame member 52 so as to surround the magnet 20 two by two. A predetermined gap is provided between the first frame member 51 and the second frame member 52. Further, the first frame member 51 and the second frame member 52 are also used as electrodes when power is supplied to the coil 40. That is, one of the current input / output portions to the coil 40 is connected to the first frame member 51 and the other is connected to the second frame member 52. One of the wirings for applying a current from the driver 302 to the coil 40 is connected to the first frame member 51, and the other is connected to the second frame member 52. By adopting such a configuration, the configuration of the power feeding portion to the coil 40 can be simplified.

  In the modification shown in FIG. 8, the frame member 50 includes a main frame member 53 that surrounds the outer periphery of the coil 40 (the outer periphery of the lens holder 10), and four magnetic bodies 54 that are attached to the main frame member 53. ing. The main frame member 53 is made of a nonmagnetic material and is formed in a substantially annular shape. The magnetic body 54 is a rectangular plate made of a magnetic material, and is mounted inside the main frame member 53 so as to face the magnet 20.

  Since the magnetic force acting between the magnet 20 and the frame member 50 becomes the resistance of the driving force of the lens holder 10 given by the power supply of the coil 40, if the magnetic force is too large, the driving force of the lens holder 10 by the coil 40 is large. And must be. Therefore, if the magnetic body 54 is mounted on the main frame member 53 as described above, the magnetic force can be easily adjusted so that the propulsive force can be balanced by changing the size of the magnetic body 54. It can be performed.

  In this modification, the magnetic force generated between each magnet 20 and the magnetic body 54 can be made different by adjusting the material and size of the magnetic body 54, thereby acting on the lens holder 10. Magnetic force to be imbalanced. Thus, by making the magnetic force unbalanced, the lens holder 10 is moved while the groove 12 and the hole 13 are pressed against the shafts 60 and 61, respectively, when the lens holder 10 is driven, as in the modified example of FIG. be able to. Thereby, the play at the time of driving the lens holder 10 can be suppressed, and a smooth driving operation can be realized.

  Further, in the present embodiment, the guide portion at the time of movement of the lens holder 10 is configured by the shafts 60 and 61. However, the configuration is not limited thereto, and other configurations may be employed.

  FIG. 9 is a diagram illustrating another configuration example of the guide unit. As shown in FIG. 4A, on the four side surfaces of the lens holder 10 where the magnet 20 is not mounted, protrusions 14 having a triangular cross section extending in the vertical direction are formed. On the other hand, V-shaped grooves 33 b that engage with the protrusions 14 are respectively formed on the side surfaces of the guide body 33 facing these side surfaces.

As shown in FIG. 4B, when the lens holder 10 is mounted on the base 30, the protrusion 14 is fitted into the groove 33b. When the lens holder 10 moves up and down in this state, the protrusion 14 slides in the groove 33b. With such a configuration, the guide structure can be easily provided.

  Furthermore, in the present embodiment, magnets 20 are provided on the four side surfaces of the lens holder 10. However, the magnet 20 only needs to be arranged symmetrically with respect to the optical axis. For example, the magnet 20 may be arranged only on two opposing side surfaces, or on all side surfaces (entire circumferential surfaces) of the lens holder 10. May be. When the magnet 20 is disposed on all side surfaces of the lens holder 10, the divided magnets may be disposed in an annular shape, or may be a single annular magnet.

  Further, in the present embodiment, the magnet 20 may have a one-pole arrangement structure, and the coil 40 may be a single coil.

  In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

1 is an exploded perspective view showing a configuration of a lens driving device according to an embodiment. The figure which shows the structure of the lens holder which concerns on embodiment Assembly perspective view showing a configuration of a lens driving device according to an embodiment The figure which shows the drive state of the lens drive device which concerns on embodiment The figure which shows the structure of the camera module which concerns on embodiment The figure which shows the modification of the frame member which concerns on embodiment The figure which shows the modification of the frame member which concerns on embodiment The figure which shows the modification of the frame member which concerns on embodiment The figure which shows the other structural example of the guide part which concerns on embodiment

DESCRIPTION OF SYMBOLS 10 ... Lens holder 20 ... Magnet 30 ... Base 40 ... Coil 50 ... Frame member 60, 61 ... Shaft

Claims (4)

A lens driving device comprising: a lens holder having an opening for housing a lens; and a support unit that supports the lens holder so as to be displaceable in the optical axis direction of the lens,
The lens holder includes a first opposing surface parallel to each other and a second opposing surface perpendicular to the first opposing surface and parallel to each other on the outer periphery,
A plate-like magnet having a magnetic pole on a plate surface is attached to at least one surface of the first facing surface and at least one surface of the second facing surface, respectively.
The support portion is provided with a coil that can flow an electric current in a direction parallel to the plate surface of the magnet and perpendicular to the optical axis of the lens, and the plate surface of the magnet with the coil interposed therebetween. The lens drive device characterized by the above-mentioned.   The lens driving device according to claim 1, wherein a guide shaft that is engaged with a groove or a hole provided in the lens holder and guides the displacement of the lens holder is provided on the support portion. . The magnet has a north pole and a south pole on a plate surface facing the magnetic member with the coil interposed therebetween,
3. The coil according to claim 1, wherein currents that are opposite to each other can flow simultaneously to a portion that receives a magnetic field generated from the N pole and a portion that receives a magnetic field generated from the S pole. Lens drive device. 4. The lens driving device according to claim 1, wherein an area of a region where the magnet and the magnetic member face each other does not change with the displacement of the lens holder.

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