JP4813844B2 - Autofocus actuator - Google Patents

Description

  The present invention relates to an autofocus actuator, and more particularly to an autofocus actuator that can be used in a small electronic device with a camera such as a digital camera or a mobile phone.

  In a digital camera or the like, an actuator capable of moving a lens in the optical axis direction is used for the purpose of autofocus and zoom. This type of actuator moves the lens in the direction of the optical axis by the interaction between the magnetic field generated by the current flowing in the coil and the magnetic field generated by the permanent magnet. Recently, even in cameras mounted on mobile phones, the number of pixels of the image sensor has been changed to megapixels of 1 million pixels or more, so that an autofocus function has been required.

  As a conventional autofocus actuator, one disclosed in Japanese Patent Application Laid-Open No. 2003-295033 is known. This actuator generally supports a front lens, a front support frame that supports the front lens, a front coil attached to the front support frame, a front spring attached to the front support frame, a rear lens, and a rear lens. A rear support frame, a rear coil attached to the rear support frame, a rear spring attached to the rear support frame, a magnet, a magnet support, and a yoke. The front coil is disposed in the outer gap between the magnet and the yoke. The rear coil is disposed in the inner gap between the magnet and the yoke. By applying a current to the front coil, the front lens can be moved to a position that balances the elastic force of the front spring. Further, by applying a current to the rear coil, the rear lens can be moved to a position that balances the elastic force of the rear spring.

  The conventional actuator has a structure in which power is supplied to the coil via a front spring and a rear spring. Accordingly, it is necessary to provide coil and power supply electrode portions on the front spring and the rear spring, respectively. In order to form such an electrode portion, it is necessary to bend the front spring and the rear spring. Therefore, there arises a problem that the yield and productivity of the spring are lowered.

  In addition, since the coil and the conductive wire are directly soldered to the spring itself to establish conduction, it is necessary to insulate the spring from other components. This causes a problem that the number of parts of the actuator increases.

  Furthermore, since the front spring and the rear spring have different shapes, there arises a problem that the manufacturing cost of the spring increases.

  In order to solve the above problems, the present inventors have devised the autofocus actuator shown in FIGS.

JP 2003-295033 A

  The problems in the conventional actuator can be solved by the actuator shown in FIGS. However, both the above conventional actuator and the actuator shown in FIGS. 1 to 14 use a yoke having a cylindrical shape. In such a cylindrical yoke, the permanent magnet to be housed or assembled also needs to have a curved shape in an arc shape. However, since such a curved permanent magnet is expensive, there is a problem that the cost of parts increases. is there.

  In addition, a jig for positioning a permanent magnet that is curved with respect to the yoke must be used during assembly, resulting in a complicated assembly process.

  Furthermore, a magnet support or the like that can position the permanent magnets in advance must be assembled to the yoke, which increases the number of parts.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a rectangular parallelepiped, that is, a flat permanent magnet, and an autofocus having a yoke that can be easily positioned and assembled. It is to provide an actuator.

In order to achieve the above object, an autofocus actuator according to the present invention includes a holder having a cylindrical portion having a lens attached to one end thereof, and a coil provided so as to be positioned around the cylindrical portion of the holder. A pair of leaf springs provided on both sides of the cylindrical portion of the holder in the optical axis direction and supporting the holder so as to be displaceable in the optical axis direction with the holder positioned in a radial direction, and a plurality of the plate springs facing the coil In order to adjust the position of the lens attached to the holder in the direction of the optical axis by the interaction between the magnetic field generated in the coil by energizing the coil and the magnetic field of the permanent magnet. The yoke, the inner cylinder portion through which the cylindrical portion of the holder is inserted, the yoke being positioned at a predetermined interval on the outer side of the inner cylinder portion, and having four corner portions and four inner surfaces. Yes That has a cross section outer tube portion formed in a tubular shape of a square, the ends of the lens side of the holder in the inner cylinder portion and the outer cylindrical portion and a connecting portion integrally connected to the outer cylinder portion Each of the four inner surfaces forms a planar magnet mounting surface, and the permanent magnet is composed of four substantially flat plate permanent magnets, and is disposed on each of the magnet mounting surfaces, of the outer tube portion of the yoke. All of the four corners are recessed inward, and positioning surfaces are formed on both sides of the magnet mounting surface in accordance with the size of the substantially flat permanent magnet. .

Further, autofocus actuator of the present invention, the inner cylindrical portion of the yoke is formed in a substantially square section, said coil in a substantially square shape so as to be arranged at predetermined intervals around the inner cylinder portion A wound cylindrical coil is preferable.

Furthermore, the autofocus actuator of the present invention preferably further includes magnetic flux leakage prevention means for preventing leakage of magnets from the four permanent magnets provided in the yoke. In the autofocus actuator of the present invention, the magnetic flux leakage preventing means is disposed so as to connect the permanent magnets in contact with the surfaces of the four permanent magnets provided on the yoke. A member is preferred. In the autofocus actuator of the present invention, the surface of the magnetic member opposite to the surface in contact with the four permanent magnets is positioned closer to the connecting portion side of the yoke than the end surface of the outer cylindrical portion of the yoke. It is preferable to have such a thickness.
According to another aspect of the autofocus actuator of the present invention, there is provided a holder having a cylindrical portion having a lens attached to one end thereof and a flange portion provided on the outer periphery of the other end of the cylindrical portion; A coil provided in the flange portion so as to be positioned around the cylindrical portion, an inner cylindrical portion forming an insertion hole through which the cylindrical portion of the holder is inserted, and a predetermined interval outside the inner cylindrical portion The outer cylinder part formed in the shape of a cylinder with a substantially square cross section having four corners and four inner surfaces, and the end part on the lens side of the holder of the inner cylinder part and the outer cylinder part A planar magnet mounting formed by a yoke having a connecting portion integrally connected and configured to accommodate the coil in the space of the predetermined interval, and each of four inner surfaces of the outer cylindrical portion of the yoke Facing the coil with a gap Are provided on both sides in the optical axis direction of the cylindrical portion of the holder, and are supported so as to be displaceable in the optical axis direction with the holder positioned in the radial direction. A pair of leaf springs and outer sides of the pair of leaf springs, sandwiching the pair of leaf springs between both end surfaces in the optical axis direction of the yoke, and at least attached to the holder And a pair of support frames each having an opening in a portion corresponding to the lens, and by energizing the coil, the position of the lens attached to the holder can be adjusted in the optical axis direction. The four corners of the outer cylindrical portion of the yoke are all recessed toward the inside, and the substantially flat plate-like shape is formed on both sides of the magnet mounting surface. Hisashi forms a positioning surface to match the size of the magnet, characterized in that a magnetic flux leakage prevention means for preventing the leakage of magnetic flux from the open portion opposite to the connecting portion of the yoke.

  According to the autofocus actuator of the first aspect, the substantially flat plate-like permanent magnet can be used, so that the component cost can be reduced.

  According to the autofocus actuators of the second and third aspects, a sufficient magnetic field can be formed in a predetermined space of the yoke using a substantially flat permanent magnet. Moreover, since the inner surface of the outer cylinder part of the yoke formed in the cylinder shape with a substantially square cross section is used as the magnet mounting surface, the assembly of the magnet can be facilitated.

  According to the autofocus actuator of the fourth aspect, when the permanent magnet is disposed on the yoke, the substantially flat permanent magnet can be easily formed without using a positioning jig or providing a magnet support. Can be positioned.

  According to the autofocus actuator of the fifth aspect, since the direction of the magnetic field and the direction of the current flowing in the coil are substantially perpendicular, the driving force in the optical axis direction of the holder is improved.

  According to the autofocus actuator of claim 6, the substantially flat plate-like permanent magnet can be easily positioned, and the cross-sectional shape of the substantially flat plate-like permanent magnet is almost circular, so that the cross-sectional shape is substantially circular. Even if the coil is used, the holder can obtain a sufficient driving force in the optical axis direction.

  The above-described and other configurations, operations, and effects of the present invention will become more apparent from the following description of the basic configuration and preferred embodiments with reference to the drawings.

  Hereinafter, an autofocus actuator proposed by the present inventors, which is a premise of the present invention, will be described based on the attached drawings.

  FIG. 1 is a perspective view of the appearance of an autofocus actuator. FIG. 2 is an exploded perspective view of the autofocus actuator shown in FIG. FIG. 3 is a schematic cross-sectional view of the autofocus actuator shown in FIG.

  This autofocus actuator (hereinafter also simply referred to as “actuator”) 1 includes a cylindrical portion 11 having a lens assembly 100 attached to one end thereof and a cylinder thereof, as schematically shown in FIGS. A holder 10 having a flange portion 12 provided on the outer periphery of the other end of the cylindrical portion 11; a coil 20 fixed to the flange portion 12 at a distance from the periphery of the cylindrical portion 11 of the holder 10; An inner cylinder part 31 having an insertion hole 35 through which the cylindrical part 11 is inserted, an outer cylinder part 32 provided at a predetermined interval outside the inner cylinder part 31, and the inner cylinder part 31 and the outer cylinder part 32. The holder 10 has a connecting portion 34 (see FIGS. 4 and 5) in which the end opposite to the flange portion 12 is integrally connected, and a predetermined interval between the inner cylindrical portion 31 and the outer cylindrical portion 32 is provided. Configured to accommodate coil 20 in space A plurality of cylindrical yokes 30 arranged to face the coil 20 at intervals with a magnet mounting surface 33 (see FIG. 4) on the inner peripheral surface of the outer cylindrical portion 32 of the cylindrical yoke 30. A permanent magnet 40; a magnetic member 50 arranged to connect a plurality of permanent magnets 40 in contact with the surface of the permanent magnet 40 opposite to the connecting portion 34 of the cylindrical yoke 30; A pair of leaf springs 60 comprising an upper leaf spring 60U and a lower leaf spring 60L, which are provided on both sides of the cylindrical portion 11 in the optical axis direction and support the holder 10 so as to be displaceable in the optical axis direction with the holder 10 positioned in the radial direction. A stopper 70 attached to the holder 10 so as to sandwich the upper leaf spring 60U with the holder 10; provided on the outer side in the optical axis direction of each of the pair of leaf springs 60; Both end faces of the optical axis A cover 80 and a base 85 forming a pair of support frames each having an opening 80a, 85a at least in a portion corresponding to the lens assembly 100 attached to the holder 10, and a lower leaf spring 60L and a base And a sheet-like electrode 90 provided for supplying power to the coil 20.

  In the actuator as described above, the lens assembly 100 includes a plurality of lenses (not shown). In other words, the plurality of lenses are attached to one end of the cylindrical portion 11. However, the position where the plurality of lenses (lens assembly 100) are attached to the cylindrical portion 11 is not limited thereto.

  Hereinafter, details of each component will be described. In the present specification, the terms “upper” and “lower” are used as appropriate. In the description of each member, the direction of the arrow shown in FIG. 2 is the upward direction, and the opposite direction of the arrow is the downward direction.

  The holder 10 is a molded product made of synthetic resin. A cylindrical tubular portion 11 to which the lens assembly 100 is attached from one end side (upper end side) and a circular flange portion 12 provided integrally on the outer periphery of the other end side (lower end side) of the tubular portion 11. Have. As shown in FIG. 3, the cylindrical portion 11 of the holder 10 is hollow. On the inner peripheral surface of the cylindrical portion 11, a female screw portion for screwing with a male screw portion formed on the outer periphery of the lens assembly 100 is formed. Further, a step portion 12a for bonding the coil 20 in a state where the coil 20 is positioned with respect to the holder 10 is provided on the peripheral portion of the upper surface of the flange portion 12 (surface on the cylindrical portion 11 side) (see FIG. 3). ). Further, a ring-shaped convex portion (step portion) 15 for positioning the lower leaf spring 60 </ b> L with respect to the holder 10 is formed substantially concentrically on the lower surface of the flange portion 12. On the convex portion 15, three thin protrusions 13 extending in a direction parallel to the optical axis are formed integrally with the convex portion 15 at equal intervals.

  As described above, the coil 20 is fixed to the step portion 12 a on the upper surface of the flange portion 12 of the holder 10 so as to be spaced from the periphery of the cylindrical portion 11 of the holder 10. The coil 20 uses a copper wire whose surface is coated. Further, the coil 20 is formed by different numbers of turns in which a 10-turn layer and a 9-turn layer of copper wire are alternately stacked. The cross section of the coil 20 is a circular air-core coil. Further, the coil 20 is wound so that the leading portions 21 at both ends of the winding are positioned on the flange portion 12 side. Such an air core coil is fixed to the step portion 12a on the upper surface of the flange portion 12 of the holder 10 with an adhesive. In addition, the coil 20 is not limited to the above air core coil, For example, the coil may be wound around the cylindrical part 11 directly.

  As shown in FIG. 4, the yoke 30 is provided with a cylindrical inner cylinder part 31 having an insertion hole 35 through which the cylindrical part 11 of the holder 10 is inserted, and outside the inner cylinder part 31 at a predetermined interval. It has the cylindrical outer cylinder part 32 and the connection part 34 which the edge part on the opposite side to the flange part 12 of the holder 10 of the inner cylinder part 31 and the outer cylinder part 32 connects integrally. The coil 20 is accommodated in a space at a predetermined interval between the inner cylinder portion 31 and the outer cylinder portion 32 of the yoke 30.

  The yoke 30 is made of, for example, a nickel-plated iron surface that is a magnetic material. The cylindrical portion 11 of the holder 10 is inserted into the insertion hole 35 of the inner cylindrical portion 31 so as to be movable in the optical axis direction. Therefore, the diameter of the insertion hole 35 of the inner cylinder part 31 is formed so as to be larger than the diameter of the outer peripheral surface of the cylindrical part 11 of the holder 10 and smaller than the diameter of the peripheral part of the flange part 12 of the holder 10. .

  Further, as shown in FIGS. 2 to 4, the height in the optical axis direction of the inner cylinder portion 31 with respect to the connecting portion 34 is formed to be lower than the height in the optical axis direction of the outer cylinder portion 32. .

  A plurality (four pieces) of permanent magnets 40 are arranged on the magnet mounting surface 33 on the inner peripheral surface of the outer cylindrical portion 32 of the cylindrical yoke 30 so as to face the coil 20 with a space therebetween. The magnet mounting surface 33 is not limited to being provided on the inner peripheral surface of the outer cylindrical portion 32 of the yoke 30 as described above, and may be provided on the outer peripheral surface of the inner cylindrical portion 31.

  Each of these permanent magnets 40 is formed of a permanent magnet that is curved in an arc shape of approximately 90 degrees so as to follow the shape of the circular magnet mounting surface 33. The permanent magnet 40 is a neodymium magnet. For example, the curved surface on the side abutting on the magnet mounting surface 33 is magnetized so as to be the S pole, and the curved surface substantially opposite to the curved surface is the N pole. By attaching these arc-shaped permanent magnets 40 to the cylindrical yoke 30, the outer peripheral surface of the inner cylindrical portion 31 of the yoke 30 becomes an S pole. Thereby, the magnetic field which goes to the inner cylinder part 31 from the permanent magnet 40 curved in circular arc shape is formed. When the coil 20 is energized, a force in the optical axis direction acts on the coil 20 due to the interaction between the magnetic field generated by the current flowing through the coil 20 and the magnetic field formed by the permanent magnet 40. Thereby, the holder 10 (that is, the lens assembly 100) can be moved in the optical axis direction. The number of permanent magnets is not limited to four pieces, and a plurality of other permanent magnets may be used. The permanent magnet may be a single C-shaped permanent magnet, for example.

  By the way, in the yoke 30 as described above, as shown by the arrow in FIG. 5, the magnetic flux leaks downward between the adjacent permanent magnets 40 at the open portion opposite to the connecting portion 34 of the cylindrical yoke 30. End up. In order to prevent such leakage of magnetic flux, it is desirable to provide magnetic flux leakage prevention means on the yoke 30 to increase the driving force of the holder 10.

  As a means for preventing the leakage of magnetic flux, the magnet connected to the permanent magnet 40 while being in contact with the lower end surface of the permanent magnet 40, that is, the surface opposite to the surface in contact with the connecting portion 34 of the cylindrical yoke 30. A member 50 is arranged.

  By providing the magnetic member 50, the magnetic flux leaking downward is reduced as shown in FIG. Thereby, the magnetic flux which goes to the inner cylinder part 31 of the cylindrical yoke 30 from the permanent magnet 40 increases. In this actuator 1, a circular ring-shaped magnetic member 50 as shown in FIG. 7 is attracted to the permanent magnet 40, and the magnetic member 50 and the permanent magnet 40 are fixed with an adhesive. As shown in FIG. 6, the width of the ring-shaped magnetic member 50 is equal to the radial thickness of the permanent magnet 40 curved in an arc shape. Thereby, arrangement | positioning of the coil 20 accommodated in the yoke 30 is not prevented. Further, the bottom surface of the ring-shaped magnetic member 50 is positioned above the end surface of the outer cylindrical portion 32 of the yoke 30 in a state where the magnetic member 50 is attached to the permanent magnet 40. Thereby, attachment of the lower leaf | plate spring 60L adhere | attached on the end surface of the outer cylinder part 32 of the yoke 30 is not prevented. In addition, the bottom surface of the magnetic member 50 may be configured to have the same size as the end surface of the outer cylindrical portion 32 of the yoke 30 in the optical axis direction, and the magnetic member 50 may be attached to the lower end surface of the permanent magnet 40. In this case, the bottom surface of the magnetic member 50 can be used as an adhesive surface with the lower leaf spring 60L.

  Further, the shape of the corner formed by the magnet mounting surface 33 and the connecting portion 34 of the yoke 30 may be different from the shape of the corresponding corner of the permanent magnet 40. Therefore, the corresponding surface of the permanent magnet 40 may not come into surface contact with the magnet mounting surface 33 of the yoke 30, resulting in a decrease in magnetic efficiency. In such a case, by inserting another magnetic member 50 between the connecting portion 34 of the yoke 30 and the upper surface of the permanent magnet 40, the shape of the corner portion formed by the magnet mounting surface 33 of the yoke 30 and the connecting portion 34 is obtained. The permanent magnet 40 can be brought into surface contact with the magnet mounting surface 33 of the yoke 30 without being affected.

  In the actuator 1, the cold rolled steel plate is used for the magnetic member 50. However, the magnetic member 50 is not limited to this, and may be formed of a magnetic material made of iron, nickel, cobalt, and alloys thereof.

  Similarly, when using one C-shaped permanent magnet, for example, the magnetic member 50 is disposed in contact with the lower end surface of the permanent magnet 40. Thereby, the magnetic flux which leaks below can be reduced between the end surfaces of the circumferential direction which a C-shaped permanent magnet faces.

  As shown in FIG. 8, the leaf spring 60 (upper leaf spring 60U, lower leaf spring 60L) is made of a thin metal plate. The upper leaf spring 60U and the lower leaf spring 60L connect the inner ring portion 61, the outer ring portion 62 provided at a predetermined interval from the inner ring portion 61, and the inner ring portion 61 and the outer ring portion 62, respectively. And a plurality of connecting portions 63. When a load is applied to the inner ring portion 61 with the outer ring portion 62 fixed, the connecting portion 63 is elastically deformed. Thereby, in a state where the holder 10 to which the inner ring portion 61 is bonded is positioned in the radial direction (that is, in a state where the displacement of the holder 10 in the radial direction is limited), the upper leaf spring 60U and the lower leaf spring 60L are 10 is supported so as to be displaceable in the optical axis direction.

  On the upper surface of the holder 10, a step portion 16 is formed for positioning the upper leaf spring 60U with respect to the holder 10 during assembly. The cross-sectional shape of the step portion 16 has a shape corresponding to the inner peripheral edge of the inner ring portion 61 (see FIG. 2). The inner ring portion 61 of the upper leaf spring 60U is placed on the upper surface of the holder 10 in a state of fitting with the step portion 16, and the stopper 70 is further mounted thereon. As a result, the inner ring portion 61 is bonded to the holder 10 while being sandwiched between the upper surface of the holder 10 and the lower surface of the stopper 70. Further, the outer ring portion 62 is bonded to the cover 80 and the yoke 30 while being sandwiched between the lower surface of the cover 80 and the upper surface of the connecting portion 34 of the yoke 30.

  As described above, the step portion 15 for positioning the lower leaf spring 60L is also formed on the lower surface of the flange portion 12 during assembly. The cross-sectional shape of the step portion 15 has a shape corresponding to the inner peripheral edge of the inner ring portion 61. The inner ring portion 61 is bonded in a state of being positioned with respect to the holder 10. The outer ring portion 62 is bonded to the base 85 and the yoke 30 while being sandwiched between the end surface of the outer cylinder portion 32 of the cylindrical yoke 30 and the upper surface of the base 85.

  As shown in FIG. 3, the sheet electrode 90 is provided between the lower leaf spring 60 </ b> L and the base 85 in order to supply power to the coil 20. As shown in FIG. 9, the sheet-like electrode 90 is made of a polyimide sheet material. The sheet-like electrode 90 includes a ring-shaped portion 91 formed in a substantially circular ring shape, and an extending portion 92 that extends radially outward from the ring-shaped portion 91.

  Two terminal portions 93 made of copper are provided on one surface of the sheet-like electrode 90 from the extending portion 92 to the ring-shaped portion 91. In the ring-shaped portion 91, a dummy terminal portion 95 for soldering a dummy wire 23 described later is provided between the tips of the two terminal portions 93.

  Furthermore, an adhesive layer (not shown) for bonding the sheet electrode 90 to the lower surface of the outer ring portion 62 of the lower leaf spring 60L is provided on the other surface of the sheet electrode 90, and the ring portion 91 extends. The portion 92 is provided in the vicinity of the connection portion with the ring-shaped portion 91 and in the vicinity of the distal end portion of the extension portion 92.

  Further, the extending portion 92 extends to the outside of the support frame through an insertion hole 88 of the base 85 described later and is connected to a sensor substrate (not shown). In order to insert the extension 92 into the insertion hole 88, it is necessary to bend the extension 92 approximately 90 degrees with respect to the ring-shaped portion 91. In order to prevent the terminal portion 93 from being damaged by this bending, a cover film 94 made of polyimide is provided on the terminal portion 93.

  Electric power can be supplied to the coil 20 by soldering the tips of the two lead portions 21 of the coil 20 to the two terminal portions 93 provided on the ring-shaped portion 91 of the sheet-like electrode 90. However, undesired contact between the drawing portion 21 and other members caused by the displacement of the holder 10 and stress concentration occur near the soldered tip. Therefore, as shown in FIG. 10, the lead portions 21 on both sides of the winding of the coil 20 are wound around two of the three thin protrusions 13 provided on the step portion 15 on the lower surface of the flange portion 12 of the holder 10. Next, the leading end of the lead portion 21 is connected to the terminal portion 93 of the sheet electrode 90 via the soldering portion 22.

  Each of the protrusions 13 has a cylindrical shape having a height that does not contact an upper surface of a bottom plate portion 86 of the base 85 described later in an assembled state.

  The lead portion 21 extends from the coil 20 to the lower surface side of the flange portion 12 through a recess 14 (see FIG. 12) provided on the edge portion of the flange portion 12. Next, each of the drawer portions 21 is wound around the protrusion 13 near the recess.

  The lead-out portion 21 between the protrusion 13 and the soldering portion 22 is attached with a slack so that no tensile stress is generated in the lead-out portion 21 even when the holder 10 is displaced.

  Furthermore, in the actuator 1 described above, as shown in FIG. 11, the portion where the lead portion 21 is wound around the protrusion 13 of the holder 10 and the solder where the tip of the lead portion 21 is soldered to the terminal portion 93 of the sheet-like electrode 90. A stress relaxation agent 24 is provided so as to wrap around the attaching portion 22. Thereby, it is possible to prevent stress from concentrating on a part of the drawer portion 21.

  Furthermore, as shown in FIG. 12, three protrusions 13 are provided on the lower surface of the flange portion 12 at substantially equal intervals. The three protrusions 13 are inserted into the positions of substantially semicircular recesses 66 (see FIG. 8) at the inner edge of the inner ring portion 61 of the lower leaf spring 60L that is bonded to the lower surface of the flange portion 12, respectively.

  As described above, the lead portion 21 of the coil 20 is wound around two of the three protrusions 13. The remaining one is provided with balance holding means.

  This balance holding means includes a dummy wire 23 using the same wire as the winding of the coil 20. One end of the dummy wire 23 is wound around the protrusion 13, and the other end is soldered to the dummy terminal portion 95 of the sheet-like electrode 90. Thereby, the balance of the weight of the holder 10 can be maintained, and the holder 10 can be displaced in the optical axis direction in a stable posture.

  The dummy wire 23 is also provided with a stress relaxation agent 24 so as to wrap the portion wound around the protrusion 13 and the soldered portion of the dummy wire 23. Thereby, stress can be prevented from concentrating on a part of the dummy wire 23 and the balance of the weight of the holder 10 can be maintained.

  The actuator 1 is not limited to using the sheet electrode 90 as described above. For example, a terminal portion that is connected to the power source portion via an insulating material is formed on a part of the lower surface (surface opposite to the holder 10) of the outer ring portion 62 of the lower leaf spring 60L that does not displace with the displacement of the holder 10. It may be formed and the tip of the lead portion 21 of the coil 20 may be connected to the terminal portion.

  As shown in FIG. 13, the stopper 70 is made of a synthetic resin formed in a ring shape, and is bonded in a state where the inner ring portion 61 of the upper leaf spring 60 </ b> U is sandwiched between the holder 10.

  A part of the edge of the three openings 71 is positioned so as to coincide with the shape of the substantially semicircular recess 65 (see FIG. 8) at the outer edge of the inner ring part 61 of the upper leaf spring 60U. Assembled. Therefore, the clearance between the cylindrical portion 11 of the holder 10 and the inner cylindrical portion 31 of the yoke 30 can be confirmed through the opening 71 and the substantially semicircular concave portion 65 from the upper surface side.

  As shown in FIG. 2, a part of the outer ring portion 62 of the upper leaf spring 60 </ b> U is assembled while being sandwiched between the connecting portion 34 of the yoke 30 and the cover 80. The cover 80 includes a substantially rectangular upper plate portion 81 having an opening 80a, and a plurality of column portions 82 provided at the corners of the upper plate portion 81 at right angles to the upper plate portion 81 and downward. Have

  A part of the outer ring portion 62 of the lower leaf spring 60L is assembled while being sandwiched between the end surface of the outer cylindrical portion 32 of the yoke 30 and the base 85. The base 85 includes a substantially rectangular bottom plate portion 86 having an opening 85 a and a plurality of column portions 87 provided at the corners of the bottom plate portion 86 at right angles to the bottom plate portion 86 and upward.

  The column portion 82 of the cover 80 and the column portion 87 of the base 85 are fitted to each other at corresponding positions. Thereby, at the time of assembly, the cover 80 and the base 85 can be bonded in a state where they are easily positioned.

  As shown in FIG. 14, three substantially triangular convex portions 201 are provided on the inner edge of the opening 80 a of the cover 80. The three substantially triangular convex portions 201 are arranged so as to be fitted to the three substantially triangular concave portions 72 provided on the outer edge of the stopper 70 with a gap. Thereby, the rotation of the holder 10 bonded to the stopper 70 in the circumferential direction can be restricted. Accordingly, during assembly, the lens assembly 100 can be easily attached to the holder 10 without causing problems such as plastic deformation of the connecting portion 63 of the leaf spring 60, peeling of the adhesion surface between the members, and breakage of the drawing portion 21 of the coil 20. Can be screwed together.

  In addition, a protruding portion 202 that protrudes inward in the radial direction from the opening 80 a is provided above the outer edge of the stopper 70. For example, when a large force is applied to the holder 10 due to an impact such as a drop, the protrusion 202 abuts against the stopper 70 to limit the displacement of the holder 10. Thereby, the plastic deformation of the connection part 63 of the leaf | plate spring 60 which supports the holder 10, peeling of the adhesion surface between members, the fracture | rupture of the drawer | drawing-out part 21 of the coil 20, etc. can be prevented.

  As shown in FIG. 2, the bottom plate portion 86 of the base 85 is provided with an insertion hole 88 through which the extension portion 92 of the sheet-like electrode 90 is inserted during assembly.

  Further, as shown in FIG. 2, three protrusions 89 are provided at an equal interval in the circumferential direction of the opening 85a and are integrally provided with the bottom plate portion 86 of the base 85 (see FIG. 3). In the assembled state, for example, the tip abuts against the lower surface of the flange portion 12 of the holder 10. The height of the protrusion 89 is longer than the distance from the upper surface of the bottom plate portion 86 of the base 85 to the lower leaf spring 60L. Therefore, the holder 10 is displaced upward. As a result, downward elastic force acts on the leaf springs 60U and 60L supporting the holder 10, and the back tension is always applied to the holder 10.

  Further, as shown in FIG. 2, the bottom plate portion 86 of the base 85 is provided with three circular holes 86a at substantially equal intervals in the circumferential direction of the opening 85a. The state of the soldering portion 22 on the sheet-like electrode 90 can be inspected from the outside of the base 85 through the circular hole 86a.

The assembly procedure of the above autofocus actuator will be described below.
[1] The coil 20 is fixed to the step 12a on the upper surface of the flange portion 12 of the holder 10 with an adhesive.
[2] Next, the four permanent magnets 40 are positioned at predetermined positions on the magnet mounting surface 33 on the inner peripheral surface of the outer cylindrical portion 32 of the yoke 30, and then fixed with an adhesive. In this state, the magnetic member 50 is attracted to the lower end surfaces of these permanent magnets 40 and fixed with an adhesive.
[3] Next, the holder 10 to which the coil 20 is fixed and the yoke 30 to which the above magnetic member 50 is attached are assembled. At this time, the cylindrical portion 11 of the holder 10 is inserted into the insertion hole 35 of the inner cylindrical portion 31 of the yoke 30. Further, the holder 10 and the yoke 30 are arranged so that the coil 20 is accommodated in a space between the outer peripheral surface of the inner cylindrical portion 31 of the yoke 30 and the permanent magnet 40.
[4] In the state [3], the upper and lower step portions 15 and 16 of the holder 10 are fitted with the inner ring portions 61 of the upper leaf spring 60U and the lower leaf spring 60L, respectively, and fixed with an adhesive.
[5] The stopper 70 is fixed to the upper surface of the upper leaf spring 60U bonded in [4] with an adhesive while the inner ring portion 61 of the upper leaf spring 60U is sandwiched between the upper surface of the cylindrical portion 11 and the upper surface. .
[6] The ring-shaped portion 91 of the sheet-like electrode 90 is bonded to the outer ring portion 62 of the lower leaf spring 60L bonded in [4] via an adhesive layer.
[7] The lead portion 21 and the dummy wire 23 of the coil 20 are wound around the protrusion 13 of the holder 10. Next, the leading ends of the lead portion 21 and the dummy wire 23 are soldered to the terminal portion 93 and the dummy terminal portion 95 of the sheet-like electrode bonded in [6]. Further, a stress relaxation agent 24 is applied to the portion wound around the protrusion 13 and the soldering portion 22.
[8] The cover 80 and the base 85 are attached to the parts assembled up to [7] so that the outer ring portion 62 of the upper leaf spring 60U and the lower leaf spring 60L is sandwiched between the yoke 30 and the upper leaf spring 60U. Next, the outer ring portion 62 of the upper leaf spring 60 </ b> U is bonded to the yoke 30 and the cover 80 between the yoke 30 and the cover 80. Further, the outer ring portion 62 of the lower leaf spring 60 </ b> L is bonded to the lower end surface of the outer cylindrical portion 32 of the yoke 30 and the base 85 between the lower end surface of the outer cylindrical portion 32 of the yoke 30 and the base 85. At this time, the extending portion 92 of the sheet electrode 90 is extended to the outside through the insertion hole 88 of the base 85.
[9] The lens assembly 100 is screwed into the holder 10 which is a part of the parts assembled up to [8].

Hereinafter, the operation of the autofocus actuator 1 will be described.
In FIG. 3, the direction of the magnetic field is from the permanent magnet 40 to the inner cylindrical portion 31 of the yoke 30. When a current flows counterclockwise when the coil 20 is viewed from above with the holder 10 in the initial position, an upward electromagnetic force is generated in the coil 20, that is, the holder 10. The holder 10 is displaced until the electromagnetic force and the elastic force of the leaf spring 60 that changes according to the displacement of the holder 10 are balanced. Since the electromagnetic force is controlled by the amount of current supplied to the coil 20, the holder 10, that is, the lens assembly 100 can be displaced to an arbitrary position by adjusting the amount of current supplied. In the autofocus actuator 1, the position information of the lens assembly 100 obtained from the amount of current supplied to the coil 20 and an image detected by a detection element (not shown) located below the autofocus actuator 1. Information. The position information and the image information are calculated at high speed by a calculation unit having a predetermined autofocus algorithm, thereby specifying the autofocus position of the lens assembly 100. By controlling the current supply to the coil 20 based on the result, the autofocus actuator 1 can realize autofocus.

  Hereinafter, a preferred embodiment of an autofocus actuator according to the present invention will be described in detail with reference to FIGS. 15 to 17. The present invention is obtained by improving the yoke and the plurality of permanent magnets 40 of the autofocus actuator 1 described in FIGS. 1 to 14, and the configuration of the actuator described above is applied to other configurations. Note that this is done. Therefore, description will be made with the aid of the constituent members of the autofocus actuator 1 described in FIGS. 1 to 14 as necessary.

  In the autofocus actuator 1 shown in FIGS. 1 to 14 described above, the yoke 30 has a cylindrical shape. Accordingly, the permanent magnet 40 also has a shape curved in an arc shape corresponding to the shape of the yoke 30. However, such a permanent magnet 40 is expensive and requires a special jig for positioning these magnets with respect to the yoke 30, resulting in a complicated manufacturing process.

  In view of such a problem, the present inventors have devised a yoke in which a rectangular parallelepiped, that is, a flat permanent magnet can be used, and the positioning and assembly of the permanent magnet are easy. As a preferred embodiment of such a yoke, there is a yoke 300 whose outer cylinder portion 302 has a substantially square cross section as shown in FIG.

  As shown in FIG. 15, four magnet attachment surfaces 303 are provided on the inner peripheral surface of the outer cylindrical portion 302. In this yoke 300, four substantially flat permanent magnets 41 that can be easily manufactured can be attached while being attracted to the magnet attachment surface 303.

  Further, as shown in FIG. 15, concave portions 304 that are recessed inward are formed at the four corners of the outer cylindrical portion 302. The distance between the inner surfaces of two adjacent recessed portions 304 on both sides of one magnet mounting surface 303 is substantially equal to the width of the substantially flat permanent magnet 41. Therefore, the inner surface of the recessed portion 304 can be easily positioned by contacting the side surface of the substantially flat permanent magnet 41.

  The substantially flat permanent magnet 41 is magnetized so that, for example, the back surface in contact with the magnet mounting surface 303 is an S pole and the surface facing the back surface is an N pole. These substantially flat permanent magnets 41 are attached to a substantially square yoke 300. Thereby, the outer peripheral surface of the inner cylinder part 301 becomes a south pole, and the magnetic field which goes to the inner cylinder part 301 from the substantially flat permanent magnet 41 is formed.

  Further, in the present embodiment, the inner cylindrical portion 301 of the substantially square yoke 300 is also formed to have a substantially square cross section. A coil accommodated at a predetermined interval from the inner cylindrical portion 301 and the substantially flat permanent magnet 41 is also used which is wound in a substantially square shape. Thereby, since the direction of the current flowing through the coil and the direction of the magnetic field formed inside the substantially square-shaped yoke 300 are substantially perpendicular, a sufficient driving force can be obtained. In the present embodiment, the coils are not limited to those wound in a substantially square shape as described above. For example, a coil having another cross-sectional shape that allows a driving force to be obtained in the optical axis direction when the coil is housed and displaced in a space of a predetermined interval in the yoke 300 and the coil does not contact other members may be used. .

  When such a substantially square-shaped yoke 300 is used, as shown in FIG. 17, each of the outer edges of the four corners has a substantially rectangular ring shape in which concave portions that are recessed inward are formed. A magnetic member 51 is used. The width of the portion other than the recessed portion is equal to the thickness of the substantially flat permanent magnet 41.

  Further, as another embodiment of the yoke in which flat permanent magnets can be used and positioning and assembling of the permanent magnets are easy, as shown in FIG. 16, the cross section of the outer cylindrical portion 312 has a substantially hexagonal shape. There is a yoke 310.

  In this embodiment, as shown in FIG. 16, six magnet mounting surfaces 313 are provided on the outer cylinder portion 312 of the yoke 310. In the yoke 310, the substantially flat permanent magnets 42 that can be easily manufactured can be attached while being attracted to the magnet attachment surface 313.

  Further, as shown in FIG. 16, in the yoke 310, a magnet mounting surface 313 is provided so that a part of the adjacent substantially flat permanent magnets 42 are in contact with each other. Thereby, the six substantially flat permanent magnets 42 attached to the magnet attachment surface 313 can be easily positioned.

  The substantially flat permanent magnet 42 is magnetized so that, for example, the back surface in contact with the magnet mounting surface 313 is an S pole and the surface facing the back surface is an N pole. These permanent magnets 42 are attached to a substantially hexagonal yoke 310. Thereby, the outer peripheral surface of the inner cylinder part 311 becomes a south pole, and the magnetic field which goes to the inner cylinder part 311 from the permanent magnet 42 is formed.

  Furthermore, in this embodiment, the inner cylinder portion 311 of the substantially hexagonal yoke 310 is formed in a substantially circular cross section. Therefore, the coil accommodated at a predetermined interval from the inner cylindrical portion 311 and the substantially flat permanent magnet 42 can also be used that is wound in a substantially circular shape. Further, since the permanent magnet 42 is attached in a substantially hexagonal shape that is nearly circular, a sufficient driving force can be obtained even if a substantially circular coil is used.

  When such a substantially hexagonal yoke 310 is used, a hexagonal ring-shaped magnetic member is used as the magnetic member described above. The width of the hexagonal ring-shaped magnetic member is equal to the thickness of each permanent magnet 42.

  According to the autofocus actuator according to the preferred embodiment of the present invention described above, since a substantially flat permanent magnet can be used, the permanent magnet processing step can be omitted, and the component cost can be reduced. it can. Further, when the permanent magnet is arranged on the yoke, the substantially flat permanent magnet can be easily positioned without using a positioning jig or a magnet support.

  Finally, it goes without saying that the present invention is not limited to the above-described preferred embodiments, and various improvements and modifications can be made within the scope of the following claims.

It is a perspective view of the appearance of an autofocus actuator according to the proposal of the present inventor. FIG. 2 is an exploded perspective view of the autofocus actuator shown in FIG. 1. FIG. 2 is a schematic cross-sectional view of the autofocus actuator shown in FIG. 1. It is a perspective view which shows a cylindrical yoke. It is sectional drawing of a yoke, Comprising: The mode of a magnetic field at the time of attaching only a permanent magnet is shown. It is sectional drawing of a yoke, Comprising: The mode of the magnetic field at the time of attaching a permanent magnet and a magnetic member is shown. It is a perspective view which shows a circular ring-shaped magnetic member. It is a top view of a leaf | plate spring. It is a top view of a sheet-like electrode. It is a part of schematic sectional drawing of the actuator for autofocus, Comprising: The state which connected the drawer | drawing-out part of the coil to the sheet-like electrode is shown. It is the elements on larger scale of A in FIG. It is a top view which shows the positional relationship of the flange part of a holder, the drawer part of a coil, and a sheet-like electrode. It is a top view of a stopper. It is a top view which shows the positional relationship of the opening part of a cover, and a stopper. It is a perspective view of the substantially square yoke which concerns on suitable embodiment of this invention, Comprising: The state which attached the substantially flat permanent magnet is shown. It is a perspective view of the substantially hexagonal yoke which concerns on another suitable embodiment of this invention, Comprising: The state which attached the substantially flat permanent magnet is shown. It is a perspective view which shows a substantially square ring-shaped magnetic member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Autofocus actuator 10 Holder 11 Cylindrical part 12 Flange part 12a Step part 13 Projection 14 Concave part 15 Convex part (Step part)
16 Step part 20 Coil 21 Lead part 22 Solder part 23 Dummy wire 24 Stress relaxation agent 30 Yoke 31 Inner cylinder part 32 Outer cylinder part 33 Magnet attachment surface 34 Connection part 35 Insertion holes 40-42 Permanent magnets 50 and 51 Magnetic member 60 Leaf spring 60U Upper leaf spring 60L Lower leaf spring 61 Inner ring portion 62 Outer ring portion 63 Connection portion 65 Recessed portion (outer edge)
66 recess (inner edge)
70 Stopper 71 Opening 72 Recess 80 Cover 80a Opening 81 Top Plate 82 Column 85 Base 85a Opening 86 Bottom Plate 86a Circular Hole 87 Column 88 Insertion Hole 89 Projection 90 Sheet Electrode 91 Ring Part 92 Extension 93 Terminal part 94 Cover film 95 Dummy terminal part 100 Lens assembly 201 Convex part 202 Projection part 300 Yoke 301 Inner cylinder part 302 Outer cylinder part 303 Magnet attachment surface 304 Recessed part 310 Yoke 311 Inner cylinder part 312 Outer cylinder part 313 Magnet attachment surface

Claims (7)

A holder having a cylindrical portion with a lens attached to one end;
A coil provided so as to be located around the cylindrical portion of the holder;
A pair of leaf springs provided on both sides in the optical axis direction of the cylindrical portion of the holder, and supported so as to be displaceable in the optical axis direction with the holder positioned in a radial direction;
A plurality of permanent magnets opposed to the coil, and the lens attached to the holder is moved in the optical axis direction by the interaction between the magnetic field generated in the coil by energizing the coil and the magnetic field of the permanent magnet. A yoke for enabling position adjustment,
The yoke is a cylinder having a substantially square cross section, which has an inner cylinder part through which the cylindrical part of the holder is inserted, and a predetermined interval on the outer side of the inner cylinder part, and has four corners and four inner surfaces. An outer cylinder part formed in a shape, and a connecting part in which the inner cylinder part and the lens-side end of the outer cylinder part are integrally connected, and the four inner surfaces of the outer cylinder part are respectively and flat-shaped magnet attachment surface, the result permanent magnets of four substantially flat permanent magnets are arranged on the magnet attachment surface,
All four corners of the outer cylindrical portion of the yoke are recessed inward, and a positioning surface that matches the size of the substantially flat permanent magnet is formed on each side of the magnet mounting surface. autofocus actuator, characterized in that is. The inner cylindrical portion of the yoke is formed in a substantially square section claims was wound cylindrical coils substantially square shape so as to be arranged at a predetermined interval the coil around the inner cylindrical portion Item 2. The autofocus actuator according to Item 1 . The autofocus actuator according to claim 1, further comprising magnetic flux leakage prevention means for preventing leakage of magnets from the four permanent magnets provided in the yoke. 4. The autofocus according to claim 3, wherein the magnetic flux leakage prevention means is a magnetic member disposed so as to connect the permanent magnets in contact with the surfaces of the four permanent magnets provided on the yoke. Actuator. The magnetic member has a thickness such that a surface on a side opposite to a surface in contact with the four permanent magnets is positioned closer to a connecting portion side of the yoke than an end surface of an outer cylindrical portion of the yoke. Item 5. The autofocus actuator according to Item 4. A holder having a cylindrical portion with a lens attached to one end and a flange portion provided on the outer periphery of the other end of the cylindrical portion;
A coil provided on the flange portion so as to be positioned around the cylindrical portion of the holder;
An inner cylinder part forming an insertion hole through which the cylindrical part of the holder is inserted, and a cylinder having a substantially square cross section, which is located at a predetermined interval on the outer side of the inner cylinder part and has four corners and four inner surfaces And an outer cylinder part formed in a shape, and a connecting part in which the inner cylinder part and the lens side end of the outer cylinder part are integrally connected, and the coil is accommodated in the space of the predetermined interval A yoke configured to:
Four substantially flat plate-like permanent magnets, which are respectively arranged so as to face the coil at a distance from the planar magnet mounting surfaces formed by the four inner surfaces of the outer cylindrical portion of the yoke;
A pair of leaf springs provided on both sides in the optical axis direction of the cylindrical portion of the holder, and supported so as to be displaceable in the optical axis direction with the holder positioned in a radial direction
Provided outside each of the pair of leaf springs, sandwiching the pair of leaf springs between both end surfaces in the optical axis direction of the yoke, and at least a portion corresponding to the lens attached to the holder, respectively An autofocus actuator comprising: a pair of support frames having openings; and allowing the position of a lens attached to the holder to be adjusted in the optical axis direction by energizing the coil.
All four corners of the outer cylindrical portion of the yoke are recessed inward, and a positioning surface that matches the size of the substantially flat permanent magnet is formed on each side of the magnet mounting surface. And
An autofocus actuator comprising a magnetic flux leakage prevention means for preventing magnetic flux leakage from an open portion opposite to the yoke coupling portion. 7. The autofocus according to claim 6, wherein the magnetic flux leakage prevention means is a magnetic member arranged to connect the permanent magnets in contact with the surfaces of the four permanent magnets provided on the yoke. Actuator.

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