Lens driving apparatus

A lens driving apparatus includes a lens holding member, a static member including a housing, a biasing member, and a moving mechanism. The biasing member includes upper and lower leaf springs. The upper leaf spring includes an upper first portion, an upper second portion, and an upper elastic arm portion. A through hole is formed in the upper first portion of the upper leaf spring. The lens holding member includes a fastening portion that includes a mount surface on which the upper leaf spring is placed, a recess facing the through hole, and a protrusion inserted into the through hole. An adhesive held in the recess surrounds the protrusion and part of the adhesive spreads to an upper surface of the upper first portion of the upper leaf spring through the through hole. The upper leaf spring is fixed to the lens holding member with the adhesive.

CLAIM OF PRIORITY

This application claims benefit of Japanese Patent Application No. 2014-014553 filed on Jan. 29, 2014, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lens driving apparatuses and particularly to a lens driving apparatus in which an upper leaf spring and a lens holding member are bonded together.

2. Description of the Related Art

These days, a large number of portable devices include a function with which still or moving images are taken. Such portable devices include a lens driving apparatus that drives a lens body to automatically focus on a target image during image capturing of a subject. Examples known as a lens driving apparatus used in a portable device include a lens driving apparatus described in Japanese Registered Utility Model No. 3183101.

Referring now toFIG. 20, the lens driving apparatus described in Japanese Registered Utility Model No. 3183101 is described below.FIG. 20is an exploded perspective view of the configuration of a lens driving apparatus900described in Japanese Registered Utility Model No. 3183101.

The lens driving apparatus900described in Japanese Registered Utility Model No. 3183101 includes a lens holding member912that can hold a lens body, biasing members that support the lens holding member912in such a manner as to allow the lens holding member912to move in an optical axis direction, a fastening member911that fastens part of the biasing members, and a moving mechanism910that includes magnets915, a coil913, and a yoke914. The biasing members are constituted by an upper leaf spring916and a lower leaf spring917. The coil913is wound around the lens holding member912. When an electrical current is caused to pass through the coil913disposed in a magnetic field of the magnets915, an electromagnetic force acts on the coil913in a predetermined direction. The electromagnetic force acting on the coil913moves the lens holding member912around which the coil913is wound. Such a movement of the lens holding member912allows a portable device including the lens driving apparatus900to focus on a target image. The lens driving apparatus900holds the lens holding member912in a neutral position in an initial state using the upper leaf spring916and the lower leaf spring917.

In the lens driving apparatus900described in Japanese Registered Utility Model No. 3183101, the upper leaf spring916biases the lens holding member912upward and the lower leaf spring917biases the lens holding member912downward in order to hold the lens holding member912in a neutral position in the initial state. The upper leaf spring916and the lens holding member912are fixed to each other by being bonded together. Thus, when the lens driving apparatus900receives an impact in a case, for example, where it is dropped by mistake, the adhesive used for joining the upper leaf spring916and the lens holding member912together may come off.

SUMMARY OF THE INVENTION

To address the above-described problem, the present invention provides a lens driving apparatus in which an adhesive used for joining an upper leaf spring and a lens holding member together is less likely to come off.

A lens driving apparatus according to an aspect of the present invention includes a tubular lens holding member that is capable of holding a lens body, a static member including a housing that accommodates the lens holding member therein, a biasing member that supports the lens holding member so as to allow the lens holding member to move in an optical axis direction, and a moving mechanism that at least includes a magnet and a coil and moves the lens holding member in the optical axis direction. The biasing member includes an upper leaf spring, fixed to an upper portion of the lens holding member, and a lower leaf spring, fixed to a lower portion of the lens holding member. The upper leaf spring includes a first portion fixed to the lens holding member, a second portion fixed to the static member, and an elastic arm portion positioned between the first portion and the second portion. A through hole is formed in the first portion of the upper leaf spring. The lens holding member includes a fastening portion. The fastening portion includes a mount surface on which the upper leaf spring is placed, an adhesive holding portion that faces the through hole, and a protrusion that protrudes from the adhesive holding portion and is inserted into the through hole. An adhesive held in the adhesive holding portion surrounds the protrusion and part of the adhesive spreads to an upper surface of the first portion of the upper leaf spring through the through hole, so that the upper leaf spring is fixed to the lens holding member with the adhesive.

In this structure, the adhesive held in the adhesive holding portion spreads to an upper surface of the first portion of the upper leaf spring through the through hole. The upper leaf spring can thus be fixed to the lens holding member in such a manner as to be pressed from the upper surface with the adhesive. This structure minimizes the chance of separation of an adhesive between the upper leaf spring and the lens holding member regardless of an impact being exerted on the lens driving apparatus due to a fall or other causes. The fastening portion of the lens holding member includes the protrusion, which is inserted into the through hole. Thus, the protrusion can hold the adhesive surrounding the protrusion, whereby the adhesive easily spreads to a portion on the upper surface of the first portion. This structure thus can provide a lens driving apparatus that minimizes the chance of separation of an adhesive between an upper leaf spring and a lens holding member.

In a lens driving apparatus according to another aspect of the present invention, the adhesive holding portion may be a recess that is recessed with respect to the mount surface and filled with the adhesive, and the adhesive may be disposed over and under a portion of the first portion, so that the upper leaf spring is fixed to the lens holding member.

In this structure, the upper leaf spring is bonded to the lens holding member with the adhesive with which the recess is filled and the adhesive that has spread to the upper surface of the first portion of the upper leaf spring through the through hole. Since the lower surface of the upper leaf spring, the inner surface of the through hole, and the upper surface of the upper leaf spring are held with the adhesive, the upper leaf spring can be more securely fixed to the lens holding member with the adhesive.

In a lens driving apparatus according to another aspect of the present invention, the through hole may be noncircular.

Compared to a circular through hole, the noncircular through hole can increase an area over which the adhesive spreads to bond the upper leaf spring to the lens holding member. The noncircular through hole thus can more firmly bond and fix the upper leaf spring to the lens holding member.

In a lens driving apparatus according to another aspect of the present invention, the lens holding member may include a rising base portion that includes the fastening portion. A boundary between the first portion and the elastic arm portion of the upper leaf spring may be located at a position corresponding to an outer periphery of the base portion.

In this structure, the boundary between the first portion and the elastic arm portion of the upper leaf spring is located at a position corresponding to the outer periphery of the base portion. This structure is thus more likely to prevent the elastic arm portion from coming into contact with the base portion when the elastic arm portion is in operation, thereby loosening the restriction on the operation of the elastic arm portion. Thus, the upper elastic arm portion can become fully operable. This structure enables production of the biasing force that varies to a lesser extent and can provide a lens driving apparatus that operates stably.

In a lens driving apparatus according to another aspect of the present invention, the recess may include an extension portion that extends toward the elastic arm portion and the through hole may include a fringe portion that faces the extension portion. The adhesive with which the extension portion is filled may be disposed over and under a portion of the first portion extending along the fringe portion.

In this structure, the recess includes the extension portion and the through hole includes the fringe portion that faces the extension portion. When the fringe portion of the through hole is disposed so as to overlap part of the extension portion filled with the adhesive, the adhesive squeezed by the first portion located near the fringe portion easily flows out to the upper surface of the first portion including the fringe portion. In addition, the provision of the fringe portion facing the extension portion can increase the area over which the adhesive spreads to bond the upper leaf spring to the lens holding member. Specifically, the first portion can increase an area over which the adhesive spreads to bond the upper leaf spring to the lens holding member and the upper surface and the lower surface of the first portion are held with the adhesive. Thus, the end portion of the first portion can be securely joined to the fastening portion of the lens holding member and thus the base portion of the elastic arm portion is fixed. This structure prevents the first portion from rising in accordance with the operation of the upper elastic arm portion, whereby the biasing force can be prevented from varying due to the rise of the first portion. This structure thus enables production of a biasing force that varies to a lesser extent and can provide a lens driving apparatus that operates more stably.

In a lens driving apparatus according to another aspect of the present invention, in an initial state where an electrical current is not caused to pass through the coil, the upper leaf spring may bias the lens holding member upward whereas the lower leaf spring may bias the lens holding member downward.

In this structure, in the initial state, the lens holding member is held at a position at which the biasing force of the upper leaf spring and the biasing force of the lower leaf spring are in balance. Since the lens holding member is held in this manner, the lens holding member is movable in positive and negative optical axis directions from the position at which the lens holding member is held in the initial state. Thus, when images are taken using an electronic device including the lens driving apparatus, the device can focus on a subject by moving the lens holding member by a minimum amount from the position at which it is held in the initial state.

The present invention can provide a lens driving apparatus in which an adhesive used for joining an upper leaf spring and a lens holding member together is less likely to come off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A lens driving apparatus100according to a first embodiment is described below.

Referring toFIG. 1toFIG. 9first, a configuration of the lens driving apparatus100according to the embodiment is described.FIG. 1is an exploded perspective view of the configuration of the lens driving apparatus100according to the first embodiment.FIGS. 2A and 2Billustrate an appearance of the lens driving apparatus100according to the first embodiment, whereFIG. 2Ais a perspective view of the appearance of the lens driving apparatus100andFIG. 2Bis a plan view of the lens driving apparatus100when viewed from the Z1 side illustrated inFIG. 2A.FIGS. 3A and 3Billustrate a lens holding member1according to the first embodiment, whereFIG. 3Ais a perspective view of the appearance of the lens holding member1andFIG. 3Bis a perspective view of the appearance of the lens holding member1when viewed from the Z2 side inFIG. 3A.FIGS. 4A and 4Billustrate a portion IVA illustrated inFIG. 3A, whereFIG. 4Ais an enlarged perspective view of the portion IVA illustrated inFIG. 3AandFIG. 4Bis a plan view of the portion IVA when viewed from the Z1 side illustrated inFIG. 4A.FIGS. 5A to 5Cillustrate a coil4according to the first embodiment in the state of being held by the lens holding member1, whereFIG. 5Ais a perspective view of the coil4in the state of being held by the lens holding member1,FIG. 5Bis a perspective view of the coil4in the state of being held by the lens holding member1when viewed from the Z2 side illustrated inFIG. 5A,FIG. 5Cis an enlarged perspective view of a portion VC illustrated inFIG. 5B.FIGS. 6A and 6Billustrate an upper leaf spring5according to the first embodiment, whereFIG. 6Ais a perspective view of an appearance of the upper leaf spring5andFIG. 6Bis an enlarged plan view of a portion VIB illustrated inFIG. 6Awhen viewed from the Z1 side.FIGS. 7A and 7Billustrate a lower leaf spring6according to the first embodiment, whereFIG. 7Ais a perspective view of an appearance of the lower leaf spring6andFIG. 7Bis a plan view of the lower leaf spring6when viewed from the Z1 side illustrated inFIG. 7A.FIGS. 8A and 8Billustrate a housing7according to the first embodiment, whereFIG. 8Ais a perspective view of an appearance of the housing7andFIG. 8Bis a plan view of the housing7when viewed from the Z2 side illustrated inFIG. 8A.FIG. 9is a perspective view of an appearance of a base member8according to the first embodiment.

As illustrated inFIG. 1, the lens driving apparatus100includes a lens holding member1, a static member2including a housing7and a base member8, a moving mechanism50including at least magnets3and a coil4, and a biasing member30including an upper leaf spring5and lower leaf springs6. As illustrated inFIGS. 2A and 2B, the lens driving apparatus100has a substantially rectangular parallelepiped shape. The lens driving apparatus100is capable of moving the lens holding member1in an optical axis direction LD (Z1 and Z2 directions).

The lens holding member1is made of synthetic resin and formed in a tubular shape so as to be capable of holding a lens body, as illustrated inFIGS. 3A and 3B. The lens holding member1has a tubular portion1hhaving a tubular shape. The tubular portion1hhas both ends open and has a hollow opening1g. On an inner circumferential wall of the opening1g, a screw thread is formed so as to hold the lens body. On an outer circumferential surface of the tubular portion1h, coil holding units1qthat protrude outward are disposed at equal intervals at four positions. In this embodiment, the coil holding units1qare disposed on the X1 and X2 sides and Y1 and Y2 sides of the tubular portion1h. On a first end side (Z1 side) of the tubular portion1h, upper leaf spring receiving portions1kthat extend in directions away from the outer circumferential surface at the end portion are formed. The upper leaf spring receiving portions1kare disposed at opposing positions across the opening1g. In this embodiment, upper leaf spring receiving portions1kare disposed on the X1 and X2 sides, one at each side, so as to be continuous with the corresponding coil holding units1q.

As illustrated inFIGS. 4A and 4B, a base portion1eis formed on an upper surface of each upper leaf spring receiving portion1kso as to protrude upward (Z1 direction) and the base portion1eincludes a fastening portion1d. The fastening portion1dincludes a mount surface1a, which is an upper surface having a flat shape, recesses1brecessed with respect to the mount surface1a, and protrusions1cthat protrude from the recesses1band have a columnar shape. Each recess1bserves as an adhesive holding portion that faces a through hole5fof the upper leaf spring5, which is described below. The recess1bformed on the Y1 side has an extension portion1fthat is recessed and extends in the Y1 direction. The recess1bformed on the Y2 side has an extension portion1fthat is recessed and extends in the Y2 direction. The fastening portion1dhas a rectangular parallelepiped stopper protrusion1rprotruding upward at a position between the recesses1bon the mount surface1a.

As illustrated inFIGS. 3A and 3B, the lens holding member1has a flange portion1m, which expands in a direction away from the outer circumferential surface of the end portion on a second end side (Z2 side) of the tubular portion1h. The flange portion1mis disposed around almost the entire circumference of the tubular portion1h. On the end surface of the second end side of the tubular portion1hincluding the flange portion1m, lower holding protrusions1nand coil-wound protrusions1pare disposed. The lower holding protrusions1nhave a columnar shape and protrude in the optical axis direction LD (in the Z2 direction). The lower holding protrusions1nare provided at two positions on each side (each of Y1 and Y2 sides inFIG. 3B) so as to face the corresponding lower holding protrusions1nacross the opening1g. The coil-wound protrusions1phave a rectangular parallelepiped shape and protrude in the optical axis direction LD (in the Z2 direction). The coil-wound protrusions1pare disposed at opposing positions across the opening1g(one on each of X1 and X2 sides inFIGS. 3A and 3B).

The coil4is made of a metal wire having electric conductivity. As illustrated inFIG. 1, the coil4includes a wound coil portion4aand end portions4b. The wound coil portion4ais formed so as to be wound around the outer circumference of the tube. Both end portions4bof the metal wire extend from the wound coil portion4a. The surface of the portion of the metal wire forming the wound coil portion4ais coated with a nonconductive material. Turns of the wound coil portion4aare insulated with one another at the surface of the metal wire. When an electrical current is caused to pass through the coil4, the electrical current circularly flows through the metal wire.

In this embodiment, as illustrated inFIGS. 5A to 5C, the coil4is formed by winding a metal wire around the coil holding units1qof the lens holding member1. Specifically, the wound coil portion4ais formed by winding a metal wire around the outer circumference of the lens holding member1. When the wound coil portion4ais viewed from above (the Z1 side), the wound coil portion4ais formed in a shape of an octagon in which short sides having a first length L1and long sides having a second length L2longer than the first length L1are alternately connected together. The portions of the wound coil portion4acorresponding to the long sides are in contact with the coil holding units1qand the portions of the wound coil portion4acorresponding to the short sides are spaced apart from the tubular portion1h. End portions4bof the coil4are wound around and held at the coil-wound protrusions1pof the lens holding member1. In order to prevent the wound metal wire from being unwound, the ends of the end portions4bof the coil4wound around and held at the coil-wound protrusions1pare subjected to an appropriate fastening measure, such as by being bonded to the coil-wound protrusions1pusing an adhesive or the like or sealed in resin. Alternatively, at the beginning of winding, one end of the end portion4bmay be arranged along and brought into contact with the coil-wound protrusion1pand the remaining portion of the coil may be wound around the end and the coil-wound protrusion1pso that the end is held in place. The end portions4bof the coil4wound around the coil-wound protrusions1pextend from base portions of the coil-wound protrusions1pso as to be continuous with the wound coil portion4a.

As illustrated inFIG. 1, the biasing member30includes an upper leaf spring5and a lower leaf spring6. The upper leaf spring5is made of sheet metal. As illustrated inFIGS. 6A and 6B, the upper leaf spring5includes upper first portions5a(first portions), an upper second portion5b(second portion), and upper elastic arm portions5c(elastic arm portions) each positioned between the corresponding upper first portion5aand the upper second portion5b. The upper second portion5bis disposed outside the upper first portions5a. The upper first portions5aeach have a substantially rectangular base portion5d. The base portion5dof each upper first portion5ahas through holes5fon both sides (Y1 and Y2 sides) and an indentation5gat a position between the through holes5f. The distance between the through holes5fis substantially the same as the distance between the protrusions1cof the lens holding member1and the through holes5fare sized so as to be capable of receiving the protrusions1c. The through holes5fhave a noncircular shape having recesses and protrusions. In this embodiment, the through holes5fhave fringe portions5eat the portions E illustrated inFIG. 6B. Each indentation5gis a cut sized so as to be capable of receiving the corresponding stopper protrusion1r. The upper first portions5aare spaced apart from each other at a distance equivalent to the diameter of the opening1gof the lens holding member1and disposed at opposite positions while having their indentations5gfacing away from each other. The upper second portion5bhas an annular shape having a rectangular contour. The upper second portion5bincludes substantially triangular fastening portions5h, which expand to the inner side of the rectangular, at four corner portions of the rectangular. Each upper elastic arm portion5chas a corrugated line shape and connects the upper first portion5ato the adjacent fastening portion5hof the upper second portion5b. The upper elastic arm portions5chave elasticity. For example, while the upper second portion5bis fixed, upper first portions5aare vertically movable by bending the upper elastic arm portions5c.

The lower leaf springs6are made of sheet metal. As illustrated inFIGS. 7A and 7B, the lower leaf springs6include a first member6A and a second member6B, which are symmetrical with respect to a line. The lower leaf springs6form annular shape having a rectangular contour when the first member6A and the second member6B are arranged side by side. The lower leaf springs6are described below without the first member6A and the second member6B being distinguished from each other, unless otherwise noted, on the assumption that both of the first member6A and the second member6B have the components described below.

Each lower leaf spring6has a lower first portion6a, a lower second portion6b, and lower elastic arm portions6ceach positioned between the lower first portion6aand the lower second portion6b. The first member6A and the second member6B are disposed so that the lower first portions6aface each other and the lower second portions6bare disposed outward from the lower first portions6a. The lower first portions6ahave an arc shape. Each lower first portion6aincludes a rectangular-plate-shaped first holding unit6dat a middle portion and substantially triangular-plate-shaped second holding units6eat both end portions.

The first holding unit6dand the second holding units6eare connected together with portions having a curved line shape. Each of the second holding units6ehas a first holding hole6fthrough which the corresponding lower holding protrusion1nof the lens holding member1can be inserted. The lower second portion6bhas a linear shape and includes flat third holding units6gon both ends. The third holding units6gare connected together with a rail portion6h. Each third holding unit6ghas a second holding hole6k, which is a through hole. Here, the second holding hole6kformed at a first end side (Y2 side) is circular, whereas the second holding hole6kformed at a second end side (Y1 side) is noncircular (substantially hexagonal).

The lower elastic arm portions6chave a corrugated line shape and each connect the adjacent second holding unit6eof the lower first portion6ato the adjacent third holding unit6gof the lower second portion6b. The lower elastic arm portion6cdisposed at the first end side is spaced apart from the first holding unit6dat such a distance as to allow the coil-wound protrusion1pof the lens holding member1to be inserted through the space between the lower elastic arm portion6cand the first holding unit6d.

The first member6A and the second member6B having the above described structure are disposed so that their second holding units6eface each other and so that their lower first portions6aform a circle having a diameter substantially the same as the diameter of the tubular portion1hof the lens holding member1. The distance by which each first holding hole6fof the first member6A and the corresponding first holding hole6fof the second member6B are spaced apart from each other is the same as the distance by which the lower holding protrusions1nof the lens holding member1on the Y1 or Y2 side are spaced apart from each other. The lower elastic arm portions6chave elasticity. For example, while the lower second portions6bare fixed, the lower first portion6ais vertically movable by bending the lower elastic arm portions6c.

As illustrated inFIG. 1, the static member2includes a base member8and a housing7. The housing7is made of a metal plate having magnetism. As illustrated inFIG. 8A, the housing7is formed in a hollow, substantially rectangular parallelepiped shape and has an open bottom. The housing7includes an annular outer wall portions7a, four inner wall portions7bdisposed inside the outer wall portions7a, and a top portion7cthat connects the outer wall portions7aand the inner wall portions7btogether in such a manner that the outer wall portions7aand the inner wall portions7bare spaced apart from one another. The outer wall portions7aand the inner wall portions7bextend in the same direction (Z2 direction) so as to be perpendicular to the top portion7c. The outer wall portions7aon four sides cross one another. Corner portions7dare formed at the portions at which the outer wall portions7across one another. The inner wall portions7bare disposed inside the outer wall portions7aso as to face the corner portions7d. When the inner wall portions7bare viewed from the Z1 or Z2 side, the inner wall portions7bhave such a curved shape as to be convex toward the corresponding corner portions7dand are disposed so as to form an arc shape. The inner wall portions7bare formed by performing metalworking on portions of the top portion7c.

When viewed in a plan, a through hole portion7eis defined by the inner wall portions7b, forming the arc shape, at the center of the top portion7c. The through hole portion7ehas such a diameter as to allow the tubular portion1hof the lens holding member1to be inserted therethrough and the diameter of the arc shape formed by the inner wall portions7bis smaller than a dimension (distance between opposing short sides) of the wound coil portion4aof the coil4. In addition, at opposite positions across the through hole portion7e, opposing in the X1 and X2 directions in this embodiment, indentations7gare formed so as to be continuous with the through hole portions7e. Two indentations7gare formed side by side on each side. At four corner portions of the top portion7c, protrusions7fformed by metalworking so as to protrude downward are disposed. Outermost ends of the protrusions7fare disposed on the same level plane so as to be parallel to the top portion7c.

The base member8is made of a synthetic resin material. As illustrated inFIG. 9, when viewed in a plan from below (Z2 side), the base member8has a rectangular contour and has an annular shape having an open hole8a, which is a circular through hole, at the center. The base member8has flat mount portions8c, which are disposed at four corners on the upper surface, and mount protrusions8b, which are disposed on the mount portions8cand protrude in the Z1 direction. The mount protrusions8bare so sized as to be insertable into the second holding holes6kof the lower leaf springs6and so positioned as to correspond to the positions of the second holding holes6k.

A metal member9made of a metal plate is embedded in the base member8while being partially exposed to the outside. A first connection surface portion9aand a second connection surface portion9b, which are portions of the metal member9, are exposed through the mount portions8cof the base member8disposed on a second side (Y2 side). The first connection surface portion9ais exposed through the mount portion8con the X1 side, whereas the second connection surface portion9bis exposed through the mount portion8con the X2 side. The first connection surface portion9aand the second connection surface portion9bare insulated from each other.

At an end portion of the bottom surface of the base member8on the second side (Y2 side), a first connection terminal portion9cand a second connection terminal portion9d, which are portions of the metal member9, protrude downward. The first connection terminal portion9cprotrudes from the bottom surface at a portion on the X1 side whereas the second connection terminal portion9dprotrudes from the bottom surface at a portion on the X2 side. The first connection surface portion9aand the first connection terminal portion9care electrically connected to each other whereas the second connection surface portion9band the second connection terminal portion9dare electrically connected to each other.

From the four corner portions of the base member8, holding portions9e, which are portions of the metal member9, are exposed. The holding portions9eare insulated from the first connection surface portion9aand the second connection surface portion9b.

The magnets3are formed so as to be capable of being placed in spaces defined by the inner wall portions7bof the housing7, the corner portions7dof the housing7, and the outer wall portions7aof the housing7continuous with the corner portions7d. As illustrated inFIG. 1, when the magnets3are viewed in a plan from the Z1 side, each magnet3is formed in a substantially trapezoidal prism having lateral sides with the equal length. Here, the surface corresponding to the short side of the trapezoid is referred to as a first face3a, the surfaces corresponding to the lateral sides are referred to as second faces3b, and the surface corresponding to the long side is referred to as a third face3c. The first face3ais formed in such a shape as to correspond to the shape of the inner surface of each corner portion7dof the housing7. The second faces3bare formed in such a shape as to correspond to the shape of the inner surfaces of the outer wall portions7a. The third face3chas a length corresponding to the length of the long side of a trapezoid that is shorter than the first length L1(seeFIG. 5A).

Referring now toFIGS. 2A and 2B,FIGS. 5A to 5C, andFIGS. 10 to 16, a configuration of the lens driving apparatus100is described.FIG. 10is a schematic cross-sectional view of the lens driving apparatus100taken along the line X-X, XVIII-XVIII, XIX-XIX inFIG. 2B.FIGS. 11A and 11Billustrate the lens holding member1and the lower leaf springs6according to the first embodiment in the state of being fixed to each other, whereFIG. 11Ais a plan view of the lens holding member1and the lower leaf springs6in the state of being fixed to each other andFIG. 11Bis a schematic side view of a portion XIB illustrated inFIG. 11Awhen viewed from the X1 side.FIG. 12is a plan view of the lower leaf springs6and the base member8according to the first embodiment in the state of being connected together.FIG. 13is a schematic cross-sectional view of the lens driving apparatus100taken along the line XIII-XIII illustrated inFIG. 2B.FIGS. 14A and 14Billustrate an upper first portion5aplaced on a mount surface1aaccording to the first embodiment, whereFIG. 14Ais a plan view of the upper first portion5aplaced on the mount surface1aandFIG. 14Bis a side view of the upper first portion5aplaced on the mount surface1awhen viewed from the X1 side illustrated inFIG. 14A.FIGS. 15A and 15Billustrate the upper first portion5aaccording to the first embodiment in the state of being joined to the mount surface1a, whereFIG. 15Ais a perspective view of the upper first portion5ain the state of being joined to the mount surface1aandFIG. 15Bis a plan view of the upper first portion5ajoined to the mount surface1awhen viewed from the Z1 side illustrated inFIG. 15A.FIG. 16is a cross-sectional view of the lens driving apparatus100taken along the line XVI-XVI illustrated inFIG. 15B.

As illustrated inFIGS. 5A to 5C, the coil4is wound around the tubular portion1hof the lens holding member1to form a wound coil portion4a. The end portions4bof the coil4are wound around and held at the coil-wound protrusions1p. As illustrated inFIG. 10, the lower leaf springs6are fixed at the bottom portions (Z2 side) of the flange portions1mof the lens holding member1. At this time, as illustrated inFIG. 11A, the lower holding protrusions1nof the lens holding member1are inserted into the first holding holes6fof the lower leaf spring6and then the lower holding protrusions1nare caulked. Also at this time, the coil-wound protrusions1paround which the end portions4bof the coil4are wound are slightly spaced apart from the lower first portions6aand disposed on the Y2 side of the lower first portions6ainFIG. 11B. The end portions4bof the coil4wound around the coil-wound protrusions1pare fixed to the lower first portions6awith solder SD.

Thus, each of the first member6A and the second member6B of the lower leaf springs6is fixed to the lens holding member1at three positions. As illustrated inFIG. 10, the base member8is disposed below the lower leaf springs6and connected to the lower leaf springs6. Here, as illustrated inFIG. 12, the lower leaf springs6are placed on the mount portions8cof the base member8and the mount protrusions8bof the base member8are inserted into the corresponding second holding holes6k. Then, the mount protrusions8binserted into the second holding holes6kare caulked, whereby the lower second portions6bof the lower leaf springs6and the base member8are connected together. When the lower leaf springs6are placed on the mount portions8c, the lower leaf springs6come into contact with the first connection surface portion9aand the second connection surface portion9band are then fixed by a weld WP.

When the base member8is fixed so as to be stationary, the lens holding member1thus connected to the base member8with the lower leaf springs6interposed therebetween is biased downward by the biasing force of the lower leaf springs6and supported so as to be movable in the optical axis direction LD (Z1 and Z2 directions) illustrated inFIG. 10. In this structure, the first connection terminal portion9c(seeFIG. 9) and the second connection terminal portion9d(seeFIG. 9) are electrically connected to each other via the coil4and the lower leaf springs6.

As illustrated inFIG. 13, the upper leaf spring5is disposed inside the housing7. At this time, the upper leaf spring5is held in a space between the outer wall portions7a(seeFIGS. 8A and 8B) and the inner wall portions7bof the housing7in such a manner that the upper second portion5bcomes into contact with the protrusions7f(seeFIGS. 8A and 8B) disposed on the top portion7c. The magnets3are each placed on the inner side of the corresponding one of the four corner portions7dof the housing7in the state where the first face3a(seeFIG. 1) is being in contact with the corresponding corner portion7dof the housing7and the second faces3b(seeFIG. 1) are being in contact with the corresponding outer wall portions7acontinuous with the corner portion7don both sides. The magnets3are joined and fixed to the housing7while tightly holding the fastening portions5hof the upper leaf spring5together with the top portion7c(protrusions7f) of the housing7. Thus, the upper second portion5bof the upper leaf spring5is fixed to the housing7, which is included in the static member2.

The housing7to which the magnets3and the upper leaf spring5have thus been fixed is stacked on the base member8so as to hold the lens holding member1therein. At this time, the inner wall portions7bof the housing7are inserted into the space between the coil4and the tubular portion1hof the lens holding member1and the coil4is inserted between the inner wall portions7band the magnets3. Here, the tubular portion1h, the inner wall portion7b, the coil4, and the magnet3, which are adjacent to one another, are spaced apart from one another. Such an arrangement of the inner wall portions7b, the coil4, and the magnets3forms a moving mechanism50according to this embodiment that includes the housing7, serving as a yoke, the magnets3, and the coil4.

As illustrated inFIG. 10, the upper leaf spring5is fixed to upper portions of the lens holding member1in the following manner. The upper first portions5aare placed on and fixed by bonding, using a ultraviolet curing adhesive, to the mount surfaces1a(fastening portions1d, seeFIGS. 4A and 4B), disposed at opposing positions across the opening1gof the lens holding member1so as to correspond to the upper first portions5a. The upper leaf spring5thus fixed to the lens holding member1biases the lens holding member1upward.

The following describes bonding between each mount surface1aand the corresponding upper first portion5a. As illustrated inFIGS. 14A and 14B, the upper first portion5ais placed on the mount surface1ain such a manner that the protrusions1care inserted into the through holes5fand the through holes5fface the recesses1b, which are adhesive holding portions. When the upper first portion5ais placed in this manner, each extension portion1fextends toward the corresponding upper elastic arm portion5cand each fringe portion5eis disposed so as to face the corresponding extension portion1f. The boundary (indicated with broken lines inFIG. 14B) between the upper first portion5aand the upper elastic arm portion5cof the upper leaf spring5is located at a position corresponding to the outer periphery of the base portion1e.

When the upper first portion5ais actually placed, the recesses1bare filled with an adhesive GL, which is an ultraviolet curing adhesive, as illustrated inFIGS. 15A and 15Baround the protrusions1c. When the upper first portion5ais placed on the mount surface1awhile the recesses1bare thus filled with the adhesive GL, the upper first portion5ais bonded to the mount surface1awhile the protrusions1c(seeFIGS. 14A and 14B) are covered with the adhesive GL, as illustrated inFIGS. 15A and 15B.

Specifically, as illustrated inFIG. 16, the adhesive GL inserted in the recess1bis provided around the protrusion1cand part of the adhesive GL spreads to a portion on the upper surface of the upper first portion5aof the upper leaf spring5through the through hole5f. When the adhesive GL thus positioned receives ultraviolet rays, the adhesive GL cures, and the curing of the adhesive GL fixes the upper leaf spring5to the lens holding member1. At the same time, the adhesive GL that has entered the extension portion1f, which is part of the recess1b, covers portions on the upper and lower surfaces of the upper first portion5aextending along the fringe portion5e.

In this manner, the lower surface of the upper first portion5ais bonded with the adhesive GL to the mount surface1a(fastening portion1d, seeFIGS. 4A and 4B) of the lens holding member1and the upper surface of the upper first portion5ais also held with the adhesive GL. The adhesive GL with which the upper first portion5ais thus bonded to the mount surface1a(fastening portion1d, seeFIGS. 4A and 4B) of the lens holding member1is disposed at portions that are open upward through the indentations7g, as illustrated inFIGS. 2A and 2B. Thus, ultraviolet rays are applied to the adhesive GL through the indentation7g.

The lens driving apparatus100is formed in this manner.

Referring now toFIG. 10,FIG. 13,FIG. 17toFIG. 19, an operation of the lens driving apparatus100is described.FIG. 17is a schematic view of the positional relationship between the inner wall portion7b, the coil4, and the magnet3when a portion XVII illustrated inFIG. 13is viewed from the Z1 side.FIG. 18is a schematic cross-sectional view of the lens driving apparatus100taken along the line X-X, XVIII-XVIII, XIX-XIX inFIG. 2Bin the state where the lens holding member1according to the first embodiment has been moved upward.FIG. 19is a schematic cross-sectional view of the lens driving apparatus100taken along the line X-X, XVIII-XVIII, XIX-XIX inFIG. 2Bin the state where the lens holding member1according to the first embodiment has been moved downward. InFIG. 18andFIG. 19, the lens holding member1, the coil4, the upper leaf spring5, and the lower leaf springs6in the initial state are indicated by broken lines.

In the lens driving apparatus100, the upper leaf spring5biases the lens holding member1upward and the lower leaf springs6bias the lens holding member1downward. Thus, in the state where the lens driving apparatus100is not provided with electricity, that is, in the initial state where an electrical current is not caused to pass through the coil4, the lens holding member1is positioned at a position at which the biasing force of the lower leaf springs6biasing the lens holding member1downward and the biasing force of the upper leaf spring5biasing the lens holding member1upward are in balance, as illustrated inFIG. 10. Here, the lens holding member1is vertically movable (in the Z1 and Z2 directions) against the biasing force of the lower leaf springs6and the biasing force of the upper leaf spring5. Specifically, the biasing member30supports the lens holding member1in such a manner that the lens holding member1is movable in the optical axis direction LD.

As illustrated inFIG. 13andFIG. 17, the moving mechanism50includes the inner wall portions7b, the magnets3, and the coil4and moves the lens holding member1in the optical axis direction LD. In the moving mechanism50, one inner wall portion7b, the coil4, and the corresponding magnet3are arranged in this order on the same straight line. The electricity can be applied to the lens driving apparatus100through the first connection terminal portion9c(seeFIG. 9) and the second connection terminal portion9d(seeFIG. 9). After the electricity is applied to the lens driving apparatus100, an electrical current flows through the coil4. The direction of the magnetic field of the magnet3is defined as the direction of arrow M illustrated inFIG. 17. In the moving mechanism50, the magnets3and the coil4are disposed so as to face each other. Specifically, since the coil4is disposed in the magnetic field of the magnets3, a Lorentz force is exerted on the coil4when an electrical current flows through the coil4.

After the electricity is applied to the lens driving apparatus100and an electrical current flows in the direction of, for example, arrow K illustrated inFIG. 17, a Lorentz force in the Z1 direction illustrated inFIG. 13is exerted on the coil4, whereby the lens holding member1integrated with the coil4moves upward (in the Z1 direction) against the biasing force of the lower leaf springs6, as illustrated inFIG. 18.

When an electrical current flows in the direction of arrow L illustrated inFIG. 17, a Lorentz force in the Z2 direction illustrated inFIG. 13is exerted on the coil4, whereby the lens holding member1moves downward (in the Z2 direction) against the biasing force of the upper leaf spring5, as illustrated inFIG. 19.

In this manner, by changing the direction of electrical currents flowing through the coil4, the lens holding member1can be operated in the optical axis direction LD. In the actual operation, a lens body, not illustrated, is fixed in the opening1g, whereby the lens holding member1can be operated integrally with the lens body.

Effects of this embodiment are described below.

The lens driving apparatus100according to the embodiment includes a tubular lens holding member1that is capable of holding a lens body, a static member2including a housing7that accommodates the lens holding member1therein, a biasing member30that supports the lens holding member1so as to allow the lens holding member1to move in an optical axis direction, and a moving mechanism50that at least includes a magnet3and a coil4and moves the lens holding member1in the optical axis direction. The biasing member30includes an upper leaf spring5, fixed to an upper portion of the lens holding member1, and a lower leaf spring6, fixed to a lower portion of the lens holding member1. The upper leaf spring5includes a first portion (upper first portion)5afixed to the lens holding member1, a second portion (upper second portion)5bfixed to the static member2, and an upper elastic arm portion5cpositioned between the upper first portion5aand the upper second portion5b. A through hole5fis formed in the upper first portion5aof the upper leaf spring5. The lens holding member1includes a fastening portion1d. The fastening portion1dincludes a mount surface1aon which the upper leaf spring5is placed, a recess1bthat faces the through hole5fand serves as an adhesive holding portion, and a protrusion1cthat protrudes from the recess1band is inserted into the through hole5f. An adhesive GL held in the recess1bsurrounds the protrusion1cand part of the adhesive GL spreads to an upper surface of the upper first portion5aof the upper leaf spring5through the through hole5f. The upper leaf spring5is fixed to the lens holding member1with the adhesive GL.

In this structure, the adhesive GL held in the recess1b, serving as an adhesive holding portion, spreads to an upper surface of the upper first portion5aof the upper leaf spring5through the through hole5f. The upper leaf spring5can thus be fixed to the lens holding member1in such a manner as to be pressed from the upper surface with the adhesive GL. This structure minimizes the chance of separation of an adhesive between the upper leaf spring5and the lens holding member1regardless of an impact being exerted on the lens driving apparatus due to a fall or other causes. The fastening portion1dof the lens holding member1includes the protrusion1c, which is inserted into the through hole5f. Thus, the protrusion1ccan hold the adhesive GL surrounding the protrusion1c, whereby the adhesive GL easily spreads to a portion on the upper surface of the upper first portion5a. This structure is thus effective in providing a lens driving apparatus that minimizes the chance of separation of an adhesive between an upper leaf spring and a lens holding member.

In the lens driving apparatus100according to the embodiment, bonding between each upper first portion5aof the upper leaf spring5and the corresponding fastening portion1dof the lens holding member1is performed in the state where the protrusions1care inserted into the through holes5f. Thus, the adhesive GL easily moves along the protrusions1cto spread to the upper surface of the upper first portion5a.

In the lens driving apparatus100according to the embodiment, the adhesive holding portion is a recess1bthat is recessed with respect to the mount surface1a. Part of the adhesive GL inserted into the recess1bspreads to an upper surface of a portion of the upper first portion5a(for example, a portion near the fringe portion5e) and a lower surface of a portion of the upper first portion5a, so that the upper leaf spring5is fixed to the lens holding member1.

In this structure, the upper leaf spring5is bonded to the lens holding member1with part of the adhesive GL inserted in the recess1band part of the adhesive GL that has spread to the upper surface of the upper first portion5aof the upper leaf spring5through the through hole5f. Since the lower surface of the upper leaf spring5, the inner surface of the through hole5f, and the upper surface of the upper leaf spring5are held with the adhesive GL, the upper leaf spring5can be securely fixed to the lens holding member1with the adhesive. This structure is thus effective in providing a lens driving apparatus that minimizes the chance of separation of an adhesive between an upper leaf spring and a lens holding member regardless of an impact being exerted on the lens driving apparatus due to a fall or other causes.

In the lens driving apparatus100according to the embodiment, the through hole5fis noncircular.

Compared to a circular through hole, the noncircular through hole5fcan increase an area over which the adhesive GL spreads to join the upper leaf spring5to the lens holding member1. The noncircular through hole5fthus can more firmly bond and fix the upper leaf spring5to the lens holding member1.

In the lens driving apparatus100according to the embodiment, the through hole5fhas such a shape that a portion of the through hole5fprotrudes toward the inside of the opening of the through hole5f. In the through hole5fhaving such an opening shaped as above, when the portion protruding toward the inside of the opening (protrusion, below) is placed over the adhesive GL, part of the adhesive GL squeezed by the protrusion flows out from the sides of the protrusion toward the upper side of the protrusion, whereby the protrusion is easily covered with the adhesive GL. This structure thus increases the area over which the adhesive GL spreads to bond the upper leaf spring5to the lens holding member1. Moreover, the existence of the adhesive GL that has spread to the upper surface of the upper first portion5aof the upper leaf spring5through the through hole5ffacilitates joining the upper leaf spring5and the lens holding member1together in the state where the protrusion is being covered with the adhesive GL. Thus, the upper leaf spring5can be more firmly joined and fixed to the lens holding member1.

In the lens driving apparatus100according to the embodiment, the lens holding member1includes a rising base portion1ethat includes the fastening portion1d. A boundary between the upper first portion5aand the upper elastic arm portion5cof the upper leaf spring5is located at a position corresponding to an outer periphery of the base portion1e.

In this structure, the boundary between the upper first portion5aand the upper elastic arm portion5cof the upper leaf spring5is located at a position corresponding to the outer periphery of the base portion1e. This structure is more likely to prevent the upper elastic arm portion5cfrom coming into contact with the base portion1ewhen the upper elastic arm portion5cis in operation, whereby the restriction on the operation of the upper elastic arm portion5cis minimized. Thus, the upper elastic arm portion5ccan become fully operable. This structure thus enables production of the biasing force that varies to a lesser extent and is thus effective in providing a lens driving apparatus that operates stably.

In the lens driving apparatus100according to the embodiment, each recess1bincludes an extension portion1fthat extends toward the corresponding upper elastic arm portion5cand each through hole5fincludes a fringe portion5ethat faces the corresponding extension portion1f, and the adhesive GL inserted in the extension portion1fspreads to a portion of an upper surface of the upper first portion5aand a portion of a lower surface of the upper first portion5a, the portions extending along the fringe portion5e.

In this structure, each recess1bincludes an extension portion1fand each through hole5fincludes a fringe portion5ethat faces the corresponding extension portion1f. When the fringe portion5eis disposed so as to overlap part of the extension portion1ffilled with the adhesive GL, part of the adhesive GL squeezed by the upper first portion5alocated near the fringe portion5eeasily flows out to a portion of the upper surface of the upper first portion5aincluding the fringe portion5e. In addition, the provision of the fringe portion5efacing the extension portion1fcan increase the area over which the adhesive GL spreads to bond the upper leaf spring5to the lens holding member1. Specifically, the upper first portion5acan increase an area over which the adhesive GL spreads to bond the upper leaf spring5to the lens holding member1and the upper surface and the lower surface of the upper first portion5aare held with the adhesive GL. Thus, the end portions of the upper first portions5acan be securely joined to the fastening portions1dof the lens holding member1and the base portions of the upper elastic arm portion5care fixed.

This structure prevents the upper first portions5afrom rising in accordance with the operation of the upper elastic arm portions5c, whereby the biasing force can be prevented from varying due to the rise of the upper first portions5a. This structure thus enables production of a biasing force that varies to a lesser extent and is effective in providing a lens driving apparatus that operates more stably.

In the lens driving apparatus100according to the embodiment, in an initial state where an electrical current is not caused to pass through the coil4, the upper leaf spring5biases the lens holding member1upward whereas the lower leaf spring6biases the lens holding member1downward.

In this structure, in the initial state, the lens holding member1is held at a position at which a biasing force of the upper leaf spring5and a biasing force of the lower leaf spring6are in balance. Since the lens holding member1is held in this manner, the lens holding member1is movable in positive and negative optical axis directions from the position at which the lens holding member1is held in the initial state. Thus, when images are taken using an electronic device including the lens driving apparatus100, the device can focus on a subject by moving the lens holding member1by a minimum amount from the initial state.

In the lens driving apparatus100according to the embodiment, the adhesive GL with which the upper first portion5ais bonded to the mount surface1a(fastening portion1d, seeFIGS. 4A and 4B) of the lens holding member1is disposed at a portion that is open upward through the indentation7g.

This structure allows the adhesive GL, which is an ultraviolet curing adhesive, to cure by being easily irradiated with ultraviolet rays during assembly. This structure is also effective in allowing the amount of the applied adhesive GL to be easily checked and in, if the amount of the applied adhesive GL has been found insufficient after being checked, adding the adhesive GL.

As described above, the lens driving apparatus according to the embodiment of the present invention has been specifically described. The present invention, however, is not limited to the above-described embodiment and can be embodied in various manners without departing from the gist of the invention. For example, the present invention can be embodied in modifications described below, which also belong to the technical scope of the present invention.

Modified Example 1

In the lens driving apparatus100according to the first embodiment, the upper leaf spring5biases the lens holding member1upward and the lower leaf springs6bias the lens holding member1downward, so that, in the initial state, the lens holding member1is disposed at a position at which the biasing force of the upper leaf spring5and the biasing force of the lower leaf springs6are in balance. However, the upper leaf spring5and the lower leaf springs6may bias the lens holding member1downward so that, in the initial state, the lens holding member1is held in the state of being in contact with the base member8. Alternatively, the upper leaf spring5and the lower leaf springs6may bias the lens holding member1upward.

Modified Example 2

In the first embodiment, the moving mechanism50is constituted of the magnets3, the coil4, and the housing7serving as a yoke. However, the moving mechanism50may be constituted of the magnets3and the coil4.

Modified Example 3

In the first embodiment, the adhesive GL is an ultraviolet curing adhesive. The adhesive GL, however, may be other adhesives (for example, a thermoset adhesive or an ultraviolet cure/thermosetting adhesive) besides an ultraviolet curing adhesive.

Modified Example 4

In the first embodiment, an adhesive holding portion that faces the through hole5fof the upper leaf spring5is formed of the recess1bthat is recessed with respect to the mount surface1a. However, besides a recess, the adhesive holding portion may be a surface flush with the mount surface1a.