JP2012242648A - Lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive device capable of maintaining thrust and linearity of a lens holding member even when a winding width of a coil becomes narrow.SOLUTION: A lens drive device comprises: a lens holding member (5) for holding a lens body; a coil (59) mounted in the lens holding member (5) to form a gap between the coil (59) and an outer peripheral surface (68) around an optical axis of the lens holding member (5); a yoke (7) including an outer peripheral wall section (73) for surrounding the outside of the coil (59) and an inner wall section (74) opposed to the outer peripheral wall section (73) at the gap inside the coil (59); and a magnet (6) forming a magnetic circuit acting on the coil (59) together with the yoke (7). A flange section (53) opposed to an end of the inner wall section (74) in an optical axis direction is formed on the outer peripheral surface (68) of the lens holding member (5). The flange section (53) includes an escape portion (55) allowing the end of the inner wall section (74) to enter.

Description

  The present invention relates to a small lens driving device mounted on a camera-equipped mobile phone or the like.

  Conventionally, as a small lens driving device, one that magnetically drives a lens holding member holding a lens in an optical axis direction is known (for example, see Patent Document 1). The lens driving device described in Patent Document 1 is configured by placing a lens holding member equipped with a coil on a base member and covering the yoke from above. The lens holding member has a cylindrical portion that fixes the lens unit on the inside and a flange portion that protrudes outward from the lower portion of the cylindrical portion. A coil is attached to the range holding member with an interval on the outer peripheral surface of the cylindrical portion on the flange portion.

  The yoke has an outer peripheral wall portion that surrounds the outer side of the coil in the radial direction and an inner peripheral wall portion that surrounds the inner side of the coil in the radial direction. The outer peripheral wall portion and the inner peripheral wall portion are cross-sectional views U through the upper wall portion. It is connected in a letter shape. A magnet is fixed to the inner surface of the outer peripheral wall portion of the yoke so as to face the inner peripheral wall portion and the coil. In the lens driving device, a magnetic circuit is formed by the yoke and the magnet, and the lens holding member is moved in the optical axis direction by electromagnetic force generated by energization of the coil.

JP 2010-191130 A

  By the way, with the miniaturization of electronic equipment, further thinning of the lens driving device is desired, and it is assumed that the winding width of the coil will be narrowed in the future. For this reason, in order to give an appropriate driving force to the lens holding member, it is necessary to generate an electromagnetic force on the coil in a parallel magnetic field. However, in the lens driving device described above, in consideration of interference between the inner wall portion of the yoke and the flange portion of the lens holding member, the length of the inner wall portion cannot be sufficiently set in accordance with the winding width of the coil. As a result, the magnetic field cannot be uniformly applied to the coil by the inner wall portion and the magnet, and the thrust and linearity of the lens holding member are problematic.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a lens driving device capable of maintaining the thrust and linearity of the lens holding member.

  The lens driving device according to the present invention includes a coil attached to the lens holding member so as to form a gap between the lens holding member holding the lens body and the outer peripheral surface around the optical axis of the lens holding member. And a yoke having an outer wall portion that surrounds the outside of the coil and an inner wall portion that faces the outer wall portion in the gap inside the coil, and a magnetic member that forms a magnetic circuit that acts on the coil together with the yoke. A flange portion is formed on the outer peripheral surface of the lens holding member below the coil in the optical axis direction, and the flange portion is provided with a relief portion into which an end portion of the inner wall portion can enter. It is characterized by.

  According to this configuration, the escape portion formed in the flange portion of the lens holding member avoids interference between the inner wall portion of the yoke and the flange portion when the lens driving device is driven. Thereby, the inner wall part of a yoke can be taken long and a magnetic field can be made to act uniformly with respect to a coil along an optical axis direction at the time of the drive of a lens drive device. Therefore, the thrust and linearity of the lens holding member can be maintained even when the coil winding width is narrow.

  According to the present invention, in the lens driving device, the escape portion is formed so as to penetrate the flange portion in the optical axis direction. According to this configuration, the inner wall portion of the yoke can be inserted into the escape portion when the lens driving device is driven, and the inner wall portion can be formed longer.

  According to the present invention, in the lens driving device, the escape portion is formed so that a claw portion of a jig that supports winding of the coil around the lens holding member can be inserted. According to this configuration, when the coil is wound around the lens holding member, the escape portion can function as an insertion hole through which the claw portion of the jig is inserted. Accordingly, the coil can be wound around the lens holding member in a state where the coil is supported by the claw portion inserted through the escape portion, and the coil can be prevented from sagging.

  According to the present invention, the lens driving device further includes a lower case that supports the lens holding member on a substrate on which an imaging element is mounted, and a support surface that supports the lens holding member of the lower case is attached to the lens body. An opening that exposes the image sensor and an annular convex that surrounds the opening are formed inside the flange. According to this configuration, even when a foreign object passes through the gap between the coil and the outer peripheral surface of the lens holding member and further enters the lens driving device via the relief portion of the flange portion, Intrusion of foreign matter to the opening side is prevented by the provided annular convex portion. Therefore, foreign matter does not enter the element surface of the image sensor located in the opening.

  According to the present invention, the thrust and linearity of the lens holding member can be maintained.

It is a whole perspective view of implementation of the lens drive device concerning the present invention. It is a disassembled perspective view of the lens drive device concerning this embodiment. It is a cross-sectional view explaining the relationship between the inner wall part and escape part of the lens drive device which concerns on this Embodiment. It is a longitudinal cross-sectional view explaining the relationship between the inner wall part and escape part of the lens drive device which concerns on this Embodiment. It is a figure which shows the relationship between the movement amount of the lens drive device which concerns on this Embodiment, and an electric current. It is explanatory drawing of the first half of the assembly operation | work of the lens drive device which concerns on this Embodiment. It is explanatory drawing of the second half of the assembly operation | work of the lens drive device which concerns on this Embodiment. It is a figure which shows the winding state of the coil of the lens drive device which concerns on this Embodiment. It is operation | movement explanatory drawing of the lens drive device which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the following lens drive devices are examples, and are not limited thereto.

  FIG. 1 is an overall perspective view of the lens driving device according to the present embodiment. FIG. 2 is an exploded perspective view of the lens driving device according to the present embodiment.

  As shown in FIGS. 1 and 2, the lens driving device 1 is mounted on a substrate on which an image sensor (not shown) as an image sensor is mounted, and a lens body (not shown) is lighted with respect to the image sensor. It is driven in the axial direction to adjust the focal length. In the lens driving device 1, a lens holding member 5 is attached via a lower leaf spring 4 on a lower case 2 to which an external terminal 3 is attached. A coil 59 is wound around the lens holding member 5, and a yoke 7 with a magnet 6 is fixed to the lower case 2 so as to cover the coil 59. A top cover 9 is attached to the upper surface of the yoke 7 via an upper leaf spring 8.

  The lower case 2 is formed in a thin box shape having a lower surface opened by a synthetic resin. A rectangular opening 21 is formed at the center of the upper wall portion of the lower case 2, and the image sensor on the substrate is exposed upward through the opening 21. Around the rectangular opening portion 21, an annular convex portion 22 that prevents foreign matter from entering the center side of the lower case 2 is formed. At the four corners of the upper wall portion of the lower case 2, positioning convex portions 23 for positioning the lower leaf spring 4 and projections 24 for fixing the lower leaf spring 4 are formed. The lower leaf spring 4 is attached to the lower case 2 in a state where it is positioned in the front-rear and left-right directions by the positioning convex portion 23 and the protruding portion 24.

  The lower case 2 is insert-molded with a conductive metal plate 25. The metal plate 25 is partially exposed from the lower case 2, and the yoke 7 is electrically connected. A pair of attachment holes 26 and protrusions 27 for attaching the pair of external terminals 3 are formed around two adjacent corners of the lower case 2. The pair of external terminals 3 is formed by bending a part of a conductive metal plate. The external terminal 3 is fixed to the lower case 2 by thermal caulking of the protruding portion 27 in a state where the bent side plate portion is inserted into the mounting hole 26 and the protruding portion 27 protrudes from the insertion hole 31 formed in the flat plate portion. The

  The lower leaf spring 4 is made of conductive phosphor bronze or the like, and includes a pair of spring pieces 41. The pair of spring pieces 41 are arranged so as to form an opening at the center along the annular convex portion 22 of the lower case 2. Each spring piece 41 includes an outer plate portion 42 positioned on the radially outer side, an inner plate portion 43 positioned on the radially inner side, and a meandering spring plate portion 44 connecting the outer plate portion 42 and the inner plate portion 43. have. An insertion hole 46 is formed in the outer plate 42 corresponding to the protrusion 24 of the lower case 2, and an insertion hole is formed in the inner plate 43 corresponding to the protrusion 56 (see FIG. 6D) of the lens holding member 5. 45 is formed.

  The outer plate portion 42 is fixed to the lower case 2 by causing the protrusion 24 of the lower case 2 to protrude from the insertion hole 46 and heat caulking the protrusion 24. The inner plate portion 43 is fixed to the lens holding member 5 by thermal caulking of the protruding portion 56 with the protruding portion 56 of the lens holding member 5 protruding from the insertion hole 45. Thus, the lower case 2 and the lens holding member 5 are connected via the lower leaf spring 4. Further, the spring plate portion 44 of each spring piece 41 applies an urging force to the lens holding member 5 toward the lower case 2 side. The pair of spring pieces 41 are electrically joined to the pair of external terminals 3 and are also joined to the end of the coil 59.

  The lens holding member 5 includes a cylindrical portion 52 that is formed of a synthetic resin and has an internal thread portion 51 formed on the inner peripheral surface thereof, and a flange portion 53 that protrudes radially outward from the lower end side of the cylindrical portion 52. ing. A lens unit (not shown) having an external thread portion formed on the outer peripheral surface is mounted inside the cylindrical portion 52. Four coil support portions 54 that support the coil 59 from the inside protrude from the outer peripheral surface of the cylindrical portion 52. An octagonal cylindrical coil 59 is formed by winding a conducting wire around a coil support portion 54 provided in the cylindrical portion 52. In this case, a gap is formed between the coil 59 and the cylindrical portion 52 so that an inner wall portion 74 of the yoke 7 described later is interposed.

  The flange portion 53 is formed with a relief portion 55 that is cut out corresponding to the inner wall portion 74 of the yoke 7. The escape portion 55 prevents interference between the lower end portion of the inner wall portion 74 of the yoke 7 and the flange portion 53 when the lens holding member 5 is moved upward. A plurality of protrusions 56 for fixing the lower plate spring 4 and a pair of tangling pins 57 around which both ends of the coil 59 are wound are formed on the lower portion of the lens holding member 5 (see FIG. 6D). . One end portion of the coil 59 is joined to one spring piece 41 while being wound around one binding pin 57, and the other end portion of the coil 59 is wound around the other binding pin 57 in the other state. It is joined to the spring piece 41. In addition, four leg portions 58 that are in contact with the lower case 2 are formed under the lens holding member 5.

  The yoke 7 has a box shape with an open bottom surface, and a window portion 72 that exposes the cylindrical portion 52 of the lens holding member 5 is formed on the upper wall portion 71. The yoke 7 is formed with four inner wall portions 74 that are opposed to the four corners of the outer peripheral wall portion 73 (outer wall portion) that is rectangular when viewed from above. Each inner wall 74 is inserted through a gap between the coil 59 and the cylindrical portion 52. Magnets 6 (magnetic members) are respectively attached to the four corners of the inner peripheral surface of the outer peripheral wall 73. The magnet 6 is formed in a trapezoidal shape in accordance with the corner of the yoke 7, and has a magnetic pole surface 67 parallel to the wall surface of the inner wall portion 74. Coils 59 are disposed between the magnet 6 and the inner wall 74 at the four corners of the yoke 7.

  Then, a magnetic circuit is formed by the yoke 7 and the magnet 6, and the lens holding member 5 is driven in the optical axis direction by energizing the coil 59. In addition, an edge 75 that is joined to the metal plate 25 of the lower case 2 is formed at the lower portion of the yoke 7. Insertion holes 76 for attaching the top cover 9 are formed at the four corners of the upper wall portion 71 of the yoke 7.

  The upper leaf spring 8 is formed of phosphor bronze or the like, and has an opening 81 having a smaller diameter than the window 72 of the yoke 7. The upper leaf spring 8 has an outer plate portion 82 located on the radially outer side, an inner plate portion 83 located on the radially inner side, and a spring plate portion 84 connecting the outer plate portion 82 and the inner plate portion 83. ing. A cutout portion 85 is formed in the outer plate portion 82 corresponding to the insertion hole 76 of the yoke 7. The inner plate portion 83 is fixed to the upper end surface of the cylindrical portion 52 with an adhesive. The spring plate portion 84 of the upper plate spring 8 applies an urging force to the lens holding member 5 toward the lower case 2 side.

  The top cover 9 is formed in a rectangular frame shape from synthetic resin. At the four corners of the top cover 9, projections 91 for fixing the upper leaf spring 8 projecting from the lower surface are formed. The top cover 9 is integrated with the upper plate spring 8 and the yoke 7 by thermal caulking of the projection 91 in a state where the projection 91 is inserted into the notch 85 of the upper plate spring 8 and the insertion hole 76 of the yoke 7. The Details of the assembling work of the lens driving device 1 will be described later.

  Here, with reference to FIG.3 and FIG.4, the positional relationship of the inner wall part of a yoke and a lens holding member is demonstrated. FIG. 3 is a cross-sectional view illustrating the relationship between the inner wall portion and the relief portion of the lens driving device according to the present embodiment. FIG. 4 is a longitudinal sectional view for explaining the relationship between the inner wall portion and the relief portion of the lens driving device according to the present embodiment. 4A is a longitudinal sectional view of the lens driving device according to the present embodiment, and FIG. 4B is a longitudinal sectional view of the lens driving device according to the comparative example. Further, the lens driving device according to the comparative example is different from the lens driving device according to the present embodiment in that it does not mainly have an escape portion.

  As shown in FIGS. 3 and 4A, the yoke 7 has an outer peripheral wall portion 73 that is rectangular in a top view so as to surround the lens holding member 5, and magnets 6 are attached to the four corners of the outer peripheral wall portion 73, respectively. It has been. Further, the yoke 7 is formed with inner wall portions 74 so as to face the magnets 6 provided at the four corners of the outer peripheral wall portion 73 with a space therebetween. The inner wall portion 74 and the outer peripheral wall portion 73 are connected to each other in a U shape in a sectional view through the upper wall portion 71. The magnet 6, the upper wall portion 71, the outer peripheral wall portion 73, and the inner wall portion 74 form magnetic circuits at the four corners of the lens driving device 1.

  Further, the inner wall portion 74 of the yoke 7 is inserted into a gap between the outer peripheral surface 68 of the cylindrical portion 52 of the lens holding member 5 and the coil 59. With this configuration, the coil 59 is positioned between the magnetic pole surface 67 of the magnet 6 and the inner surface 77 of the inner wall portion 74, and the lens holding member 5 is moved in the optical axis direction by energization of the coil 59.

  Further, the flange portion 53 of the lens holding member 5 has a relief portion 55 corresponding to the inner wall portion 74. The escape portion 55 is formed at a position facing the lower end portion of the inner wall portion 74 in the optical axis direction, and is formed so that the inner wall portion 74 can be inserted. That is, the escape portion 55 exposed to the inside of the coil 59 is formed such that the dimension in the longitudinal direction is larger than the width dimension of the inner wall part 74 and the dimension in the short direction is larger than the thickness dimension of the inner wall part 74. ing.

  With such a configuration, even when the lens holding member 5 moves up, the lower end portion of the inner wall portion 74 does not come into contact with the flange portion 53 by the lower end portion of the inner wall portion 74 entering the escape portion 55. . In the present embodiment, by adopting a configuration in which interference between the inner wall portion 74 and the flange portion 53 can be avoided, the inner wall portion 74 is formed long in the optical axis direction, and the parallel between the inner wall portion 74 and the magnet 6 is achieved. The magnetic field range L is increased. For this reason, when the lens holding member 5 is driven, a magnetic field is uniformly applied to the coil 59 along the optical axis direction to generate a sufficient thrust on the lens holding member 5.

  On the other hand, as shown in FIG. 4B, the flange portion 102 of the lens driving device 101 according to the comparative example has no relief portion corresponding to the inner wall portion 103. In the lens driving device 101 according to the comparative example, the inner wall portion 103 is formed short in the optical axis direction in consideration of interference between the inner wall portion 103 and the flange portion 102 when the lens holding member 105 is driven. For this reason, the parallel magnetic field range L between the inner wall portion 103 and the magnet 106 is reduced, and a magnetic field cannot be uniformly applied to the coil 107 along the optical axis direction when the lens holding member 105 is driven. In particular, when the lens holding member 105 starts to be driven, the lower portion of the coil 107 protrudes from the gap between the magnet 106 and the inner wall portion 103, the magnetic field acting on the coil 107 is weak, and sufficient thrust is applied to the lens holding member 105. It cannot be generated.

  With reference to FIG. 5, the relationship between the movement amount of the lens driving device according to the present embodiment and the current will be described. FIG. 5 is a diagram illustrating the relationship between the amount of movement and current of the lens driving device according to the present embodiment. In FIG. 5, the characteristic of the lens driving device according to the present embodiment is indicated by a solid line, and the characteristic of the lens driving device according to the comparative example is indicated by a broken line.

  As shown by the solid line in FIG. 5, in the lens driving device 1 according to the present embodiment, when the coil 59 is energized, the initial number [mA] is determined by the urging force of the upper leaf spring 8 and the lower leaf spring 4. The movement of the holding member 5 is suppressed. Further, when the coil 59 is energized, the lens holding member 5 starts to move. Since the coil 59 continues to be positioned in the parallel magnetic field range L between the inner wall 74 and the magnet 6 from the start of movement of the lens holding member 5 to the stop of movement, a uniform magnetic field acts on the coil 59. Therefore, the linearity between the current for the coil 59 and the amount of movement of the lens holding member 5 is ensured.

  As shown by the broken line in FIG. 5, in the lens driving device 101 according to the comparative example, when the coil 107 is energized, the initial number [mA] is determined by the urging force of the upper leaf spring 108 and the lower leaf spring 104. The movement of 105 is suppressed. Further, when the coil 107 is energized, the lens holding member 105 starts to move. At the start of movement, a part of the coil 107 protrudes outside the parallel magnetic field range L between the inner wall portion 103 and the magnet 106. For this reason, a uniform magnetic field does not act on the coil 107, and the amount of movement of the lens holding member 105 gradually changes with respect to the current of the coil 107, as compared with the lens driving device 1 according to the present embodiment. . Therefore, in the lens driving device 101 according to the comparative example, the linearity between the current with respect to the coil 107 and the moving amount of the lens holding member 105 cannot be ensured.

  As described above, since the lens driving device 1 according to the present embodiment can uniformly apply a magnetic field to the coil 59, even when the winding width of the coil 59 is narrow, the thrust of the lens holding member and It is possible to maintain linearity. By the way, the flange portion 53 has a function of complicating a foreign substance entry path from the outside of the lens driving device 1 to the image sensor.

  However, in this embodiment, since the escape portion 55 is formed in the flange portion 53, the foreign matter enters the gap below the flange portion 53 through the clearance between the lens holding member 5 and the coil 59. There are cases (see FIG. 4A). Even in this case, the annular protrusion 22 protruding from the support surface 28 of the lower case 2 is prevented from entering the inside of the annular protrusion 22. Therefore, foreign matter does not enter the image sensor through the opening 21 formed in the support surface 28 of the lower case 2.

  Next, the assembly operation of the lens driving device will be described with reference to FIG. FIG. 6 is an explanatory diagram of the first half of the assembly operation of the lens driving device according to the present embodiment. FIG. 7 is an explanatory diagram of the latter half of the assembling work of the lens driving device according to the present embodiment. The following assembling work can be automatically performed by an automatic machine.

  As shown in FIG. 6A, the magnets 6 are fixed to the four corners of the yoke 7 by an adhesive. At this time, the magnetic pole surface of the magnet 6 is opposed to the wall surface of the inner wall portion 74 of the yoke 7 with a predetermined interval (see FIG. 4A). Next, as shown in FIG. 6B, the upper leaf spring 8 is placed on the upper surface of the yoke 7, and the top cover 9 is attached from above. At this time, the protrusions 91 at the four corners of the top cover 9 are respectively inserted into the notches 85 at the four corners of the upper leaf spring 8 and the insertion holes 76 at the four corners of the yoke 7. Then, the top cover 9, the upper plate spring 8, and the yoke 7 are integrated with each other by thermally crimping the protrusions 91 of the top cover 9.

  On the other hand, as shown in FIG. 6C, a coil 59 is wound around the outer periphery of the lens holding member 5. At this time, the lens holding member 5 is attached with a jig 95 for preventing a winding sag through a relief part 55 formed on the flange part 53, and the jig 95 prevents the coil 59 from sag. The That is, the escape portion 55 functions as an insertion hole through which the claw portion 96 of the jig 95 is inserted when the coil 59 is wound around the lens holding member 5. The coil 59 is wound around the lens holding member 5 in a state where the adjacent coil support portions 54 are supported by the claw portions 96.

  As shown in FIG. 8A, the coil 59 wound using the jig 95 does not sag even between adjacent coil support portions 54. On the other hand, when the escape portion is not formed in the flange portion 102 as in the lens driving device 101 according to the comparative example, the coil 107 using the jig 95 cannot be wound. Therefore, as shown in FIG. 8B, winding of the coil 107 occurs between adjacent coil support portions 111. Thus, in the present embodiment, the coil 59 can be satisfactorily wound around the lens holding member 5 by suppressing the looseness of the coil 59 by the claw portion 96 of the jig 95.

  Further, both end portions of the coil 59 wound around the lens holding member 5 are wound around the pair of binding pins 57. In this case, both ends of the coil 59 are wound after the insulating film is removed by a laser or the like. Next, as shown in FIG. 6D, a pair of spring pieces 41 is attached to the lower part of the lens holding member 5. At this time, the protrusions 56 of the lens holding member 5 are inserted into the insertion holes 45 of the pair of spring pieces 41, respectively. Then, the lens holding member 5 and the pair of spring pieces 41 are integrated by the caulking of the protrusion 56 of the lens holding member 5.

  Further, the end portion of the coil 59 wound around the binding pin 57 and the joint portion 62 of the pair of spring pieces 41 are laser soldered. At this time, the notch 63 in the vicinity of the joint 62 prevents heat escape at the joint 62, and the solder paste 65 is melted with a small amount of heating. Further, the notch 63 in the vicinity of the joint 62 suppresses the diffusion of the solder paste 65, and a good solder bridge is formed between the coil 59 and the joint 62. Thereby, a pair of spring piece 41 and the both ends of the coil 59 are electrically connected.

  Further, as shown in FIG. 7A, a pair of external terminals 3 are attached to the lower case 2. At this time, the external terminal 3 causes the side plate portion to be inserted into the mounting hole 26 of the lower case 2 and causes the protruding portion 27 of the lower case 2 to protrude from the insertion hole 31. And the lower case 2 and a pair of external terminal 3 are integrated by heat-caulking the protrusion part 27 of the lower case 2.

  As shown in FIG. 7B, the lens holding member 5 with the coil 59 is placed on the assembled lower case 2, and the lower case 2 and the lens holding member 5 are connected via the pair of spring pieces 41. It is attached. At this time, the protrusion 24 of the lower case 2 is inserted into the insertion holes 46 of the pair of spring pieces 41, and the protrusion 24 is thermally crimped, whereby the lower case 2 and the lens holding member 5 are integrated. The pair of spring pieces 41 are joined to the external terminals 3 by laser welding. Thereby, the pair of external terminals 3 and both ends of the coil 59 are electrically connected to both ends of the coil 59 via the pair of spring pieces 41.

  When the lower case 2 and the lens holding member 5 are integrated, as shown in FIG. 7C, the yoke 7 with the top cover 9 is covered from above. At this time, the inner wall portion 74 of the yoke 7 is inserted into the gap between the coil 59 of the lens holding member 5 and the cylindrical portion 52. As a result, at the four corners of the yoke 7, the coil 59 is interposed between the magnet 6 and the inner wall 74 to form a magnetic circuit. Further, the edge 75 of the yoke 7 is placed on the metal plate 25 of the lower case 2 and joined to the metal plate 25 by laser welding.

  Then, as shown in FIG. 7D, an adhesive is applied to the upper end surface of the cylindrical portion 52 and the inner plate portion 83 of the upper leaf spring 8 through the window portion 72 of the yoke 7. Thereby, the yoke 7 and the top cover 9 and the lens holding member 5 are connected via the upper leaf spring 8. The lens driving device 1 thus assembled is urged toward the lower case 2 by the leaf springs 4 and 8 provided on the upper and lower sides of the lens holding member 5. In the lens driving device 1, when the coil 59 around which the lens holding member 5 is wound is energized, the lens holding member 5 is moved in the optical axis direction against the urging force of the leaf springs 4 and 8.

  Hereinafter, the operation of the lens driving device will be described with reference to FIG. FIG. 9 is an explanatory diagram of the operation of the lens driving device according to the present embodiment.

  As shown in FIG. 9, the magnet 6 is fixed to the four corners of the outer peripheral wall portion 73 of the yoke 7, and the inner wall portion 74 is positioned so as to face the magnetic pole surface 67 of the magnet 6. A circuit is formed. A coil 59 wound around the lens holding member 5 is interposed between the magnet 6 and the inner wall portion 74. The magnetic circuit is formed so that the magnetic flux lines generated on the magnetic pole surface 67 of the magnet 6 pass through the coil 59 toward the inner wall 74. The lens holding member 5 is pretensioned on the lower case 2 side by an upper leaf spring 8 and a lower leaf spring 4.

  When the coil 59 is energized in this initial state, an electromagnetic force is generated in the optical axis direction with respect to the coil 59. Due to the electromagnetic force generated in the coil 59, the lens holding member 5 moves in the optical axis direction against the urging force of the upper plate spring 8 and the lower plate spring 4, and a focal point between a lens body (not shown) and the image sensor. The distance is adjusted. In this case, since the inner wall portion 74 of the yoke 7 and the magnetic pole surface of the magnet 6 are parallel, the amount of magnetic flux lines passing through the coil 59 is large, and magnetic circuits are formed only at the four corners of the lens driving device 1. It is possible to generate a sufficient driving force.

  In addition, the coil 59 moves in the parallel magnetic field range L between the inner wall 74 and the magnet 6 from the start to the stop of the movement of the lens holding member 5. Therefore, since the magnetic field acts uniformly on the coil 59 during the movement of the lens holding member 5, the thrust and linearity of the lens holding member 5 can be ensured. When the energization of the coil 59 is stopped, the lens holding member 5 is pulled back to the initial position by the restoring force of the upper leaf spring 8 and the lower leaf spring 4.

  As described above, according to the lens driving device 1 according to the present embodiment, the relief portion 55 formed in the flange portion 53 of the lens holding member 5 causes the inner wall portion 74 of the yoke 7 to be connected to the lens 7 when the lens holding member 5 is driven. Interference with the flange portion 53 is avoided. For this reason, the inner wall 74 of the yoke 7 can be made long, and a magnetic field can be applied uniformly to the coil 59 along the optical axis direction when the lens holding member 5 is driven. Therefore, the thrust and linearity of the lens holding member 5 can be maintained even when the winding width of the coil 59 is narrow.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the present embodiment, the escape portion is formed by penetrating the flange portion, but the present invention is not limited to this configuration. The escape portion may be any configuration that allows the end portion of the inner wall portion to enter, that is, a configuration that can avoid interference between the inner wall portion and the flange portion, and may be, for example, a recess formed in the flange portion.

  In the present embodiment, the escape portion functions as an insertion hole through which the claw portion of the jig is inserted. However, the present invention is not limited to this configuration. The escape portion may have only a function of avoiding interference between the inner wall portion and the flange portion.

  In the present embodiment, the magnet is exemplified as the magnetic member, but the present invention is not limited to this configuration. The magnetic member may be anything as long as it forms a magnetic circuit with the yoke. Moreover, in this Embodiment, although it was set as the structure which attaches a magnet to the outer peripheral wall part of a yoke, it is not limited to this structure. The magnet only needs to form a parallel magnetic field with the inner wall portion of the yoke, and may be configured to be supported by the lower case, for example.

  In this embodiment, the lens driving device is assembled by an automatic machine. However, the present invention is not limited to this configuration. The lens driving device may be assembled manually, or the lens driving device may be assembled by combining an automatic machine and manual.

  Moreover, in this Embodiment, it is not limited to the above-mentioned assembly order. For example, after the end of the coil is wound around the binding pin, the insulating coating on the end of the coil may be peeled off. Further, the end of the coil may be joined to the biasing member before the biasing member is fixed to the lens holding member.

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Lower case 3 External terminal 4 Lower leaf | plate spring 5 Lens holding member 6 Magnet (magnetic member)
7 Yoke 8 Upper leaf spring 9 Top cover 21 Opening 22 Annular convex 28 Support surface 52 Cylindrical portion 53 Flange portion 54 Coil support portion 55 Escape portion 59 Coil 67 Magnetic pole surface 68 Outer surface 71 Upper wall portion 73 Outer wall portion ( Outer wall)
74 Inner wall part 95 Jig 96 Claw part

Claims (4)

A lens holding member for holding the lens body;
A coil attached to the lens holding member so as to form a gap with the outer peripheral surface around the optical axis of the lens holding member;
A yoke having an outer wall surrounding the outside of the coil and an inner wall facing the outer wall in the gap inside the coil;
A magnetic member that forms a magnetic circuit acting on the coil together with the yoke;
A flange portion is formed below the coil in the optical axis direction on the outer peripheral surface of the lens holding member, and the flange portion is provided with a relief portion into which an end portion of the inner wall portion can enter. A lens driving device.   The lens driving device according to claim 1, wherein the escape portion is formed to penetrate the flange portion in the optical axis direction.   The lens driving device according to claim 2, wherein the escape portion is formed so that a claw portion of a jig that supports winding of the coil around the lens holding member can be inserted. A lower case for supporting the lens holding member on a substrate on which an image sensor is mounted;
The support surface for supporting the lens holding member of the lower case is formed with an opening that exposes the imaging element to the lens body and an annular convex that surrounds the opening inside the flange. The lens driving device according to claim 1, wherein:

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