JP2017201411A - Lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive device that is advantageous for reduction in weight and can prevent a problem of mutual resonance.SOLUTION: A lens drive device comprises: a front substrate (20) that has a plate main body part (22) having a passing-through hole allowing light to a lens to pass through formed; a base (90) that is arranged approximately in parallel to the plate main body part, and supports the front substrate in a movable manner relative to a direction orthogonal to an optical axis of the lens via a suspension wire group (70); a piezoelectric element unit (40) that has one end part (40a) anchored in a plate lower surface (22b) which is a surface directed to a base side in the plate main body part, and expands/contracts in an optical axis direction of the lens; a drive shaft (42) that is anchored in the other end part (40b) of the piezoelectric element unit; and a lens holder (50) that is frictionally engaged with the drive shaft, and holds the lens.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a lens driving device suitably used for a camera module of a mobile phone, for example.

  As a lens driving device suitably used for a camera module of a cellular phone, a lens driving device in which a movable part that can be moved by a driving means or the like is housed in a fixed part such as a case has been proposed. In such a lens driving device, the optical camera shake correction (OIS) and autofocus (AF) are performed by moving the lens held in the movable part in the optical axis direction and the optical axis orthogonal direction with respect to the image sensor or the like. Can be realized.

  As a driving means built in the lens driving device, for example, a voice coil motor (VCM) composed of a combination of a magnet and a coil can be cited. For example, in Patent Document 1 and the like, there is a lens driving device that realizes optical image stabilization and autofocus by independently controlling a VCM that drives a lens in the optical axis direction and a VCM that drives the lens in a direction orthogonal to the optical axis. Proposed.

International Publication No. 2009/133691

  In a conventional lens driving device incorporating a VCM that drives the lens in the optical axis direction and a VCM that drives the lens in the direction orthogonal to the optical axis, an increase in weight due to an increase in the number of VCMs is a problem. Also, in the structure where the movement of the lens in the direction perpendicular to the optical axis is supported by the suspension wire and the movement of the lens in the optical axis direction is supported by the spring member, the drive frequency is restricted to avoid mutual resonance, and the response speed Have problems with.

  The present invention has been made in view of such a situation, and an object thereof is to provide a lens driving device that is advantageous for weight reduction and can prevent the problem of mutual resonance.

In order to achieve the above object, a lens driving device according to the present invention includes:
A front substrate having a plate body portion in which a passage hole for passing light to the lens is formed;
A base that is disposed substantially parallel to the plate body, and supports the front substrate via a suspension wire group so as to be relatively movable in the direction perpendicular to the optical axis of the lens;
One end portion is fixed to the lower surface of the plate, which is a surface facing the base side in the plate main body portion, and a piezoelectric element portion that expands and contracts in the optical axis direction of the lens;
A drive shaft fixed to the other end of the piezoelectric element portion;
A lens holder that is frictionally engaged with the drive shaft and holds the lens.

In the lens driving device according to the present invention, since the driving means for driving the lens in the optical axis direction is a piezoelectric element portion, the weight and power consumption are reduced compared to the lens driving means for driving the lens in the optical axis direction by VCM. From the viewpoint of In addition, by fixing one end of the piezoelectric element portion to the lower surface of the plate, the front substrate can also serve as a weight for moving the lens holder in the optical axis direction, and a structure for separately preparing a weight Compared to the above, it is advantageous for weight reduction and miniaturization, and since the number of parts is reduced, a cost suppressing effect can be expected. Further, even when a VCM is used for driving in the direction perpendicular to the optical axis, there is no concern about magnetic circuit interference with the driving means in the optical axis direction, which is advantageous for miniaturization.
In addition, since the lens driving device according to the present invention has a structure in which the lens holder is frictionally engaged with the driving shaft, the support structure by the suspension wire group and the light are compared with the conventional structure in which the lens holder is supported by a spring member or the like. Mutual resonance with the support structure in the axial movement direction can be prevented. In addition, the lens driving device in which the lens holder is frictionally engaged with the driving shaft is advantageous in terms of impact resistance as compared with the conventional structure in which the lens holder is supported by the spring member.

Further, for example, the front substrate has a sensor mounting surface that is bent from the plate main body portion to the base side so as to be substantially parallel to the optical axis direction.
A first position detection sensor that is installed on the sensor mounting surface and detects a position of the lens in the optical axis direction;
You may further have a 1st magnet installed in the said lens holder so that it may oppose with a predetermined space | interval with respect to a said 1st position detection sensor.

  By detecting the position of the lens in the optical axis direction using the first position detection sensor, it is possible to realize closed-loop lens position control, and realize high-precision autofocus control using the piezoelectric element. it can. Moreover, the position of the lens holder can be detected easily and accurately by attaching the first position detection sensor to the sensor mounting surface bent from the plate body to the base side and facing the first magnet installed on the lens holder. .

  Further, for example, the lens holder is connected to the plate main body portion, and an auxiliary shaft portion extending substantially parallel to the optical axis direction from the lower surface of the plate toward the base side is provided in the direction orthogonal to the optical axis. A pair of anti-rotation protrusions may be sandwiched from both sides, and the first magnet may be installed on the anti-rotation protrusion.

  The anti-rotation protrusion provided so as to sandwich the auxiliary shaft portion prevents the lens holder from rotating with respect to the front substrate, and realizes stable movement and position control of the lens holder. Further, by providing the first magnet on the rotation stop projection, it is possible to prevent an unexpected change in position between the first magnet and the first position detection sensor due to rotation of the lens holder and the like, and highly accurate position detection is possible. It becomes possible.

  Further, for example, the suspension wire group includes four suspension wires, two of the four suspension wires are electrically connected to the piezoelectric element portion, and the remaining two are The first position detection sensor may be electrically connected.

  By using four suspension wires, the base portion can support the front substrate in a well-balanced manner while being movable in the direction perpendicular to the optical axis. In addition, by using two of the four suspension wires as a part for driving the piezoelectric element unit and the other two as part of the position detecting wiring, the control process of the piezoelectric element unit and the first position detection sensor Both detection signal processes can be performed on the base side. Thereby, the operation of the lens driving unit can be centrally controlled from the base unit without providing a processor or the like on the front substrate.

Further, for example, the base may be provided with a second position detection sensor and a third position detection sensor for detecting the position of the lens in the direction perpendicular to the optical axis,
In the second position detection sensor and the third position detection sensor, the detection axes of each other form an angle of approximately 90 degrees, and the extension lines of the detection axes of the second position detection sensor and the third position detection sensor intersect in the vicinity of the optical axis extension position of the lens. May be arranged.

  The second position detection sensor and the third position detection sensor can detect the positions of the lens and the front substrate in the direction perpendicular to the optical axis, and can perform highly accurate camera shake correction control. In addition, by disposing the second and third position detection sensors so that the extension lines of the detection axes intersect each other in the vicinity of the optical axis extension position of the lens, the detection position shift due to the rolling of the lens or the like can be prevented and high accuracy can be achieved. Position detection is possible.

Further, for example, the base may have a substantially rectangular outer peripheral shape when viewed from the optical axis direction,
The second position detection sensor and the third position detection sensor may be arranged at a corner of the base,
A driving coil for driving the lens in the direction orthogonal to the optical axis is disposed at a predetermined distance from the driving magnet connected to the lower surface of the plate at the side of the base located between the corners. It may be arranged so as to be opposed to each other.

  By arranging the position detection sensor at the corner of the base and arranging the coil at the side of the base, it is possible to arrange the driving coil by using each side greatly. The thrust of the VCM composed of magnets can be increased.

  The front substrate may include a center-of-gravity adjusting unit disposed at a position that is substantially symmetrical with respect to a fixed position of the piezoelectric element unit with respect to the optical axis of the lens.

  The lens driving device having such a center of gravity adjustment unit prevents the center of gravity of the mass body supported by the suspension wire group from being greatly separated from the optical axis at the connection position of the front substrate and the suspension wire group. It makes position control in the orthogonal direction easy and realizes highly accurate position control.

FIG. 1 is an overall perspective view of a lens driving device according to an embodiment of the present invention. FIG. 2 is a schematic exploded perspective view of the lens driving device shown in FIG. 3 is an exploded perspective view of the first unit shown in FIG. 4 is an exploded perspective view of the second unit shown in FIG. FIG. 5 is a perspective view of a part of the first unit shown in FIG. 2 as viewed obliquely from below. FIG. 6 is an enlarged perspective view showing a fixed portion between the piezoelectric element portion and the front substrate. FIG. 7 is an enlarged perspective view showing the rotation stopper protrusion and its peripheral part. FIG. 8 is a partial cross-sectional view showing a connection portion between the suspension wire, the second base portion, and the front substrate. FIG. 9 is a perspective view of the first base of the first unit as viewed from below. FIG. 10 is a plan view of the second unit as viewed from above. FIG. 11 is a perspective view illustrating a part of a lens driving device according to a modification.

  FIG. 1 is a perspective view of a lens driving device 10 according to an embodiment of the present invention. The lens driving device 10 has a substantially rectangular parallelepiped outer shape, and is mounted on, for example, a mobile phone as a device for driving a camera lens. The size of the lens driving device 10 is not particularly limited, but when mounted on a mobile phone, the outer diameter when viewed from above (Z-axis positive direction) is set to about 8.5 mm × 8.5 mm. .

  As shown in FIG. 2, which is a schematic exploded view, the lens driving device 10 includes a case 12, a first unit 14, a second unit 16, a suspension wire group 70, and the like. The case 12 is fixed to the second unit 16 so as to cover the first unit 14 from above, and constitutes an exterior housing of the lens driving device 10 together with the second unit 16. A lens (not shown) is attached to a lens holder 50 (see FIG. 3) of the first unit 14 described later. The lens driving device 10 realizes optical camera shake correction (OIS) and autofocus (AF) by moving the lens attached to the lens holder 50 in the optical axis direction and the optical axis orthogonal direction of the lens. In the description of the lens driving device 10, as shown in FIG. 1, the direction parallel to the optical axis is described as the Z-axis direction, and the directions orthogonal to the Z-axis are described as the X-axis direction and the Y-axis direction. The optical axis direction includes directions parallel to the Z axis and the optical axis, and the optical axis orthogonal direction includes directions parallel to the X axis and the Y axis.

  The first unit 14 is accommodated in an exterior casing constituted by the case 12 and the second unit 16. The entire first unit 14 is driven by a driving VCM described later, and moves relative to the second unit 16 in the direction perpendicular to the optical axis. FIG. 3 is an exploded perspective view of the first unit 14 shown in FIG. As shown in FIG. 3, the first unit 14 includes a front substrate 20, a piezoelectric actuator unit including a piezoelectric element unit 40 and a drive shaft 42, a lens holder 50, a first base 60, and the like.

  The front substrate 20 has a two-layer structure of a first plate 20a and a first FPC 20b. The material of the first plate 20a is not particularly limited, such as a metal, ceramic, resin, or composite material, but an insulating material is preferable, and more specifically, an insulating metal or ceramic material is preferable. The first FPC 20b is configured by so-called flexible printed circuits. The front substrate 20 is not limited to a combination of a plate material such as the first plate 20a and a flexible printed wiring board, and may be formed of a rigid substrate such as a glass epoxy substrate.

  The first FPC 20b is attached so as to cover the first plate 20a from above. The first FPC 20b constitutes the upper layer of the front substrate 20, and the first plate 20a constitutes the lower layer of the front substrate 20. The front substrate 20 includes a plate main body portion 22 having a passage hole 22c through which light to the lens passes, and a sensor mounting surface 24 bent from the plate main body portion 22 to the base side so as to be substantially parallel to the optical axis. Have

  One end portion 40 a of the piezoelectric element portion 40 is fixed to the plate lower surface 22 b that is a surface facing the second base 90 side (Z-axis negative direction side) in the plate main body portion 22. FIG. 5 is a perspective view of the mounting state of the front substrate 20, the piezoelectric actuator unit, the lens holder 50, and the like observed from the plate lower surface 22b side, and FIG. 6 is an enlarged view of the periphery of the piezoelectric actuator unit in FIG. .

  As shown in FIG. 6B showing a state before the piezoelectric actuator unit is fixed, the plate lower surface 22b has a piezoelectric element attachment portion 22ba for fixing the piezoelectric element portion 40. A hole 20aa that is a through hole formed in the first plate 20a is formed on both sides of the piezoelectric element mounting portion 22ba, and the piezoelectric element connection portion 20ba that is a part of the first FPC 20b passes through the hole 20aa. And exposed to the plate lower surface 22b side.

  As shown in FIG. 6A, the piezoelectric element portion 40 has an outer shape of a substantially rectangular parallelepiped shape having a pair of end faces that face in the vertical direction and four side faces that face in the direction perpendicular to the optical axis. An external electrode for inputting is formed. The piezoelectric element section 40 has a laminated structure in which piezoelectric layers made of a piezoelectric material and internal electrode layers connected to external electrodes are alternately laminated, and drive signals (voltages) input via the external electrodes. It expands and contracts in the optical axis direction according to the signal.

  The piezoelectric element portion 40 is attached to the plate lower surface 22b by fixing one end portion 40a to the piezoelectric element attachment portion 22ba by bonding or the like. In addition, the piezoelectric element connection portion 20ba is electrically connected to the external electrode of the piezoelectric element portion 40, and a drive signal is input to the piezoelectric element portion 40 via the first FPC 20b.

  A drive shaft 42 is fixed to the other end 40 b of the piezoelectric element portion 40. The drive shaft 42 has a substantially cylindrical outer shape, and the upper circular end surface is fixed to the other end portion 40b by adhesion or the like. The drive shaft 42 moves in the optical axis direction (vertical direction) corresponding to the expansion and contraction of the piezoelectric element portion 40.

  A lens holder 50 shown in FIG. 3 includes a bottomless cylindrical tube portion 51, a support portion 52 connected to the side surface of the tube portion 51, and a rotation stop protrusion 54. A lens is fixed to the inner peripheral surface of the cylindrical portion 51. The light that has passed through the passage hole 22c of the plate body 22 enters the lens from the Z-axis positive direction side and is emitted from the Z-axis negative direction side of the lens.

  A shaft receiving surface 52 a that frictionally engages with the outer peripheral surface of the drive shaft 42 is formed on the side surface of the support portion 52 using the elastic force of the pressing spring 34. As shown in FIG. 5, the shaft receiving surface 52a has a groove shape that opens to the outer diameter side so that the shaft receiving surface 52a can be engaged with the driving shaft 42, and between the tip of the pressing spring 34 and the shaft receiving surface 52a. The lens holder 50 is frictionally engaged with the drive shaft 42 by sandwiching 42. The base portion of the pressing spring 34 is fixed to the support portion 52.

  As shown in FIG. 5, in the lens holder 50, a pair of rotation stop protrusions 54 protrudes from the tube portion 51 in the direction perpendicular to the optical axis. The pair of rotation stopper protrusions 54 extend substantially parallel to each other, and are arranged so as to sandwich the auxiliary shaft portion 32 from both sides in the direction perpendicular to the optical axis. The upper end of the auxiliary shaft portion 32 is connected to the plate main body portion 22, and the auxiliary shaft portion 32 extends from the plate lower surface 22 b toward the base side so as to be substantially parallel to the optical axis direction. It is preferable from the viewpoint of preventing the rotation of the lens holder 50 that the rotation stop protrusion 54 is provided at a position away from the shaft receiving surface 52a along the rotation direction about the optical axis. For example, the rotation stop protrusion 54 is preferably provided at a position rotated 90 to 270 degrees around the optical axis with respect to the shaft receiving surface 52a.

  A first magnet 44 is installed on the side surface of one rotation stop protrusion 54. As shown in FIG. 7 which is an enlarged view, the first magnet 44 is installed on the rotation stop protrusion 54 so as to face the first position detection sensor 30 with a predetermined interval. The first position detection sensor 30 is installed on a sensor mounting surface 24 that is substantially parallel to the optical axis direction, and has a detection axis in the optical axis direction. The first position detection sensor 30 is constituted by a magnetic sensor such as an MR sensor (a sensor using a magnetoresistive element (MR element)), for example, and changes the lens around the sensor by a first magnet 44 that is a magnetic medium. And the position of the optical axis direction of the lens holder 50 is detected.

  As shown in FIG. 9 and the like, the first base 60 shown in FIG. 3 includes a bottom surface portion 60b having a substantially rectangular outer peripheral shape with a through hole formed in the center, and a connection portion protruding upward from both ends of the bottom surface portion 60b. And have. The upper end surface 60a of the connecting portion is fixed to the plate lower surface 22b of the plate main body portion 22, and the first base 60 is supported by the front substrate 20 positioned above (see FIG. 2).

  As shown in FIG. 9, a drive magnetized portion 62 and a detection magnetized portion 64 are formed on the lower surface of the bottom surface portion 60b. The drive magnetizing portions 62 are disposed on the four sides of the bottom surface portion 60b, and the detection magnetized portions 64 are disposed on the two corners. The drive magnetizing portion 62 and the detection magnetizing portion 64 are permanent magnets, and the polarization direction of the permanent magnet constituting the drive magnetizing portion 62 is the X-axis direction or the Y-axis direction. The polarization direction of the permanent magnet constituting the portion 64 is the radial direction of the lens.

  The drive magnetizing unit 62, together with the drive coil 80a included in the FP coil 80 of the second unit 16, constitutes a VCM that moves the entire first unit 14 in the direction perpendicular to the optical axis. Further, the detection magnetizing portion 64 functions as a magnetic medium for the second position detection sensor 84 and the third position detection sensor 86 of the second unit. The entire first base 60 is integrally formed of a plastic magnet, and only the drive magnetized portion 62 and the detection magnetized portion 64 are magnetized. However, the configuration of the first base 60 is not limited to this, and after forming other portions excluding the portions corresponding to the drive magnetizing portion 62 and the detection magnetizing portion 64, a permanent magnet is attached thereto. The first base may be formed by using a driving magnetized portion and a detecting magnetized portion.

  The second unit 16 shown in FIG. 2 is connected to the first unit 14 via the suspension wire group 70. FIG. 4 is an exploded perspective view of the second unit 16. The second unit 16 includes an FP coil 80, a tape 82, a second position detection sensor 84 and a third position detection sensor 86, a second base 90 as a base portion, and the like.

  The second base 90 includes a bottom 94 and a second FPC 92, and the second FPC 92 is attached to the upper surface of the bottom 94. The second FPC 92 is composed of a flexible printed wiring board as in the first FPC 20b. The second FPC 92 is provided with a terminal portion for receiving a control signal from the outside of the lens driving device 10 and receiving power supply. The material of the bottom 94 is not particularly limited, but the bottom 94 can be formed of resin or the like.

  As shown in FIG. 8, the second base 90 is disposed substantially parallel to the plate main body portion 22 of the front substrate 20. The second base 90 supports the front substrate 20 via the suspension wire group 70 so as to be relatively movable in the direction perpendicular to the optical axis of the lens.

  The suspension wire group 70 includes four suspension wires 70a to 70d. The upper end portions of the suspension wires 70a to 70d are fixed to the wire attaching portion 25 of the front substrate 20 and are electrically connected to the first FPC 20b. As shown in FIG. 8B, the wire attachment portion 25 is composed of arm-like protrusions that protrude in the radial direction from the four corners of the plate main body portion 22, and an unexpected impact is applied to the lens driving device 10. In this case, it functions as an impact buffer and prevents the suspension wires 70a to 70d from buckling. The number of suspension wires included in the suspension wire group 70 is not particularly limited as long as it is three or more, but is four from the viewpoint of a structure that can be easily assembled and can support the lens in a balanced manner. It is preferable.

  The lower ends of the suspension wires 70a to 70d are fixed to the four corners of the second base 90 and are electrically connected to the second FPC 92 (see FIGS. 8A and 8B). Therefore, each of the suspension wires 70a to 70d functions as a wiring portion that electrically connects the first FPC 20b and the second FPC 92. Two of the four suspension wires 70a to 70d are electrically connected to the piezoelectric element portion 40 via the first FPC 20b, and the other two are connected to the first position detection sensor 30 via the first FPC 20b. Electrically connected. Thereby, in the lens driving device 10, the driving operation of the lens driving device 10 including the closed-loop lens position control in the optical axis direction can be controlled from the second base 90 side without providing a processor or the like on the front substrate 20. .

  As shown in FIGS. 8A and 8B, the suspension wires 70 a to 70 d pass through the groove portions 65 formed at the four corners of the first base 60. A conical portion 65a that facilitates passage of the upper ends of the suspension wires 70a to 70d is formed on the upper portion of the groove portion 65. A damper gel may be injected into the groove 65.

  As shown in FIG. 4, a second position detection sensor 84 and a third position detection sensor 86 are installed on the upper surface of the second FPC 92 that constitutes the upper portion of the second base 90. Furthermore, an FP coil 80 is installed on the upper surface of the second FPC 92 via a tape 82 for insulation. The second position detection sensor 84 and the third position detection sensor 86 are configured by a magnetic sensor such as a Hall sensor or an MR sensor. The FP coil 80 is constituted by a coil using so-called flexible printed circuits, and the FP coil 80 includes four drive coils 80a as will be described later.

  As shown in FIG. 10, the second base 90 has a substantially rectangular outer peripheral shape when viewed from the optical axis direction. The second position detection sensor 84 and the third position detection sensor 86 are disposed at two corners 90 a of the second base 90, and face the detection magnetized portions 64 formed on the lower surface of the first base 60. (See FIG. 9). The second position detection sensor 84 and the third position detection sensor 86 detect the position of the lens in the direction perpendicular to the optical axis by detecting the magnetism of the detection magnetizing portion 64 that moves with the front substrate 20.

  In the second position detection sensor 84 and the third position detection sensor 86, the detection axes 84a and 86a form an angle of approximately 90 degrees, and the extension lines of the detection axes 84a and 86a indicate the optical axis extension position of the lens. It arrange | positions so that it may cross in L vicinity. With this arrangement, it is possible to easily calculate the position of the lens in the direction perpendicular to the optical axis, and because the outer peripheral direction of the lens is substantially perpendicular to the detection axis, a false signal associated with the rotation of the lens Can be suppressed, and highly accurate position detection can be realized.

As shown in FIG. 10, the driving coil 80a included in the FP coil 80 is disposed on the four side portions 90b located between the corner portions 90a. The drive coil 80a is opposed to the drive magnetized portion 62 formed on the lower surface of the first base 60 (see FIG. 9). The second position detection sensor 84 and the second position detection sensor 86 may be arranged at the center of the side portion 90b, and the driving coil of the side portion 90b may be configured by two coils that sandwich the sensor from both sides. From the viewpoint of obtaining a high thrust from the VCM, it is advantageous to dispose the second position detection sensor 84 and the third position detection sensor 86 in the corner portion 90a.

  The driving coil 80 a is electrically connected to the second FPC 92 and is supplied with power through the second FPC 92. The piezoelectric element section 40 shown in FIG. 5 is also electrically connected to the second FPC 92 via the first FPC 20b and the suspension wire group 70, and a drive signal is input via the second FPC 92. Further, the output of the first position detection sensor 30 installed on the sensor mounting surface 24 is also transmitted to the second FPC 92 via the first FPC 20b and the suspension wire group 70, and the second position detection sensor 84 installed on the second FPC 92 and The output of the third position detection sensor 86 is also transmitted to the second FPC 92.

  As described above, the lens driving device 10 according to the present embodiment is advantageous in terms of weight reduction and power saving because the driving means for driving the lens in the optical axis direction is the piezoelectric element portion 40. Further, by fixing one end portion 40a of the piezoelectric element portion 40 to the plate lower surface 22b, the front substrate 20 can also serve as a weight for moving the lens holder 50 in the optical axis direction. This is also advantageous for weight reduction and size reduction, and since the number of parts is reduced, a cost suppressing effect can be expected. Further, the driving means by the piezoelectric element section 40 is free from the concern of magnetic circuit interference with other permanent magnets such as the driving magnetizing section 62, and this is also advantageous for weight reduction and size reduction.

  Further, since the lens driving device 10 has a structure in which the lens holder 50 is frictionally engaged with the driving shaft 42, mutual resonance between the support structure by the suspension wire group 70 and the support structure in the optical axis moving direction can be prevented. Therefore, it is possible to realize drive control with good responsiveness by increasing the drive frequency of each drive means. Further, the lens driving device 10 having a structure in which the lens holder 50 is frictionally engaged with the driving shaft 42 is advantageous in terms of impact resistance as compared with a conventional structure in which the lens holder is supported by a spring member. Further, since the lens driving device 10 has a structure in which one end portion 40a of the piezoelectric element portion 40 is fixed to the front substrate 20 that is also a wiring board, the FPC is directly connected without using a wire connection or the like. In this simple method, electrical connection to the piezoelectric element portion 40 can be easily performed.

  The lens driving device 10 can realize closed-loop lens position control by the first position detection sensor 30 installed on the front substrate 20 and the first magnet 44 installed on the lens holder 50. High performance autofocus control can be realized. Since the number of suspension wires used as wiring to the first position detection sensor 30 can be reduced to two by using an MR sensor instead of a hall sensor as the first position detection sensor 30, the second base From the viewpoint of realizing centralized control from the 90 side, it is preferable to use an MR sensor as the first position detection sensor 30.

  The above-described embodiment describes an example of the present invention, and the present invention is not limited to the lens driving device 10 described above. Each element included in the lens driving device 10 can be changed without departing from the gist of the invention.

  FIG. 11 is a schematic perspective view showing the internal structure of the lens driving device 100 according to a modification. Since the lens driving device 100 is the same as the lens driving device 10 except that the shape of the front substrate 120 is different, description of common parts is omitted. In FIG. 11, the case 12 and the first base of the lens driving device 100 are not displayed.

  The front substrate 120 includes a center of gravity adjustment unit 126 that is disposed at a position that is substantially symmetrical with respect to the fixed position of the piezoelectric element unit 40 with respect to the optical axis of the lens. The center-of-gravity adjusting portion 126 is formed by extending a part of the first plate 20 a downward from the plate body portion 122. The center-of-gravity adjusting unit 126 prevents the center of gravity of the mass body supported by the suspension wire group 70 from being greatly separated from the optical axis at the position in the Z direction where the front substrate 120 is connected to the suspension wire group 70. There is an effect of facilitating position control in the direction perpendicular to the axis.

DESCRIPTION OF SYMBOLS 10, 100 ... Lens drive device 14 ... 1st unit 20, 120 ... Front substrate 20a ... 1st plate 20b ... 1st FPC
22, 122 ... Plate body 22c ... Pass-through hole 22b ... Plate lower surface 24 ... Sensor mounting surface 30 ... First position detection sensor 32 ... Auxiliary shaft 40 ... Piezoelectric element 40a ... One end 40b ... Other end 42 ... drive shaft 44 ... first magnet 50 ... lens holder 54 ... rotation stop projection 60 ... first base 62 ... drive magnetized portion 70a to 70d ... suspension wire 16 ... second unit 80 ... FP coil 80a ... drive coil 84 ... 2nd position detection sensor 86 ... 3rd position detection sensor 84a, 86a ... detection axis 90 ... 2nd base 90a ... corner | angular part 90b ... side part 92 ... 2nd FPC
126 ... Center of gravity adjustment section

Claims (7)

A front substrate having a plate body portion in which a passage hole for passing light to the lens is formed;
A base that is disposed substantially parallel to the plate body, and supports the front substrate via a suspension wire group so as to be relatively movable in the direction perpendicular to the optical axis of the lens;
One end portion is fixed to the lower surface of the plate, which is a surface facing the base side in the plate main body portion, and a piezoelectric element portion that expands and contracts in the optical axis direction of the lens;
A drive shaft fixed to the other end of the piezoelectric element portion;
And a lens holder that is frictionally engaged with the drive shaft and holds the lens. The front substrate has a sensor mounting surface bent from the plate main body portion toward the base side so as to be substantially parallel to the optical axis direction.
A first position detection sensor that is installed on the sensor mounting surface and detects a position of the lens in the optical axis direction;
The lens driving device according to claim 1, further comprising: a first magnet installed on the lens holder so as to face the first position detection sensor with a predetermined interval. The lens holder is connected to the plate main body, and a pair of auxiliary shafts that extend from the lower surface of the plate toward the base and substantially parallel to the optical axis direction from both sides of the optical axis orthogonal direction. Have anti-rotation protrusions,
The lens driving device according to claim 1, wherein the first magnet is disposed on the rotation stop protrusion.   The suspension wire group includes four suspension wires, two of the four suspension wires are electrically connected to the piezoelectric element portion, and the other two are in the first position. The lens driving device according to any one of claims 1 to 3, wherein the lens driving device is electrically connected to a detection sensor. The base is provided with a second position detection sensor and a third position detection sensor for detecting the position of the lens in the direction perpendicular to the optical axis,
In the second position detection sensor and the third position detection sensor, the detection axes of each other form an angle of approximately 90 degrees, and the extension lines of the detection axes of the second position detection sensor and the third position detection sensor intersect in the vicinity of the optical axis extension position of the lens. The lens driving device according to any one of claims 1 to 4, wherein the lens driving device is disposed on the lens. The base has a substantially rectangular outer peripheral shape when viewed from the optical axis direction,
The second position detection sensor and the third position detection sensor are arranged at corners of the base,
A driving coil for driving the lens in the direction orthogonal to the optical axis is disposed at a predetermined distance from the driving magnet connected to the lower surface of the plate at the side of the base located between the corners. The lens driving device according to claim 5, wherein the lens driving device is disposed so as to face each other with a gap therebetween.   7. The front substrate includes a center of gravity adjustment portion disposed at a position substantially symmetrical with respect to a fixed position of the piezoelectric element portion with respect to the optical axis of the lens. The lens driving device according to any one of the above.

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