BACKGROUND OF THE INVENTION

The present invention relates to an image-stabilizer lens drive device favorably used for camera module of mobile phones, for example.

In lens drive devices favorably used for camera module of mobile phones, developed are image-stabilizer lens drive devices that carry out optical image stabilization (OIS) by moving a lens holder holding a lens in orthogonal directions to an optical axis (e.g., Patent Document 1). In such lens drive devices, electric power is supplied to a drive coil for driving the lens via FPC, wirings of rigid board, springs, or the like.

A conductive connection member, such as solder, is used for a connection part between each wiring of the board, between wirings of the board and the springs, or the like. The connection member, such as solder, is melted and solidified by heating and connects the wirings. In conventional lens drive devices, however, particles are generated from the connection member and may attach onto an optical path of the lens drive device and flow into an imaging element, and this is a problem. In the image-stabilizer lens drive devices, many coils and movable members tend to be employed, and it is thereby necessary to effectively prevent generation of particles caused by impact from outside.

Patent Document 1: JP2016035598 (A)

BRIEF SUMMARY OF INVENTION

The present invention has been achieved under such circumstances. It is an object of the invention to provide a lens drive device capable of preventing particles from flowing into an optical path.

To achieve the above object, a lens drive device according to the present invention includes.

a movable unit including a magnet and a lens holder for holding a lens;

a fixed unit including:

- a coil board including a coil facing the magnet and configured to drive the magnet in orthogonal directions to an optical axis of the lens and a coil wiring connected to the coil; and
- a base board disposed on the other side of the magnet across the coil board and including a base wiring and an opening through which the optical axis of the lens passes; and

a support portion configured to relatively movably connect the movable unit o the fixed unit and support the movable unit to the fixed unit,

wherein a first conductive portion conductively connecting the coil wiring and the base wiring in the fixed unit is disposed away from an opening periphery of the opening to an outside in a radial direction.

In the lens drive device according to the present invention, the first conductive portion connecting the coil wiring and the base wiring is disposed away from the opening periphery of the opening to the outside in the radial direction. Thus, the first conductive portion is prevented from colliding with other members, such as the lens holder, and can be prevented from generating particles. Since the first conductive portion is not exposed to the opening periphery, the particles generated from the first conductive portion can be prevented from flowing into the optical path. Since the first conductive portion is not exposed to the opening, the lens drive device according to the present invention is also advantageous in connection reliability, compared to prior arts including a conductive portion exposed to an opening.

For example, the first conductive portion and the opening periphery may be divided by a resin portion.

When the first conductive portion is not merely away from the opening periphery but is divided from the opening periphery by the resin portion, it is possible to effectively prevent the generation of particles from the first conductive portion and the inflow of the particles onto the optical path.

For example, a resin portion connecting the coil board and the base board may surround and cover the first conductive portion when viewed from the optical axis of the lens.

When the resin portion surrounds and covers the first conductive portion, it is possible to more effectively prevent the generation of particles from the first conductive portion and the inflow of the particles onto the optical path, and it is also possible to prevent the conductive particles and water from attaching to the first conductive portion and prevent a problem in insulation from arising.

In the lens drive device according to the present invention, for example, a plurality of resin portions may be arranged intermittently around the opening, In the lens drive device according to the present invention, for example, the resin portion may be disposed continuously to surround the opening.

When the plurality of resin portions is arranged intermittently around the opening or when the resin portion is disposed to surround the opening, particles can effectively be prevented from flowing into the opening. When the resin portion connects the base board and the coil board, the connection strength between the base board and the coil board is expected to increase.

For example, at least a part of the resin portion may contain metal particles unevenly distributed in a resin.

When the first conductive portion is covered with the resin portion, there is a concern about decrease in heat dissipation efficiency compared to when the first conductive portion is exposed. When metal particles are contained in a resin, however, the first conductive portion has good heat dissipation characteristics even if it is covered with the resin portion. Incidentally, the metal particles are preferably unevenly distributed in the resin as long as it maintains insulation property.

For example, the base board may include a metallic plate with the opening, and the base wiring may be disposed near the coil board on the plate.

The base board can be thin while securing the strength and thereby contributes to downsizing of the entire lens drive device. The metallic plate is also advantageous in enhancement of heat dissipation of the lens drive device.

For example, a spacer defining a space between the coil board and the base board may be disposed therebetween.

The lens drive device with the space can prevent manufacturing variation in distance between the coil board and the base board and can appropriately prevent a problem of variation in shape of the first conductive portion or the resin portion connecting the coil board and the base board caused by variation in gap between the coil board and the base board.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exterior view of a lens drive device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the lens drive device shown in FIG. 1 without a cover.

FIG. 3 is a cross-sectional view of the lens drive device shown in FIG. 1,

FIG. 4 is a perspective view illustrating a coil board, a base board, and their peripheral members contained in the lens drive device shown in FIG. 1.

FIG. 5 is a perspective view illustrating a base board and its peripheral members contained in the lens drive device shown in FIG. 1.

FIG. 6 is a plane view illustrating a base board and its peripheral members contained in the lens drive device shown in FIG. 1

FIG. 7 is a partial enlarged view of the base board and its peripheral members shown in FIG. 6.

FIG. 8A is a partially enlarged view illustrating a vicinity of a first conductive portion contained in the lens drive device shown in FIG. 1, FIG. 8B is a conceptual view of a second resin portion shown in FIG. 8A, and FIG. 8C is a conceptual view of a first resin portion shown in FIG. 8A.

FIG. 9 is a partial perspective view illustrating a base board before a first conductive portion is formed.

FIG. 10 is a partial perspective view illustrating a coil board before a first conductive portion is formed.

FIG. 11 is a plane view illustrating a base board and its peripheral members according to First Variation.

FIG. 12 is a plane view illustrating a base board and its peripheral members according to Second Variation.

DETAILED DESCRIPTION OF INVENTION

Hereinafter, the present invention is described based on an embodiment shown in the figures.

As shown in FIG. 1, a lens drive device 2 according to an embodiment of the present invention holds a lens 100 at a central part of the lens drive device 2 and drives the lens 100. The lens drive device 2 has a substantially rectangular outer shape when viewed from an optical axis O of the lens 100. The lens drive device 2 includes a case 8 configured to cover the inside of the lens drive device 2 from the positive size hi the Z-axis direction (the incoming side in the optical axis). The case 8 is provided with a through hole where the optical axis O of the lens 100 passes.

FIG. 2 is a perspective view of the lens drive device 2 shown in FIG. 1 without the case 8. The lens drive device 2 includes a movable unit 3, a fixed unit 4, and suspension wires 16. In the image stabilization, the movable unit 3 moves in orthogonal. directions to the optical axis along with the lens 100 held by the lens holder 40, and the fixed unit 4 generates a relative displacement to the movable unit 3. The suspension wires 16 connect the movable unit 3 relatively movably to the fixed unit 4 and are support portions for the movable unit 3 to the fixed unit 4.

FIG. 3 is a cross-sectional view of the lens drive device 2 shown in FIG, 2, but does not illustrate the lens 100 for easy view of other members. As shown in FIG. 3, the movable unit 3 is disposed inside the case 8 shown in FIG. 1 and includes magnets 80 and a lens holder 40 for holding the lens 100. In addition to the lens holder 40 and the magnets 80, the movable unit 3 includes a front spring 90, a rear spring 50, a frame 60, a focus coil 46, and the like.

As shown in FIG. 4, the fixed unit 4 includes a coil board 30 and a base board 20. The coil board 30 includes image-stabilizer coils 32 (see FIG. 4) for driving the magnets 80 of the movable unit 3 in orthogonal directions to the optical axis of the lens 100. The base board 20 includes base wirings 21 (see FIG. 6) configured to be electrically connected to a coil wiring 31 or so of the coil board 30. Connector parts 23 (a part of the base board 20) are exposed from the ease 8 to the negative side in the Z-axis direction (the outgoing side in the optical axis).

The lens drive device 2 is used by being combined with an image sensor (not illustrated), such as a solid-state imaging sensor. The image sensor is disposed in the back of the lens holder 40 (the negative side in the Z-axis direction) and photoelectrically converts an emitted light from the lens 100 held by the lens drive device 2 into an image. The image sensor is disposed in any manner. The image sensor may directly be fixed to the fixed unit 4 of the lens drive device 2 or may be connected to the lens drive device 2 via other members.

In the description of the lens drive device 2, the Z-axis is a parallel direction to the optical axis of the lens 100 shown in FIG. 1, and the X-axis and the Y-axis are orthogonal directions to the optical axis.

As shown in FIG. 2 and FIG. 3, the movable unit 3 of the lens drive device 2 is supported to the fixed unit 4 by four suspension wires 16 extending in the optical axis. As shown in FIG. 2, the suspension wires 16 are arranged at four corners of the substantially rectangular lens drive device 2, and four corners of the movable unit 3 and four corners of the fixed unit 4 are connected to each other. The suspension wires 16 are made of an elastic material, such as metal, and at least two suspension wires 16 also function as an electricity supply passage to the focus coil 46 fixed to the lens holder 40.

Incidentally, a support portion for relatively movably connecting the movable unit 3 to the fixed unit 4 is not limited to the suspension wires 16 shown in FIG. 2, but may be another mechanism that relatively movably supports the movable unit 3 in orthogonal directions to the optical axis, such as a rolling ball and a slide mechanism.

As shown in FIG. 2, the ends of the suspension wires 16 on the positive side in the Z-axis direction are fixed to an outer portion of the front spring 90. The front spring 90 includes the outer portion fixable to the frame 60, an inner portion fixable to the lens holder 40, and an arm portion that connects the outer portion and the inner portion. The front spring 90 is divided into multiple pieces and also functions as an electricity supply passage to the focus coil 46 similarly to some of the suspension wires 16.

As shown in FIG. 3, the movable unit 3 includes the frame 60, the magnets 80 fixable to the frame 60, the lens holder 40 relatively movably held to the frame 60 and the magnets 80 in the optical axis, and the focus coil 46 fixable to the lens holder 40. The lens holder 40 and the frame 60 are connected by two springs (the front spring 90 attachable on the positive side in the Z-axis direction and the rear spring 50 attachable on the negative side in the Z-axis direction). As is the case with the front spring 90, the rear spring 50 also includes an inner portion fixable to the lens holder 40 and an arm portion that connects an outer portion and the inner portion.

As shown in FIG. 2 and FIG. 3, the lens holder 40 has a hollow cylindrical shape, and the lens 100 is fixed to an inner circumferential surface of the lens holder 40. As shown in FIG. 3, the ring-shaped focus coil 46 is fixed to an outer circumferential surface of the lens holder 40 and surrounds it. The focus coil 46 faces the inner surfaces of the magnets 80.

As shown in FIG. 2, the frame 60 fixable to the outer portion of the front spring 90 has a substantially rectangular frame shape. The magnet 80 is fixed to each side of the frame 60, and the lens drive device 2 includes four magnets 80. The magnets 80 have a substantially cuboid outer shape and are arranged to surround the lens holder 40.

As shown in FIG. 3, the magnets 80 and the focus coil 46 facing the magnets 80 with a predetermined distance in orthogonal directions to the optical axis form a voice coil motor that drives the lens 100 held by the lens holder 40 in the optical axis.

FIG. 4 is a perspective view illustrating the coil board 30, the base board 20, and their peripheral members contained in the lens drive device 2. As shown in FIG. 4, the coil board 30 is provided with a coil board opening 34 (the optical axis O passes through the central part) and has a substantially rectangular plate outer shape orthogonal to the optical axis O. The ends of the suspension wires 16 on the negative side in the Z-axis direction arc fixed to the four corners of the coil board 30.

The coil board 30 includes the image-stabilizer coils 32 (coils for image-stabilization drive). As shown in FIG. 4, the coil board 30 includes four image-stabilizer coils 32 arranged to surround the coil board opening 34 in the four sides of the coil board 30.

As shown in FIG. 3, the image-stabilizer coils 32 face the magnets 80 of the movable unit 3 with a predetermined distance in the optical axis and drive the magnets 80 in orthogonal directions to the optical axis of the lens 100. Thus, the image-stabilizer coils 32 and the magnets 80 form a voice coil motor that drives the lens 100 held by the lens holder 40 in orthogonal directions to the optical axis.

The coil board 30 includes the coil wiring 31 connected to the image-stabilizer coils 32. As shown in FIG. 10, the coil wiring 31 is partially exposed to the surface of the coil board 30 on the negative side in the Z-axis direction, and the exposed portion is connected to a first conductive portion 71 mentioned below. The image-stabilizer coils 32 and the coil wiring 31 are made of a good metallic conductor. As shown in FIG. 4, the surfaces of the image-stabilizer coils 32 and the coil wiring 31 are covered with a coil board insulation portion (insulator) 35 (see FIG. 10) except for a part of the coil wiring 31 to be connected with the first conductive portion 71.

As shown in FIG. 4, the coil board 30 is provided with through holes for insertion of position sensors 18, each of which detects a position of the magnet 80, and the position sensors 18 fixed to the base board 20 face the magnets 80 via the through holes. Incidentally, in addition to the element connected to the image-stabilizer coil 32, the coil wiring 31 owned by the coil board 30 includes an element electrically connectable to the suspension wires 16. As with the coil wiring 31 connected to the image-stabilizer coils 32, a part of the coil wiring 31 connected to the suspension wires 16 is also exposed to the surface of the coil board 30 on the negative side in the Z-axis direction, and the first conductive portion 71 is connected to the exposed portion.

As shown in FIG. 3 and FIG. 4, the base board 20 is disposed to the coil board 30 on the negative side in the Z-axis direction opposite to the positive side in the Z-axis direction (the coil board 30 faces the magnets 80). As shown in FIG. 5 (a perspective view of the base board 20), the base board 20 is provided with the base opening 22 (an opening where the optical axis O passes through the central part) and includes a coil board facing part 20a and a pair of connector parts 23. The coil board facing part 20a has a substantially rectangular plate outer shape orthogonal to the optical axis O. The pair of connector parts 23 is connected to both sides of the coil board facing part 20a in the Y-axis direction.

As shown in FIG. 3 and FIG. 4, the base opening 22 of the base board 20 is disposed to substantially correspond to the coil board opening 34 of the boil board 30 when viewed from the Z-axis direction. As shown in FIG. 5, the pair of connector parts 23 is foldable to the coil board facing part 20a. The connector parts 23 are connectable to an external board that transmits electric power and control signal for driving the lens drive device 2 to the lens drive device 2.

FIG. 6 is a plane view illustrating the base board 20 and its peripheral members. As shown in FIG. 5 and FIG. 6, the base board 20 includes a plurality of base wirings 21. The base wirings 21 are made of a metallic good conductor and for a conductive passage continuing from one end connected with the first conductive portion 71 in the coil board facing part 20a to the other end exposed at the connector part 23.

As shown in FIG. 9, the base wirings 21 are partially exposed to the surface of the coil board facing part 20a of the base board 20 on the positive side in the Z-axis direction, and the first conductive portions 71 (see FIG. 6) are connected to the exposed portions. Incidentally, FIG. 5, FIG. 6, FIG. 7, and. FIG. 9 illustrate the base wirings 21 by transparentizing a base insulation portion (insulator) 25 (see FIG. 8A) for recognition of arrangement of the base wirings 21 located below the insulator, but the base wirings 21 are actually covered with the base insulation portion 25 except for one end connected to the first conductive portion 71 and the other end exposed at the connector part 23.

As shown in FIG. 5 and FIG. 6, the first conductive portions 71 and resin portions 72 are arranged on the surface of the coil board facing part 20a of the base board 20 on the positive side in the Z-axis direction. As shown in FIG. 8A (a cross-sectional view of the fixed unit 4 in the vicinity of the first conductive portion 71), the first conductive portion 71 conductively connects the coil wiring 31 disposed on the positive side of the first conductive portion 71 in the Z-axis direction and the base wiring 21 disposed on the negative side of the first conductive portion 71 in the Z-axis direction.

As shown in FIG. 8A, the first conductive portion 71 is made of a conductive material, such as solder and conductive adhesive, but may be made of any material that conducts the coil wiring 31 and the base wiring 21. Incidentally, as shown in FIG. 8A, the base board 20 contains a metal plate 24 having the base opening 22 shown in FIG. 6. As shown in FIG. 8A, the base wiring 21 is disposed near the coil board 30 on the plate 24 via the base insulation portion 25, and the plate 24 with conductivity is insulated by the base insulation portion 25.

As shown in FIG. 7 (a partially enlarged view of FIG. 6), the first conductive portions 71 are disposed away from an opening periphery 22a of the base opening 22 to the outside of the base opening 22 in the radial direction and are not exposed to the base opening 22. Moreover, the first conductive portions 71 and the opening periphery 22a are divided by a first resin portion 74. In the fixed unit 4, only some of the first conductive portions 71 may be away from the opening periphery of the base opening 22, but as shown in FIG. 6, all of the first conductive portions 71 are preferably away from the opening periphery 22a of the base opening 22 in view of more effectively preventing particles from flowing into the base opening 22.

As shown in FIG. 6, each of the resin portions 72 includes the first resin portion 74 surrounding the first conductive portion in the optical axis and a second resin portion 76 disposed away from the first resin portion 74. A plurality of resin portions 72 including the first resin portion 74 and the second resin portion 76 is arranged. intermittently around the base opening 22.

As shown in FIG. 8A, the first resin portion 74 connects the coil board 30 and the base board 20 in the Z-axis direction. A part of the first resin portion 74 enters a step between the exposed surface of the coil wiring 31 and the insulation surface of the coil board 30, and another part of the first resin portion 74 enters a step between the exposed surface of the base wiring 21 and the surface of the base insulation portion 25.

As shown in FIG. 8A, the exposed parts of the first conductive portion 71 and the coil wiring 31 and the base wiring 21 connected to the first conductive portion 71 are covered with the first resin portion 74 and the insulators of the boards 20 and 30 and are thereby not exposed. Since the first resin portion 74 covers and protects the first conductive portion 71 and the like, the generation of particles from the connection portion of the first conductive portion 71 is prevented, and dust and water can be prevented from attaching to the conductive portion.

The entire part of the first resin portion 74 has insulation property and is mainly made of a resin, but as shown in FIG. 8C, the first resin portion 74 contains metal particles 74a unevenly distributed in the resin. The first resin portion 74 containing the metal particles 74a have good heat dissipation characteristics. The metal particles 74a contained in the first resin portion 74 are not limited and may be, for example, a conductive material similar to that contained in the first conductive portion 71.

As shown in FIG. 6, the second resin portion 76 is formed into an arc shape along the opening periphery 22a. As shown in FIG. 8A, the second resin portion 76 connects the insulation surface of the coil board 30 and the surface of the base insulation portion 25. The second resin portion 76 is formed by a resin where an adhesive is hardened, but does not need to contain the metal particles 74a contained in the first resin portion 74.

As shown in FIG. 8B, the second resin portion 76 contains a spacer 76a defining a space between the coil board 30 and the base board 20. The spacer 76a is sandwiched by the coil board 30 and the base board 20 and thereby prevents the space between the coil board 30 and the base board 20 from being smaller than a particle size of the spacer 76a. The spacer 76a can be disposed between the coil board 30 and the base board 20 by, for example, being dispersed into an adhesive to be a material of the second resin portion 76. The spacer 76a has any particle size. For example, the spacer 76a can have a particle size that is larger than a particle size of the metal particles 74a contained in the first resin portion 74.

As shown in FIG. 7, the first resin, portions 74 and the second resin portions 76 are arranged away from the opening periphery 22a to the outside in the radial direction and are not exposed to the base opening 22. In view of preventing particles from flowing into the base opening 22, the first resin portions 74 and the second resin portions 76 are also preferably arranged to avoid the opening periphery 22a. When a resin that generates fewer particles is employed for a material of the first resin portions 74 and the second resin portions 76, however, the resin portions 72 may be exposed to the base opening 22.

In the lens drive device 2, as mentioned above, the first conductive portions 71 connecting the coil wiring 31 and the base wiring 21 as shown in FIG. 8A are arranged away from the opening periphery 22a of the base opening 22 to the outside in the radial direction as shown in FIG. 7. Thus, the first conductive portions 71 and other members (e.g., the lens holder 40) are prevented from colliding with each other, and the generation of particles from the first conductive portions 71 can be prevented.

Since the first conductive portions 71 are not exposed to the opening periphery 22a, particles generated from the first conductive portions 71 can be prevented from flowing into the optical passage. Moreover, the first conductive portions 71 are not exposed to the opening and are thereby less subject to receive impacts or so. Thus, the lens drive device 2 is also advantageous in connection reliability compared to prior arts where a conductive portion is exposed to an opening. Moreover, when the base board 20 includes the metallic plate 24, the lens drive device 2 can appropriately secure the insulation between the first conductive portions 71 and the plate 24 by separating the first conductive portions 71 from the opening periphery 22a and arranging the resin portions 72.

Hereinbefore, the lens drive device 2 according to the present invention is described based on an embodiment, but the present invention is not limited to only the above-mentioned embodiment and, needless to say, includes many other embodiments and variations. In the above-mentioned embodiment, for example, the plate 24 of the base board 20 is made of metal and can thereby have a favorably secured strength even if it is thin, but the base board of the present invention is not limited to a base board having the metallic plate 24 and may be a base board having a plate made of resin or other materials.

The arrangement of the resin portions 72 is not limited to the one shown in FIG. 6, and the first resin portions 74 and the second resin portions 76 may have a different shape from the shape shown in the embodiment. FIG. 11 is a plane view illustrating the base board 20 and its peripheral members of a lens drive device with resin portions 172 according to First Variation. In the resin portions 172 according to First Variation, as with the second resin portions 76, first resin portions 174 are formed into an arc shape along the opening periphery 22a.

Each of the first resin portions 174 connects a plurality (two in the example of FIG. 11) of first conductive portions 71 and covers the periphery of the first conductive portions 71. Since each of the first resin portions 174 is formed broadly around the first conductive portions 71, the generation of particles from the first conductive portions 71 is effectively prevented, and the first resin portions 174 can effectively protect the first conductive portions 71. Moreover, the first resin portions 174 have a favorable reinforcement effect on the connection of the boil board 30 and the base board 20. Except for the shape of the first resin portions 174, the lens drive device according to First Variation is similar to the lens drive device 2 according to the embodiment and demonstrates similar effects thereto.

FIG. 12 is a plane view illustrating the base board 20 and its peripheral members of a lens drive device with resin portions 272 according to Second Variation. The resin portions 272 according to Second Variation are arranged continuously to surround the base opening 22.

As shown in FIG. 12, each of the resin portions 272 includes a first resin portion 274 and the second resin portion 76, and as with the second resin portion 76, the first resin portions 274 are formed into an arc shape along the opening periphery 22a. As with the first resin portions 174 shown in FIG. 11, each of the first resin portions 274 connects a plurality of first conductive portions 71 and connects two second resin portions 76 adjacent to each other. Thus, each of the resin portions 272 has a ring shape where the first resin portions 274 and the second resin portions 76 are connected to each other.

The resin portions 272 continuing in such a ring manner can effectively prevent the inflow of particles from the outside into the base opening 22. Except for the shape of the first resin portions 274, the lens drive device according to Second Variation is similar to the lens drive device 2 according to the embodiment and demonstrates similar effects thereto. Incidentally, the resin portions 272 having a ring shape do not necessarily have the shape shown in FIG. 12 (the first resin portions 274 and the second resin portions 76 are connected) and may have a shape where the first resin portion (see FIG. 8C) containing the metal particles 74a is formed into a ring shape, a shape where the second resin portion containing the spacer 76a (see FIG. 8B) is formed into a ring shape, or the like.

DESCRIPTION OF THE REFERENCE NUMERICAL

2 . . . lens drive device

3 . . . movable unit

4 . . . fixed unit

8 . . . case

16 . . . suspension wire

18 . . . position sensor

20 . . . base board

21 . . . base wiring

22 . . . base opening

22a . . . opening periphery

23 . . . connector part

24 . . . plate

25 . . . base insulation portion

30 . . . coil board

31 . . . coil wiring

32 . . . image-stabilizer coil

34 . . . coil board opening

35 . . . coil board insulation portion

40 . . . lens holder

46 . . . focus coil

50 . . . rear spring

60 . . . frame

71 . . . first conductive portion

72 . . . resin portion

74 . . . first resin portion

74a . . . metal particle

76 . . . second resin portion

76a . . . spacer

80 . . . magnet

90 . . . front spring

100 . . . lens

O . . . optical axis