JP4945787B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device that forms an image of a subject by driving a lens in the direction of an optical axis.

  In recent years, as camera-equipped mobile phones equipped with cameras have become popular, opportunities for photographing various subjects using the mobile phones have increased. For example, you can shoot a subject that is far away from the camera lens, such as a friend or landscape (normal shooting), or a subject that is close to the camera lens, such as a bus timetable or petals (close-up shooting) There is a case.

  In close-up photography (macro photography), the lens position of the camera needs to be slightly closer to the subject side than the lens position during normal photography. For this reason, this type of photographic lens system includes a drive mechanism that drives the lens to move in the direction of the optical axis, so that the lens can be moved in the direction of the optical axis by driving the drive mechanism by switching a switch. (For example, refer to Patent Document 1).

  The autofocus device disclosed in Patent Document 1 includes a cylindrical lens holder, a drive coil and a magnet that move the lens holder in the optical axis direction, and a holder spring that biases the lens holder in the optical axis direction. is doing. When the lens holder is moved, the position where the driving coil is energized and the driving force of the driving coil and the biasing force of the holder spring are balanced is the stationary position.

  On the other hand, when the drive coil is not energized (when the drive coil is not energized), the lens holder exists at an initial position (for example, a position closest to the image sensor within a movable range). In order to improve impact resistance such as preventing displacement, the lens holder is pressed in one direction by the urging force of the holder spring.

  Here, as a technique for pressing the lens holder in one direction when the drive coil is not energized, there is a technique using a magnetic member in addition to the technique using the biasing force of the holder spring described above. More specifically, for example, as shown in FIG. 10, a sleeve 101 that moves in the optical axis direction, a coil 102 that is attached to the sleeve 101, a magnet 103 that is disposed so as to face the coil 102, and a coil 102. In the lens driving device 100, which includes a leaf spring 104 that generates an urging force in a direction opposite to the driving force and a magnetic member 105 that is disposed so as to face the magnet 103 with the coil 102 interposed therebetween, The sleeve 101 is pressed in one direction (downward in FIG. 10) by utilizing the attractive force acting between the magnetic member 105 and the magnet 103 when no power is supplied (an offset force is applied). ing).

Japanese Patent Laying-Open No. 2005-165058

  However, in the lens driving device 100 shown in FIG. 10, since the magnetic member 105 and the magnet 103 are close to each other, the center axis of the sleeve 101 may be shifted to one side when the actuator is assembled. In this case, a radial force acts on the direction in which the central axis is deviated, which may adversely affect the initial tilt or the change tilt (for example, when the tilt characteristic is deteriorated, a focus deviation occurs).

  The present invention has been made in view of the above points, and an object thereof is to provide a lens driving device capable of improving tilt characteristics.

  In order to solve the above problems, the present invention provides the following.

(1) A movable body that holds a lens, a drive mechanism that moves the movable body in the optical axis direction, a fixed body on which the movable body and the drive mechanism are mounted, and the movable body and the fixed body. And a spring member that is attached so that the movable body is movable in the optical axis direction and biases the movable body in the optical axis direction. In the lens driving device including a coil attached to the coil and a magnet disposed so as to face the coil, the moving body is caused by an attractive force acting between the magnet when the coil is not energized. A magnetic member that regulates the displacement of the movable body, and the magnetic member is attached to an end surface of the movable body so as to be interposed between the movable body and the spring member, and is arranged to push up the spring member , Coil At the time of no energization, together with the attractive force acting between the magnetic member and the magnet, a force in the optical axis direction that is the same as the attractive force is applied to the spring member by pushing up the magnetic member. A lens driving device.
(2) The spring member is attached to the movable body side via an arm portion, and the magnetic member is disposed so as to push the arm portion up to the subject side, and when the coil is not energized, A lens driving device characterized in that, together with the attraction force acting between a magnetic member and the magnet, the moving member is pressed against the object side by the spring member.

  According to the present invention, the lens driving device has a moving body and a driving mechanism, and the driving mechanism includes a coil and a magnet. In addition, a magnetic member that restricts the variation of the moving body is provided by the magnetic attractive force acting between the magnet when the coil is not energized, and this magnetic member is arranged on the end face of the moving body. The distance between the magnetic member and the magnet can be increased to some extent.

That is, for example, in the lens driving device shown in FIG. 10 described above, the magnet is disposed on the side closer to the subject (upper side in FIG. 10) when the surface including the end surface closest to the subject is used as a reference. The distance between the member and the magnet can be increased. As the lens driving device, for example, not only a lens driving device of the type shown in FIG. 10 in which a coil and a magnet are opposed in the optical axis direction (a type in which a magnet is interposed between two coils), but also a coil and a magnet are used. Even in the type that faces in the radial direction (the type in which the outer peripheral surface of the coil and the inner peripheral surface of the magnet face each other), the coil should be placed on the side closer to the subject when the surface including the end face closest to the subject is used as a reference. Thus, the distance between the magnetic member and the magnet can be increased. As a result, it is possible to prevent the magnetic attractive force between the magnetic member and the magnet from becoming too strong, to prevent the center axis of the moving body from shifting, and to improve the tilt characteristics.

  In the conventional lens driving device, in order to more surely prevent the displacement of the moving body, the magnetic member is generally designed as close as possible to the magnet. However, in the lens driving device according to the present invention, in consideration of improvement in tilt characteristics, the magnetic member is prevented from being too close to the magnet, and the magnetic attractive force between the magnetic member and the magnet is prevented from becoming too strong.

  Here, the “magnetic member” that regulates the displacement of the moving body may be any shape, size, or material. For example, it may be ring-shaped or spherical. The ring-shaped one may be connected to one or may not be connected to one. Therefore, for example, when a spring member that biases the moving body in the optical axis direction is provided, it may be on the image sensor side or on the subject side as viewed from the spring member.

  The “magnetic member” regulates the displacement of the moving body by the magnetic attractive force acting between the magnet when the coil is not energized, but the coil is not particularly limited when energized. Any action may work. For example, when the coil is energized, an urging force may be applied to the moving body together with the spring member described above. Further, the “subject” in the present invention refers to a subject at a position where the reflected light is incident on the lens.

Has a spring member for biasing the pre-Symbol mobile in the optical axis direction, the magnetic member has a feature in that while being disposed on the end face of the movable body, interposed between said moving member and the spring member you.

  According to the present invention, the above-described spring member is provided in the lens driving device, and the magnetic member is disposed on the end surface of the moving body and interposed between the moving body and the spring member. It can be easily fixed (by interposing between the moving body and the spring member, it is possible to prevent wobbling in the optical axis direction).

  Further, according to the present invention, since the magnetic member is disposed on the image pickup element side when viewed from the spring member, it is possible to prevent the magnetic member from being separated from the magnet too much, so that the magnetic member works between the magnetic member and the magnet. It is possible to prevent the magnetic attractive force from becoming too weak. As a result, the tilt characteristics can be improved while maintaining the stability of the moving body when the coil is not energized.

  Here, the “end surface of the moving body” may be a planar end surface or an uneven end surface. That is, for example, a groove or a hole is provided on the end face of the moving body, and the bottom face of the groove or hole can also be an “end face” here.

  (3) A lens driving device, wherein a groove is formed on an end surface of the movable body, and the magnetic member is disposed by being fitted in the groove.

  According to the present invention, since the magnetic member described above is disposed by being fitted in the groove formed on the end surface of the movable body described above, the magnetic member can be more easily fixed (the magnetic member Positioning becomes easier).

  Further, when the subject-side end face of the moving body is too far away from the magnet, the magnetic attractive force between the magnetic member and the magnet can be adjusted by adjusting the depth of the groove.

  (4) The lens driving device, wherein the magnetic member is formed with a plurality of (magnetic attraction force) adjusting portions for adjusting a magnetic attraction force acting between the magnet and the magnet.

  According to the present invention, the magnetic member is provided with a plurality of (magnetic attraction force) adjusting portions for adjusting the magnetic attraction force acting between the magnet and the magnet. The magnetic attractive force between the magnetic member and the magnet (in any direction) can be adjusted by adjusting the position where the magnetic attractive force) adjusting portion is formed.

  According to the lens driving device of the present invention, by increasing the distance between the magnetic member and the magnet to some extent, it is possible to prevent the attractive force acting between them from becoming too strong, and to improve the tilt characteristics.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Overview]
FIG. 1 is a diagram showing an outline of a lens driving device 1 according to an embodiment of the present invention.

  In FIG. 1, the lens driving device 1 includes a moving body 3 that moves in the optical axis direction, a first driving coil 141 (not shown in FIG. 1) and a second driving coil 142 that are attached to the moving body 3. The magnet 17 disposed so as to face the drive coils 141 and 142 and the biasing force in the direction opposite to the driving force of the drive coils 141 and 142 are generated to bias the moving body 3 in the optical axis direction. Between the first plate spring 31 (not shown in FIG. 1) and the second plate spring 32 as spring members and the magnet 17 when the first drive coil 141 and the second drive coil 142 are not energized. And a magnetic member 138 that restricts the displacement of the moving body 3 by the magnetic attraction force acting on (in FIG. 1, presses the moving body 3 downward).

  Here, in the lens driving device 1 according to the present embodiment, the arrangement position of the magnetic member 138 is characteristic. That is, as shown in FIG. 1, the magnetic member 138 is disposed on the subject 3 (upper side in FIG. 1) end surface of the moving body 3 and is interposed between the moving body 3 and the second leaf spring 32. It is arranged to do. In other words, the magnetic member 138 has a subject when the surface including the end surface closest to the subject (that is, the front end surface of the second coil 142) of the first drive coil 141 and the second drive coil 142 is used as a reference. Is located on the side close to the subject (upper side in FIG. 1), and also on the side close to the subject (upper side in FIG. 1) when the surface of the magnet 17 including the end face closest to the subject is used as a reference. Has been.

  As a result, the distance between the magnetic member 138 and the magnet 17 can be increased to some extent, and the attractive force between the magnetic member 138 and the magnet 17 can be prevented from becoming too strong. As a result, it is possible to prevent the center axis of the moving body 3 from being shifted and thus improve the tilt characteristics.

  In addition, the magnetic member 138 being disposed on the lower surface of the leaf spring 32 (the lower side in FIG. 1) means that the magnetic member 138 is applied to the lower surface of the inner frame 320 of the leaf spring 32 (see FIG. 2). It shows that the member 138 is arranged. As a result, the magnetic member 138 pushes the inner frame 320 up to the subject side (the arm portions 325a to 325d of the leaf spring 320 are pushed up to the subject side) when no power is supplied, and the sleeve 15 moves in one direction (downward). Is holding down. That is, because the sleeve 15 is pressed downward by the interaction between the magnetic member 138 and the magnetic member 138 (because of an offset force), the lens driving device 1 is directed in any direction. The displacement of the sleeve 15 can be prevented. Hereinafter, the mechanical configuration and basic operation of the lens driving device 1 according to the present embodiment will be described in detail.

[Machine configuration]
FIG. 2 is a diagram illustrating a mechanical configuration of the lens driving device 1 according to the embodiment of the present invention. FIG. 2A is an external view of the lens driving device 1 when viewed obliquely from above, and FIG. 2B is an exploded perspective view of the lens driving device 1. 3 is a cross-sectional view of the lens driving device 1 shown in FIG. 2A when cut in the optical axis direction L at the position FF ′.

  2 and 3, the lens driving device 1 causes the three lenses 121, 122, and 123 to be opposite to the subject in the A direction (front side) approaching the subject (imaging target) along the optical axis direction L. It moves in both directions in the B direction (rear side) approaching the side (image side) (see FIG. 3), and has a rectangular parallelepiped shape (see FIG. 2A). Further, the lens driving device 1 includes a moving body 3 that integrally holds three lenses 121, 122, 123 and a fixed diaphragm 124 on a cylindrical lens holder 12, and the moving body 3 along the optical axis direction L. And a fixed body 2 as a support on which the lens driving mechanism 5 and the moving body 3 are mounted. The movable body 3 includes a cylindrical sleeve 15, and a cylindrical lens holder 12 is fixed to the inside of the movable body 3.

  The fixed body 2 includes a rectangular base 19 for holding an image sensor (not shown) on the image side, a rectangular case 11 positioned on the subject side, and a plate-shaped plate cover that covers the subject side of the case 11. 18, circular incident windows 110 and 180 are formed in the center of the case 11 and the plate-like cover 18 for taking reflected light from the subject into the lens. The fixed body 2 further includes a square tube-like back yoke 16 sandwiched between the base 19 and the case 11, and the back yoke 16, together with a drive magnet (magnet) 17 described later, is a drive coil (coil). ) 141 and 142 constitute a linkage magnetic field generator 4 for generating a linkage magnetic field.

  The lens drive mechanism 5 includes an annular first drive coil 141, a second drive coil 142, and an interlinkage magnetic field generator 4 arranged in two stages in the optical axis direction on the outer peripheral surface of the sleeve 15. Thus, the magnetic drive mechanism 5a is configured (see FIG. 3). The interlinkage magnetic field generator 4 includes four drive magnets 17 opposed to the drive coils 141 and 142 on the outer peripheral side, and a square cylindrical back yoke 16 made of a ferromagnetic plate such as a steel plate, The four drive magnets 17 are fixed to four corners on the inner peripheral surface of the back yoke 16.

  Each of the four drive magnets 17 is divided into two in the optical axis direction L, and in any case, the inner surface and the outer surface are magnetized to different poles. Further, in the four drive magnets 17, for example, the inner surface is magnetized to the N pole in the upper half, the outer surface is magnetized to the S pole, and the inner surface is magnetized to the S pole in the lower half, and the outer surface is the N pole. Is magnetized. The back yoke 16 is sandwiched between the base 19 and the case 11, and the back yoke 16 is exposed on the side surface of the lens driving device 1 and constitutes a side surface portion thereof.

  The lens driving mechanism 5 includes a first plate spring 31 sandwiched between the back yoke 16 and the base 19 and a second plate sandwiched between the back yoke 16 and the case 11. A spring 32 is provided. Both the first plate spring 31 and the second plate spring 32 are formed of a metal thin plate, and by making the thicknesses in the optical axis direction L the same, productivity can be improved.

  The back yoke 16 is larger than the dimension in the optical axis direction L of the region where the drive coils 141 and 142 are disposed and the dimension in the optical axis direction L of the drive magnet 17. Therefore, the leakage magnetic flux from the magnetic path configured between the drive magnet 17 and the first drive coil 141 and the magnetic path configured between the drive magnet 17 and the second drive coil 142 is reduced. can do. As a result, the linearity between the amount of movement of the sleeve 15 and the current flowing through the drive coils 141 and 142 can be improved. In the back yoke 16 in the present embodiment, for example, the above-described effect of reducing the leakage magnetic flux can be achieved without forming the shape of the back yoke 16 so as to cover the side surfaces, the lower surface, and the upper surface of the drive coils 141 and 142. Can be obtained.

  Furthermore, the lens driving device 1 includes an annular magnetic member 138 held at the upper end of the sleeve 15 (see FIG. 2B). In the present embodiment, the magnetic member 138 has a plurality of holes in the circumferential direction. These holes are adapted to engage with pins (projections) formed to fix the first plate spring 31 and the second plate spring 32. The magnetic member 138 applies a biasing force in the optical axis direction L to the moving body 3 by an attractive force acting between the magnetic magnet 138 and the driving magnet 17. For this reason, it is possible to prevent the movable body 3 from being displaced by its own weight when no power is supplied, and as a result, the movable body 3 can be maintained in a desired posture.

  In addition, the magnetic member 138 acts as a kind of back yoke, and a magnetic path configured between the drive magnet 17 and the first drive coil 141 and between the drive magnet 17 and the second drive coil 142. Leakage magnetic flux from the magnetic path constructed in (1) can be reduced.

  Furthermore, as described in [Overview], the magnetic member 138 is disposed on the subject side (front side) end face of the moving body 3 and is interposed between the moving body 3 and the second leaf spring 32. (Refer to FIG. 3).

  The back yoke 16 has a substantially rectangular outer peripheral shape, a pair of opposing side surface portions 161 are formed in a flat shape, and the other pair of opposing side surface portions 162 have both end portions 163 recessed inward. A convex portion 164 is formed at the center so as to project outward in a stepped shape. Therefore, when viewed from the optical axis direction L, in the back yoke 16, a rectangular region surrounded by the side surface portion 161 and both end portions 163 of the side surface portion 162 is a space where the leaf springs 31 and 32 can be disposed.

  The case 11 covers the subject side of the back yoke 16 and has a plate portion 115 in which an incident window 110 is formed at the center. At the four corners of the plate portion 115, a convex portion 111 extending toward the subject side and a convex portion 112 extending toward the imaging element side are formed, and a pair of opposing sides of the plate portion 115 is described later on the upper surface of the plate portion 115. A holding portion 113 that holds the circumferential direction of the engaging portion of the plate cover 18 is formed. Further, the base 19 is formed with convex portions 192 at the four corners extending toward the subject side, and columnar members 191 extend from the side surface toward the subject side. The convex portion 192 of the base 19 and the convex portion 112 of the case 11 are used when the leaf springs 31 and 32 are connected to the fixed body 2.

  The plate-like cover 18 is configured by a nonmagnetic thin plate (for example, SUS304), and covers the subject side of the case 11 and has a top plate portion 185 in which an incident window 180 is formed at the center. Although the top plate portion 185 has a substantially rectangular shape, rectangular cutouts 186 and 187 are formed in the vicinity of the four corners and the center of one side facing each other. A pair of engagement leg portions 181 extends downward from a pair of opposing side portions of the top plate portion 185. Further, in the other pair of opposite side portions of the top plate portion 185, a pair of engaging leg portions 182 extend downward from both ends near the notch 187, respectively. Each of the engaging legs 181 and 182 is formed with a through hole 183 in the vicinity of the central region thereof.

With the above configuration, when the plate cover 18 is overlaid with the base 19, the first plate spring 31, the second plate spring 32, and the case 11 being overlaid, the plate-like shape is formed on the holding portion 113 of the case 11. The plate-like cover 18 is disposed on the upper surface of the case 11 by fitting the notches 187 of the cover 18. At that time, the convex portions 111 formed at the four corners of the case 11 are disposed in the notches 186 formed at the four corners of the top plate portion 185. Further, the engaging leg portion 181 contacts the side surface portion 161 of the back yoke 16, and the engaging leg portion 182 contacts the side surface portion 162 of the back yoke 16 and is disposed so as to sandwich the convex portion 164. In the engaging leg portions 181 and 182 arranged in this way, for example, the side surface portions 161 and 162 and the engaging leg portions 181 and 182 are fixed by applying an adhesive from the through holes 183 included in each. The plate-like cover 18 can be fixed to the back yoke 16 by joining the side surface portions 161 and 162 and the engaging leg portions 181 and 182 by laser welding.

[basic action]
In the lens driving device 1 according to the present embodiment, the moving body 3 is normally located on the image sensor side (image side) (when the first driving coil 141 and the second driving coil 142 are not energized) (FIG. 3). Specifically, the lower end surface (image side surface) of the sleeve 15 is in contact with the upper surface (front side surface) of the base 19.

  Here, the magnetic member 138 regulates the displacement of the moving body 3 by the attractive force acting between the magnetic magnet 138 and the drive magnet 17. However, since the distance between the magnetic member 138 and the drive magnet 17 is maintained to some extent, the attractive force between the magnetic member 138 and the drive magnet 17 does not become too strong. As a result, the center axis of the moving body 3 is prevented from being displaced, and thus the tilt characteristics are prevented from deteriorating.

  In such a state, when a current in a predetermined direction is passed through the drive coils 141 and 142, the drive coils 141 and 142 receive an upward (front) electromagnetic force, respectively. As a result, the sleeve 15 to which the drive coils 141 and 142 are fixed starts to move toward the subject side (front side). At this time, an elastic force that restricts the movement of the sleeve 15 is generated between the leaf spring 31 and the front end of the sleeve 15 and between the leaf spring 32 and the rear end of the sleeve 15. For this reason, when the electromagnetic force that moves the sleeve 15 forward and the elastic force that restricts the movement of the sleeve 15 are balanced, the sleeve 15 stops. Further, when a current in the reverse direction is supplied to the drive coils 141 and 142, the drive coils 141 and 142 receive a downward (rear) electromagnetic force.

  At that time, the sleeve 15 (moving body 3) can be stopped at a desired position by adjusting the amount of current flowing through the drive coils 141 and 142 and the elastic force acting on the sleeve 15 by the leaf springs 31 and 32. It is to be noted that the magnetic drive mechanism 5a for generating a propulsive force in the optical axis direction L on the moving body 3 by utilizing the urging force of the magnetic member 138 held on the moving body 3 and the drive magnet 17 is also downsized. Can be done. Further, by stopping the sleeve 15 using a balance between electromagnetic force and elastic force, it is possible to prevent the occurrence of collision noise.

[Example]
FIG. 4 is a diagram illustrating a result of analyzing the attractive force (attractive force) acting on the magnetic member 138 when the magnetic member 138 and the magnet 17 are located close to each other.

  Here, as shown in FIG. 4A, the magnetic member 138 is divided into eight parts, and the radial direction (X direction and Y direction, components in the X direction cause tilt problems) and the optical axis direction (Z Direction) was analyzed. The analysis result is as shown in FIG.

  FIG. 4B shows a list of the force Fx [gf] acting in the X direction, the force Fy [gf] acting in the Y direction, and the force Fz [gf] acting in the Z direction with respect to each divided portion. When attention is paid to Fx, the absolute values are maximum at −0.32 and 0.32 respectively in “division 4” and “division 8” (see the asterisks in FIG. 4B). Further, if attention is paid to Fy, “Division 4” is 0.22 which is the maximum (see the mark “*” in FIG. 4B).

  In this analysis, since there is no center axis deviation, it can be seen that when the force Fy acting in the Y direction is added, it becomes almost zero. Further, as indicated by a star mark on the left side of the list, the “partition 1”, “partition 4”, “partition 5”, and “partition 8” have a great influence on suction in the X direction. Furthermore, below the list, it is shown that the magnetic attractive force (analysis value) of the magnetic member 138 is −1.27.

  On the other hand, FIG. 5 is a diagram showing another analysis result obtained by analyzing the magnetic attractive force acting on the magnetic member 138 by the drive magnet 17 in the lens driving device 1 according to the embodiment of the present invention. This (magnetic attraction force) adjusting part can also be used as an attaching part to the sleeve 15.

  Again, as shown in FIG. 5A, the magnetic member 138 is divided into eight parts, and the radial direction (X direction and Y direction; components in the X direction cause tilt problems) and the optical axis direction (Z Direction) was analyzed. The analysis result is as shown in FIG.

  FIG. 5B is a list similar to FIG. 4B, and when attention is paid to Fx, “divided 1”, “divided 4”, and “divided 8” are −0.15 or 0.15. In particular, “Division 5” has a maximum value of −0.16 (see the mark “*” in FIG. 5B). When attention is paid to Fy, the absolute values are maximum at 0.12 and −0.12 for “division 4” and “division 8”, respectively (see * in FIG. 5B).

  Similar to FIG. 4, the magnetic attraction force (analysis value) of the magnetic member 138 is shown to be −1.12 below the list.

  4B and 5B are compared, the attractive force in the X direction in FIG. 5B is approximately 1 than the magnetic attractive force in the X direction in FIG. It can be seen that it is reduced by about / 2 (about 0.32 → about 0.16). That is, it is considered that the magnetic attraction force in the X direction, which is one factor of the tilt change, is difficult to work even if the position shift of the central axis occurs due to product assembly variation. In the present embodiment, as shown in FIG. 5 (b), four (magnetic attraction force) adjusting portions 138a that are widely formed in the radial direction are formed at approximately equal intervals. It is good also as forming the (attraction force) adjustment part 138a (or less (magnetic attraction force) adjustment part 138a). Further, the shape and the formation position thereof are not limited.

FIG. 6 is a diagram illustrating an analysis result when the shape of the magnetic member 138 is changed. In this analysis, it was examined whether the magnetic attractive force in the X direction could be further reduced by changing the shape of the magnetic member 138. More specifically, two (magnetic attraction force) adjustment sections that are symmetrical among the (magnetic attraction force) adjustment sections 138a (all four positions) of the magnetic member 138 (wire spring) shown in FIG. In 138a, a portion protruding to the inner diameter side is cut (see FIG. 6B).
In the present embodiment, a hole is formed in the (magnetic attraction force) adjusting portion 138a. This hole is fitted to a pin (protrusion) formed on the end face of the sleeve 15 to fix the magnetic member 138.

  In this case, the suction force in the X direction decreased from 0.17 to 0.16. In addition, the magnetic attractive force in the X direction also decreased from 1.42 to 1.31. Thus, according to the magnetic member 138 shown in FIG. 6B, the magnetic attractive force in the X direction can be further weakened. In addition, the (magnetic attraction force) adjusting portions 138a to 138a shown in FIG. 4 or an annular magnetic member without a portion where the portion protruding to the inner diameter side is cut may be used.

[Effects of embodiment, etc.]
As described above, according to the lens driving device 1 according to the present embodiment, the magnetic attractive force between the magnetic member 138 and the driving magnet 17 is increased by separating the distance between the magnetic member 138 and the driving magnet 17 to some extent. It can prevent becoming too strong. As a result, it is possible to prevent the center axis of the moving body 3 from being shifted, and thus to improve the tilt characteristics.

  Further, since the magnetic member 138 is interposed between the movable body 3 and the second leaf spring 32, it can be prevented that the magnetic member 138 is displaced in the optical axis direction. Furthermore, as described in the embodiment with reference to FIG. 6, by changing the shape of the magnetic member 138, the magnetic attraction force in the X direction causing a tilt problem can be reduced, and as a result, the tilt characteristics can be improved. it can.

[Modification]
FIG. 7 is a diagram illustrating a state in which the magnetic member 138 is placed in the groove 15 a formed on the subject-side end surface of the moving body 3.

  As shown in FIG. 7, the magnetic member 138 can be disposed by being fitted in a groove 15 a formed in the moving body 3. Thereby, positioning of the magnetic member 138 becomes easy. Further, the magnetic attractive force between the magnetic member 138 and the drive magnet 17 can be adjusted by adjusting the depth of the groove 15a. Furthermore, the depth of the groove 15a may be deeper than the magnetic member 138, or may be shallow. For example, when the depth of the groove 15a is set so that the surface of the magnetic member 138 protrudes from the end face, the urging force corresponding to the protruding amount is applied to the leaf spring placed on the magnetic member 138. Can be loaded. That is, an offset force may be applied.

  FIG. 8 is a diagram illustrating a state in which the magnetic member 138 is disposed on the front side (the front side in FIG. 8) of the second leaf spring 32.

  As shown in FIG. 8, the magnetic plate 138 can also be disposed on the front side (the front side in FIG. 8) of the second leaf spring 32. Thereby, compared with the case where the magnetic member 138 exists in the back side of the 2nd leaf | plate spring 32, the magnetic attraction force with the drive magnet 17 can further be reduced.

  FIG. 9 is a diagram showing that the present invention can also be applied to a lens driving apparatus 1A of a type in which a driving magnet 17 is interposed between two driving coils 141 and 142. FIG. FIG. 9A is a diagram showing an outline of the lens driving device 1A described above.

  The present invention can also be applied to a case where a drive magnet 17 is interposed between two coils as shown in FIG. Specifically, in the lens driving device 1A, the magnetic member 138 includes a surface including the end surface closest to the subject (that is, the front end surface of the second coil 142) of the first driving coil 141 and the second driving coil 142. When S1 is used as a reference, it is arranged on the side close to the subject (the upper side in FIG. 9B), and also when the surface S2 including the end face closest to the subject among the drive magnets 17 is used as a reference. Are arranged on the side close to the subject (the upper side in FIG. 9B).

  Thus, in this invention, the drive magnet 17 may be arrange | positioned so that the drive coils 141 and 142 may be opposed to a radial direction (refer FIG. 1), and the drive coils 141 and 142 and an optical axis direction May be arranged so as to face each other (see FIG. 9).

  The lens driving devices 1 and 1A can be attached to various electronic devices in addition to the camera-equipped mobile phone. For example, PHS, PDA, bar code reader, thin digital camera, surveillance camera, vehicle rear view confirmation camera, door with optical authentication function, and the like.

  The lens driving device according to the present invention is useful as a device capable of improving the tilt characteristics.

It is a figure which shows the outline | summary of the lens drive device which concerns on embodiment of this invention. It is a figure which shows the mechanical structure of the lens drive device which concerns on embodiment of this invention. It is sectional drawing when the lens drive device shown to FIG. 2 (A) is cut | disconnected in the optical axis direction L in the position of FF '. It is a figure which shows the analysis result which analyzed the attraction force which acts on a magnetic member with a drive magnet in the lens drive device which concerns on the Example of this invention. It is a figure which shows another analysis result which analyzed the attractive force which acts on a magnetic member with a drive magnet in the lens drive device which concerns on the Example of this invention. It is a figure which shows the analysis result when changing the shape of a magnetic member. It is a figure which shows a mode that a magnetic member is fitted and arrange | positioned at the groove | channel formed in the to-be-photographed object side end surface among moving bodies. It is a figure which shows a mode that the magnetic member is arrange | positioned at the front side of the 2nd leaf | plate spring. It is a figure which shows that this invention is applicable also in the lens drive device of the type which a drive magnet interposes between two drive coils. It is a figure which shows the outline | summary of the conventional lens drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Fixed body 3 Moving body 5 Lens drive mechanism 11 Case 138 Magnetic member 141,142 Drive coil 15 Sleeve 16 Back yoke 17 Magnet (drive magnet)
18 Plate cover 19 Base

Claims (4)

A moving body that holds the lens;
A drive mechanism for moving the movable body in the optical axis direction;
A fixed body on which the movable body and the drive mechanism are mounted;
A spring member attached between the movable body and the fixed body so that the movable body is movable in the optical axis direction and biasing the movable body in the optical axis direction ;
In the lens driving device, the driving mechanism includes a coil attached to the moving body and a magnet arranged to face the coil.
A magnetic member that regulates displacement of the moving body by an attractive force acting between the magnet and the coil when no current is applied;
The magnetic member is attached to an end surface of the moving body so as to be interposed between the moving body and the spring member, and is arranged to push up the spring member . When the coil is not energized, the magnetic member A lens driving device characterized in that, together with the attraction force acting between the magnet and the magnet, a force in the optical axis direction that is the same as the attraction force is applied to the spring member by pushing up the magnetic member. . The spring member is attached to the movable body side via an arm portion,
The magnetic member is disposed so as to push up the arm portion toward the subject side, and when the coil is not energized, together with the attractive force acting between the magnetic member and the magnet, the moving member is moved by the spring member. The lens driving device according to claim 1, wherein the lens is pressed to a side opposite to the subject side. A groove is formed on the end surface of the moving body,
The lens driving device according to claim 2, wherein the magnetic member is disposed in the groove.   The lens drive according to any one of claims 1 to 3, wherein the magnetic member is formed with an adjusting portion for adjusting a magnetic attractive force acting between the magnet and the magnet. apparatus.