JP2015011301A - Lens driving device and camera unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device which allows reduction in weight of a driven part driven by a second driving member for shake correction, can have improved impact resistance, allows reduction in power consumption of the second driving member, and can be entirely miniaturized, and to provide a camera unit.SOLUTION: A lens driving device 10 includes; a fixed base 2; a lens holding member 3 holding a lens; a movable base 4 which holds the lens holding member 3 movably in an optical axis direction and is supported on the fixed base 2 movably in a direction orthogonal to the optical axis direction; a first actuator 5 as a first driving member which drives the lens holding member 3 in the optical axis direction; and a second actuator 6 as a second driving member which drives the movable base 4 in the orthogonal direction with a coil 62 and a magnet 61. The first actuator 5 is held on the fixed base 2.

Description

  The present invention relates to a lens driving device and a camera unit that can be mounted on a mobile phone or the like.

  In recent years, with the spread of smartphones, there has been an increasing demand for advanced camera functions, smaller cameras, and lower profiles. Among them, shooting scenes on mobile phones are often shot with one hand compared to digital cameras, etc., and there are more opportunities to shoot in dark places such as indoors. Has occurred, causing a problem of image degradation.

  As such camera shake correction, electronic camera shake correction (EIS) and optical camera shake correction (OIS) have been put into practical use, but optical camera shake correction capable of acquiring a higher quality image is desired. .

  In addition, there are two types of optical image stabilization mechanisms: an overall swing method that corrects by tilting the entire camera, and a lens shift method that moves the autofocus unit including the lens in the direction perpendicular to the optical axis. A lens shift system that can be turned back is desired.

  For example, Patent Document 1 discloses a lens driving device including such a lens shift type optical image stabilization mechanism. The lens driving device disclosed in Patent Document 1 includes an auto drive unit including a first driving member that is an actuator for autofocus that moves a lens in an optical axis direction on four suspension wires implanted in a fixed base in the device. The focus unit has a support mechanism on which it is suspended. The support mechanism of this Patent Document 1 is used for camera shake correction in which two suspension wires are used to form a pair of parallel link mechanisms and two sets are used to drive the autofocus unit in the direction perpendicular to the optical axis. By operating the second drive member consisting of a coil and magnet that are actuators, the straightness of the autofocus unit in the direction perpendicular to the optical axis, that is, the parallelism between the fixed base and the autofocus unit during camera shake correction is ensured. Yes.

JP 2011-227428 A

  However, since the first drive member for autofocus is included in the driven portion when the camera shake correction is performed by the camera shake correction second drive member, the weight driven by the camera shake correction second drive member is heavy. It is getting bigger. For this reason, there is a problem in that the load applied to the camera shake correction unit during a drop impact or the like increases, and the output required for the second drive member increases, so that the power consumption increases.

  The present application can reduce the weight of the driven part driven by the second driving member for correcting camera shake, and can improve the impact resistance, reduce the power consumption of the second driving member, and reduce the size of the entire apparatus. An object of the present invention is to provide a lens driving device and a camera unit that can be used.

  The lens driving device of the present invention holds a fixed base, a lens holding member holding one or more lenses, and the lens holding member so as to be movable in the optical axis direction, and the fixed base is orthogonal to the optical axis. A movable base that is movably supported by the motor, a first drive member that drives the lens holding member in the optical axis direction with respect to the fixed base, and a holding base that is held by either the fixed base or the lens holding member. And a second drive member that has a coil held on the other side and drives the movable base in the orthogonal direction with respect to the fixed base by using the coil and the magnet. 1 drive member is hold | maintained at the said fixed stand, It is characterized by the above-mentioned.

  According to this configuration, since the first drive member is held on the fixed base, the second drive member is configured to drive the lens holding member in the direction orthogonal to the optical axis with respect to the fixed base. The driven portion driven by the second drive member can be reduced in weight, and the impact resistance can be improved, and the power consumption of the second drive member can be saved. And the size of the entire apparatus can be reduced.

  In another aspect, in the lens driving device, the first driving member and the lens holding member are in contact with each other so as to be slidable in the orthogonal direction.

  According to this configuration, the lens holding member moves smoothly in the direction perpendicular to the optical axis. Thereby, further labor saving of the power consumption of the second drive member can be achieved.

  In another aspect, the lens driving device further includes an urging member that urges the lens holding member, and the lens holding member contacts the first driving member from one direction side in the optical axis direction. The biasing member is biased to bias the lens holding member from the one direction side in the optical axis direction to the first drive member side.

  According to this configuration, the urging member can keep the lens holding member constantly in contact with the first drive member. Thereby, the lens holding member can always be moved in the optical axis direction by the first drive member.

  In another aspect, in the lens driving device, the fixing base has a substantially rectangular shape, and the first driving member is disposed at any one corner of the fixing base. To do.

  According to this configuration, since the first driving member is arranged at any one corner of the fixed base, the arrangement efficiency of the first driving member can be improved, and the lens driving device can be increased in size. Can be prevented.

  In another aspect, in the lens driving device, the first drive member includes an electromechanical conversion element, a drive shaft joined to the electromechanical conversion element, and the drive shaft frictionally engaged with the drive shaft. The lens holding member is slidably contacted with the slider in the orthogonal direction.

  According to this configuration, the slider can be slid with a large output by the small first driving member, the lens holding member can be efficiently driven via the slider, and the lens driving device can be miniaturized.

  According to another aspect of the present invention, there is provided a camera unit including any of the lens driving devices described above and an image sensor mounted on a fixed base of the lens driving device.

  According to this configuration, the second driving member does not need to drive the first driving member together with the lens holding member when the lens holding member is driven in the direction orthogonal to the optical axis, and is driven by the second driving member. It is possible to reduce the weight of the driven part, and to make the camera unit capable of improving impact resistance and saving power consumption of the second driving member.

  The lens driving device and the camera unit of the present invention can reduce the weight of the driven part driven by the second driving member for camera shake correction, improve the impact resistance, reduce the power consumption of the second driving member, and the entire device Can be miniaturized.

It is a schematic side view of the camera unit which has the lens drive device of one embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a perspective view of the 1st actuator main body of the 1st actuator used for the lens drive device of the camera unit of FIG. The schematic diagram explaining the operation of the lens driving device is shown, (a) is a schematic diagram in a state where power is not supplied to the first drive member and the second drive member, and (b) is a result of power supply to the second drive member. FIG. 6C is a schematic diagram of a state in which the lens holding member is driven in a direction orthogonal to the optical axis, and FIG. 10C is a schematic diagram of a state in which the lens holding member is further driven in the optical axis direction by supplying power to the first driving member.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side view of a camera unit having a lens driving device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. In the following description, the Z direction in FIGS. 1 to 6 will be described as a vertical direction (optical axis C direction) in a side view, an X direction as a left and right direction in a plan view, and a Y direction as a front and rear direction in a plan view. .

  The camera unit 1 of the present invention includes a lens driving device 10 and an image sensor 22. The lens driving device 10 includes a fixed base 2, a lens holding member 3, a movable base 4, a first actuator for autofocus (first driving member) 5, and a second actuator for correcting camera shake (second driving member). 6).

  The fixing base 2 is made of a resin material such as LCP (liquid crystal polymer) and has a rectangular shape as shown in FIG. 2 when viewed in plan, that is, in the direction of the optical axis C. The fixing base 2 of this embodiment is formed by injection molding in a form in which electrode terminals (not shown) for supplying power to each of a coil 62 of a first actuator 5 and a second actuator 6 described later are inserted.

  Further, as shown in FIG. 2, the fixing base 2 includes a fixing base optical path through-hole 21 serving as an optical path at the center. In addition, the fixed base 2 includes a first actuator holding portion 23 that holds the first actuator 5 at a corner on the left front side on the upper surface.

  As shown in FIG. 1, the movable table 4 includes a movable table main body 41, two holding shafts 42 as holding units that hold the lens holding member 3, and two urging members 43 that urge the lens holding member 3. And.

  The movable base body 41 is made of a resin material such as LCP (liquid crystal polymer). The movable base body 41 is configured by a rectangular plate-like body having a substantially the same size as the fixed base 2 in a plan view. In addition, the movable table main body 41 includes a movable table optical path through hole (not shown) serving as an optical path at the center.

  The movable base body 41 is supported on the upper side of the fixed base 2 through four suspension wires 44 so as to be movable in the direction perpendicular to the optical axis C.

  Specifically, each suspension wire 44 is made of a bendable stainless steel wire having a thickness of about 80 μm to 100 μm. Each suspension wire 44 has one end fixed to each of the four corners of the fixed base 2 and the other end extended in the direction of the optical axis C to be bonded to the movable base main body 41 with an adhesive (for example, UV moisture). Fixed by curing type).

  The suspension base 44 is bent in the X direction and the Y direction, so that the movable base body 41 can move in the direction perpendicular to the optical axis C with respect to the fixed base 2.

  In this embodiment, each holding shaft 42 is composed of a cylindrical body formed integrally with the movable base body 41 and extends from the lower surface of the movable base body 41 toward the fixed base 2 along the optical axis direction. Has been. The two holding shafts 42 are respectively disposed in the vicinity of the corner on the right front side of the movable base body 41 and in the vicinity of the corner opposite to the corner. .

  Each urging member 43 is constituted by a coil spring in this embodiment. The urging member 43 is disposed between the movable table main body 41 and the lens holding member 3 so that the holding shaft 42 is inserted on the inner peripheral side, whereby the urging member 43 is moved to the lens holding member. 3 is urged toward the fixed base 2 on the lower side of the figure.

  The lens holding member 3 is made of a resin material such as LCP (liquid crystal polymer) and is formed by injection molding. As shown in FIGS. 3 and 4, the lens holding member 3 holds one or more lenses 31 at the center.

  The lens holding member 3 includes two fitting insertion holes 32 and a sliding portion 33 on the outer peripheral portion.

  Each of the holding shafts 42 is movably inserted into the insertion hole 32 at a position corresponding to each of the holding shafts 42, whereby the lens holding member 3 is held by the holding shaft 42.

  The sliding portion 33 slides on a contact portion 54a of the first actuator 5 described later. The sliding portion 33 is formed in a planar shape at a position that is between the two insertion holes 32 in the circumferential direction of the lens holding member 3 and is substantially the same distance as each of the insertion holes 32.

  As shown in FIG. 1, the lens holding member 3 configured as described above is movable so that the holding shaft 42 after the biasing member 43 is inserted is inserted into the insertion hole 32 (see FIG. 3). It is disposed between the main body 41 and the fixed base 2 and is biased toward the fixed base 2 by a biasing member 43.

  In this embodiment, the first actuator 5 includes a first actuator body 5a and a slider 54 as shown in FIG.

  As shown in FIG. 5, the first actuator body 5 a includes a piezoelectric element 51 that is an electromechanical conversion element that expands and contracts in the axial direction, a drive shaft 52 joined to one end of the piezoelectric element 51, and the other end of the piezoelectric element 51. And a weight 53 bonded thereto.

  The weight 53 is for generating a larger displacement on the drive shaft 52 side due to the expansion and contraction of the piezoelectric element 51. In this embodiment, the weight 53 is made of a material having a high specific gravity such as tungsten or a tungsten alloy. The weight 53 may be omitted when the other end of the piezoelectric element 51 is attached to the fixed base 2 and can exhibit the same function as the function of the weight 53.

  The piezoelectric element 51 is an element that converts input electric energy into mechanical energy that expands and contracts, that is, mechanical motion. For example, a piezoelectric element that converts input electric energy into mechanical elastic motion by the piezoelectric effect, and the like It is. Such a piezoelectric element includes, for example, a laminated body and a pair of external electrodes.

  The laminated body is formed by alternately laminating a plurality of thin film (layered) piezoelectric layers made of a piezoelectric material and a conductive thin film (layered) internal electrode layer. In the present embodiment, the laminate has a quadrangular prism shape, but is not limited to this, and may be, for example, a polygonal column shape or a cylindrical shape.

  Each of the plurality of internal electrode layers is configured to face the outside with a pair of outer peripheral side surfaces facing each other. The pair of external electrodes are formed along the stacking direction on the pair of outer peripheral side surfaces in the stacked body, and supply the electric energy to the stacked body, and are sequentially and alternately connected to the plurality of internal electrodes. .

Examples of the piezoelectric material include so-called PZT, lithium niobate (LiNbO ₃ ), potassium niobate tantalate (K (Ta, Nb) O ₃ ), barium titanate (BaTiO ₃ ), lithium tantalate (LiTaO ₃ ), and titanium. An inorganic piezoelectric material such as strontium acid (SrTiO ₃ ).

  The drive shaft 52 is made of CFRP molded in a cylindrical shape with resin so that carbon fibers are arranged in the axial direction. The lower end surface of the drive shaft 52 is bonded to the upper end surface of the piezoelectric element 51 with an adhesive (for example, an epoxy adhesive). In this embodiment, the epoxy adhesive is adhesive (fillet: not shown) that protrudes from the joint surface between the drive shaft 52 and the piezoelectric element 51 and is formed on the piezoelectric element side. The entire region can be used for sliding with the slider 54, and a large stroke can be realized with the short drive shaft 52.

  The slider 54 is formed by press working from a material such as a thin plate-like stainless steel having a thickness of 0.1 to 0.2 mm. The slider 54 includes an abutting portion 54 a that abuts against the sliding portion 33 of the lens holding member 3 at one end.

  In this embodiment, the abutting portion 54a is formed of a protruding portion that protrudes in a hemispherical shape from the upper surface of the slider 54. Thus, the first actuator body 5a is inclined with respect to the optical axis C by projecting the contact portion 54a into a hemispherical shape so as to be able to make point contact with the sliding portion 33 of the lens holding member 3. Even when fixed, the frictional fluctuation of the contact portion can be suppressed, and the influence of driving the lens holding member 3 in the direction of the optical axis C can be reduced.

  Further, as shown in FIG. 3, the slider 54 includes an engaging portion 54 b that is frictionally engaged with the drive shaft 52 so as to be axially slidable at the other end. The engaging portion 54b of this embodiment includes an engaging insertion hole 54c into which the drive shaft 52 is inserted, and a pressing member (figure engaged) by pressing the inner wall of the engaging insertion hole 54c against the drive shaft 52. Not shown).

  The slider 54 is frictionally engaged with the drive shaft 52 of the first actuator body 5a with the contact portion 54a facing upward so that the drive shaft 52 is inserted into the engagement insertion hole 54c.

  Then, as shown in FIG. 2, the first actuator 5 configured as described above is fixed to the first actuator holding portion 23 of the fixing base 2 with an adhesive with the weight 53 side (one end side) facing down. Has been. In this state, the sliding portion 33 of the lens holding member 3 is vertically opposed to the abutting portion 54a and is in contact with the upper side (from one direction side in the optical axis C direction). It is urged to be pressed from above.

  As shown in FIGS. 1 and 2, the second actuator 6 includes a magnet 61 and a coil 62. The coil 62 is fixed to the four sides of the fixed base 2. The magnet 61 is fixed to the lower surface of the lens holding member 3 so as to face each of the coils 62. As described above, since the magnet 61 is arranged on the lens holding member 3 which is a driven portion driven by the second actuator 6, it is not necessary to supply power to the driven side, thereby simplifying the configuration. The coil 62 is not fixed to the fixing base 2 and the magnet 61 is fixed to the lens holding member 3. The coil 62 is fixed to the lens holding member 3 and the magnet 61 is fixed to the fixing base 2. It may be changed as appropriate.

  The magnet 61 is magnetized with an N pole on the lens holding member 3 side and an S pole on the fixed base 2 side.

  When no current flows through the coil 62 configured in this manner, no electromagnetic force is generated between the magnet 61 and the coil 62, and the four suspension wires 44 are bent as shown in FIG. The lens holding member 3 does not move without being deformed. On the other hand, when a current is passed through the coil 62, an electromagnetic force is generated between the magnet 61 and the coil 62, and the four suspension wires 44 are bent and deformed as shown in FIG. The lens holding member 3 is driven in the direction orthogonal to the optical axis C.

  Next, the image sensor 22 will be described. The image sensor 22 performs photoelectric conversion into image signals of R (red), G (green), and B (blue) components according to the amount of light in the optical image of the object (subject) imaged by the imaging optical system. This element outputs to a predetermined image processing circuit (not shown). The imaging element 22 is, for example, a CCD type image sensor, a CMOS type image sensor, or the like.

  As shown in FIG. 1, the imaging element 22 is disposed and fixed on the lower surface of the fixed base 2 opposite to the lens holding member 3 and the movable base 4 so as to close the through hole 21 for the fixed base optical path. Is installed.

  Next, the operation of the lens driving device 10 of the camera unit 1 of the present invention will be described. When the first actuator 5 and the second actuator 6 are not supplied with power, a current is passed through the coil 62 of the second actuator 6 from the state shown in FIG.

  Specifically, for example, when a current is passed through the left and right coils 62 in FIG. 2, as shown in FIG. 6B, the four suspension wires 44 are bent and deformed in the X direction. Driven in the X direction orthogonal to the optical axis C.

  Further, as the movable table 4 is driven in the X direction, the sliding portion 33 of the lens holding member 3 slides on the movable table 4 along the contact portion 54 a of the first actuator 5 and is driven in the X direction. At that time, since the sliding portion 33 and the contact portion 54a are in point contact, the sliding resistance is small, and the sliding portion 33 slides smoothly on the contact portion 54a.

  On the other hand, for example, when a current is passed through the coils 62 on both the front and rear sides in FIG. 2, similarly, the four suspension wires 44 are bent and deformed in the Y direction. Driven in the orthogonal Y direction.

  When driving the lens holding member 3, it is not necessary to drive the first actuator 5 together with the lens holding member 3, and the driven part driven by the second actuator 6 can be reduced in weight, and the impact resistance is improved. The power consumption of the second actuator 6 can be reduced, and the entire apparatus can be reduced in size.

  On the other hand, when electric power is supplied to the piezoelectric element 51 of the first actuator 5, the autofocus operation is performed as follows.

  That is, when electric power is supplied to the piezoelectric element 51 of the first actuator 5, the piezoelectric element 51 vibrates in the axial direction, and the drive shaft 52 reciprocates due to the vibration. Move in the axial direction (optical axis direction).

  More specifically, when a rectangular wave having a predetermined duty ratio is applied to the piezoelectric element 51, the displacement of the piezoelectric element 51 becomes a triangular wave. By changing the duty ratio of the rectangular wave, the amplitude is increased and decreased. Triangular waves with different slopes are generated.

  For example, when the drive shaft 52 is vibrated slowly, the slider 54 that is frictionally engaged with the drive shaft 52 is also moved in accordance with the vibration, and the drive shaft is instantaneously enough to exceed the frictionally engaged friction force. When 52 is vibrated, the slider 54 is left as it is. The slider 54 moves in the axial direction of the drive shaft 52 by repeatedly performing such vibration in the axial direction of the drive shaft 52.

  As the slider 54 moves, the lens holding member 3 in contact with the slider 54 moves in the optical axis direction together with the slider 54 as shown in FIG. At this time, since the lens holding member 3 is pressed against the contact portion of the slider 54 by the urging force of the urging member 43, the lens holding member 3 always follows the movement of the slider 54 in the optical axis direction. The slider 54 moves in the same direction.

  In the above-described embodiment, the urging member 43 is arranged so that each of the two holding shafts 42 is inserted. For example, the urging member 43 may be composed of a single member and disposed so that either one of the two holding shafts 42 is inserted, or disposed above the sliding portion.

DESCRIPTION OF SYMBOLS 1 Camera unit 2 Fixed base 3 Lens holding member 4 Movable base 5 1st actuator (1st drive member)
6 Second actuator (second drive member)
43 Energizing member 10 Lens driving device 22 Imaging element 33 Sliding part 61 Magnet 62 Coil

Claims (6)

A fixed base;
A lens holding member holding one or more lenses;
A movable table that holds the lens holding member so as to be movable in an optical axis direction, and is supported by the fixed table so as to be movable in a direction perpendicular to the optical axis;
A first drive member for driving the lens holding member in the optical axis direction with respect to the fixed base;
A coil held on one of the fixed base and the lens holding member, and a magnet held on the other; the coil and the magnet make the movable base into the fixed base. A second drive member that is driven in the orthogonal direction.
The lens driving device, wherein the first driving member is held by the fixed base.   The lens driving device according to claim 1, wherein the lens holding member is in contact with the first driving member so as to be slidable in the orthogonal direction. A biasing member that biases the lens holding member;
The lens holding member is in contact with the first drive member from one direction side in the optical axis direction,
The lens driving device according to claim 1, wherein the urging member urges the lens holding member from the one direction side in the optical axis direction to the first driving member side. The fixing table has a substantially rectangular shape,
The lens driving device according to claim 1, wherein the first driving member is disposed at any one corner of the fixed base. The first drive member includes an electromechanical transducer, a drive shaft joined to the electromechanical transducer, and a slider that is frictionally engaged with the drive shaft and slides in the axial direction of the drive shaft.
The lens driving device according to claim 1, wherein the lens holding member is in contact with the slider so as to be slidable in the orthogonal direction. The lens driving device according to any one of claims 1 to 5,
An image sensor mounted on a fixed base of the lens driving device;
A camera unit comprising:

Images