JP2011257705A - Lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive device that can be miniaturized in a direction perpendicular to a lens optical axis.SOLUTION: A lens drive device includes a base 10, a plurality of lenses 81 to 84 different in diameter, a holder 60 for holding the lenses 81 to 84 so as to be arranged in the direction of the optical axis, a magnet 70 fitted to the holder 60, and a coil 20 fitted to the base 10 so as to be opposed to the magnet 70. The magnet 70 is disposed on a position that is inner than the outer periphery of the lens 84 having the largest diameter and corresponds to the lenses 81 to 84 having small diameters.

Description

  The present invention relates to a lens driving device, and is particularly suitable for use in a lens driving device mounted on a camera module.

  Conventionally, a camera module is mounted on a mobile phone or the like. Such a camera module includes a lens driving device for focus adjustment. The lens driving device displaces the lens in the optical axis direction according to the control signal. Thereby, the focus adjustment with respect to the subject is performed.

  As one of the lens driving devices, a moving magnet type lens driving device is known (for example, Patent Document 1). In this type of lens driving device, a magnet is attached to a holder that holds a lens. The holder is supported so as to be displaceable in the optical axis direction of the lens with respect to the base. A coil is arranged on the base so as to face the magnet on the holder side. The holder is driven along with the magnet in the optical axis direction of the lens by an electromagnetic driving force generated by applying a current to the coil.

JP 2008-185749 A

  In the lens driving device, generally, a plurality of lenses are mounted on a cylindrical barrel, and the barrel is mounted on an opening of a holder. For example, a screw is formed on the outer periphery of the barrel, and a screw that meshes with the screw is formed in the opening of the holder. The lens is attached to the holder by engaging the two screws with each other and attaching the barrel to the holder.

  In this configuration, the magnet cannot be disposed inside the outer diameter of the barrel. For this reason, it is difficult to reduce the size of the lens driving device in the direction perpendicular to the lens optical axis.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a lens driving device that can be miniaturized in a direction perpendicular to the lens optical axis.

  A lens driving device according to a main aspect of the present invention includes a base, a plurality of lenses having different diameters, a holder for holding the lenses so that the lenses are aligned in the optical axis direction, and a magnet mounted on the holder. And a coil mounted on the base so as to face the magnet. Here, the magnet is disposed on the inner side of the outer periphery of the lens having the largest diameter and corresponding to the lens having a small diameter.

  According to this configuration, since the magnet is arranged inside the outer periphery of the lens having the largest diameter, the outer shape of the holder including the magnet can be reduced in a direction perpendicular to the lens optical axis. Therefore, the external dimensions of the entire lens driving device can be reduced.

As described above, according to the present invention, it is possible to provide a lens driving device that can be miniaturized in a direction perpendicular to the lens optical axis.

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example when the present invention is implemented, and the present invention is not limited to what is described in the following embodiment.

It is a disassembled perspective view which shows the structure of the lens drive device which concerns on embodiment. It is a figure which shows the structure of the base which concerns on embodiment. It is a figure which shows the structure of the holder which concerns on embodiment. It is a figure which shows the connection method of the coil with respect to the printed circuit board which concerns on embodiment. It is a figure which shows the assembly process of the lens drive device which concerns on embodiment. It is sectional drawing which shows the structure of the lens drive device which concerns on embodiment. It is a figure explaining operation | movement of the lens drive device which concerns on embodiment. It is a figure which shows the structure of the camera module which concerns on embodiment. It is a figure which shows the structure of the lens drive device which concerns on the example of a change of embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an exploded perspective view showing the configuration of the lens driving device. FIG. 1A is an exploded perspective view seen from the upper side, and FIG. 1B is an exploded perspective view seen from the lower side.

  1A and 1B, the lens driving device includes a base 10, a coil 20, two magnetic plates 30, a printed circuit board 40, a base cover 50, a holder 60, and a magnet 70. A lens group 80, a shaft 90, and a cover 100.

  The base 10 has a box shape with an open lower surface, and has a square shape with chamfered corners in plan view. A continuous coil 20 is wound around the base 10 in two stages. The winding direction of the coils 20 at each stage is opposite to each other. Magnetic plates 30 and 30 are bonded to the outer surface of the coil 20. A printed circuit board 40 is mounted on the side surface of the base 10. Two ends of the coil 20 are soldered to the printed board 40. A base cover 50 is attached to the lower surface of the base 10.

  The holder 60 is formed with a lens housing portion 61 for housing the lens group 80. The lens group 80 is accommodated in the lens accommodating portion 61 so that the optical axes coincide with each other. After the lens group 80 is attached to the lens housing 61, the lens housing 61 is closed from below by a filter (not shown). This filter is an infrared ray removing filter. The lens group 80 includes four lenses 81 to 84 having different diameters.

  The holder 60 is formed with four magnet mounting portions 64. These four magnet mounting portions 64 are arranged at intervals of 90 degrees around the optical axis of the lens group 80. Further, the distance from the optical axis of the lens group 80 to each magnet mounting portion 64 is the same. The magnets 70 are mounted on the magnet mounting portions 64, respectively.

  The four magnets 70 are, for example, sintered magnets made of neodymium or the like, and have a two-pole arrangement structure in which N and S are magnetized on one side. The size and magnetic strength of each magnet 70 are equal to each other. When the magnets 70 are respectively mounted on the four magnet mounting portions 64, the two magnets 70 are arranged symmetrically with respect to the optical axis of the lens group 80, and the remaining two magnets 70 are also relative to the optical axis of the lens group 80. Arranged symmetrically.

  The holder 60 is formed with holes 63 at diagonal positions. The shafts 90 are passed through these holes 63, and the holder 60 is supported so as to be displaceable in the optical axis direction of the lens. The shaft 90 is made of a metal member and has a circular cross section.

  The cover 100 has a square shape with chamfered corners in plan view. The outer shape of the cover 100 in plan view is substantially equal to the outer shape of the base 10. The shape of the inner surface of the cover 100 in plan view is substantially the same as the outer shape of the base 10 to which the coil 20 and the magnetic plates 30 and 30 are attached. The cover 100 is formed with an opening 101 through which light passes.

  FIG. 2A is a perspective view when the base 10 is viewed from above, and FIG. 2B is a perspective view when the base 10 is viewed from below.

  As shown in the figure, the base 10 is formed of a box-shaped member whose lower surface is opened. The base 10 is integrally formed as a single member by injection molding of a resin material. An opening 11 for inserting the holder 60 into the base 10 is formed on the lower surface of the base 10. In addition, an opening 12 through which the uppermost part of the holder 60 passes is formed on the upper surface of the base 10. Further, a hole 13 for inserting the shaft 90 is formed on the upper surface of the base 10 at a diagonal position.

  A cutout 14 for passing the magnet 70 is formed on each side surface of the base 10. Furthermore, a partition 15 for dividing the coil 20 into two upper and lower stages is formed on the side surface of the base 10.

  With reference to FIG. 2B, a recess 16 for mounting the printed circuit board 40 is formed on one side surface of the base 10. Two kerfs 17 are formed on the side surface where the recess 16 is formed. The right partition 15 in FIG. 2B is formed with a convex portion 15a that is one step higher. Further, two protrusions 18 protrude from the lower surface near the recess 16. Further, two depressions 19 are formed on the lower surface of the base 10.

  FIG. 3 is a diagram illustrating the configuration of the holder 60. 4A is a perspective view when the holder 60 is viewed from above, FIG. 4B is a perspective view when the holder 60 is viewed from below, and FIG. 4C is the perspective view of FIG. AA 'sectional drawing and the figure (d) are top views when the holder 60 is seen from the top.

  Referring to FIGS. 2A and 2B, the holder 60 is formed with a circular lens housing portion 61 for housing the lens group 80 from below. The lens housing portion 61 houses four lenses 81 to 84 (see FIG. 1A) having different diameters. The diameter of the lens accommodating portion 61 is gradually reduced according to the diameters of the lenses 81 to 84. In the lens accommodating portion 61, step portions 61a to 61d are formed at positions where the diameter changes. The diameter of the inner surface divided by the step portions 61a to 61d is substantially the same as the diameter of the corresponding lens. The lenses 81 to 84 are bonded and fixed to the step portions 61a to 61d, respectively. In this way, the holder 60 holds the four lenses so that they are arranged in order of increasing diameter from the light incident side.

  As shown in FIG. 6A, the outer surface of the holder 60 has a shape that substantially reflects the shape of the inner surface of the lens housing portion 61. That is, the outer surface of the holder 60 also has a diameter that gradually decreases toward the light incident side, like the inner surface of the lens housing portion 61. An opening 62 for allowing light to pass through is formed on the upper surface of the holder 60. In addition, a hole 63 for passing the shaft 90 is formed on the outer surface of the holder 60 at a diagonal position.

Further, the four magnet mounting portions 64 are formed on the outer surface of the holder 60 as described above. The magnets 70 are mounted on the magnet mounting portions 64, respectively. The magnet mounting portion 64 has an E shape when viewed from the side. When the magnet 70 is mounted on the magnet mounting portion 64, excess adhesive accumulates at the step 64 a between the top surface and the bottom surface of the magnet mounting portion 64.

  As shown in FIGS. 4A and 4C, the magnet mounting portion 64 is formed so as to ride on the lowermost step on the outer side surface of the holder 60. When the magnet 70 is mounted on the magnet mounting portion 64, the upper surface of the magnet 70 is higher than the second flat surface S2 from above the outer surface of the holder 60 and lower than the uppermost surface S1. Further, as shown in FIG. 4D, the four magnet mounting portions 64 are disposed on the inner side of the outermost peripheral surface of the holder 60. When the magnet 70 is mounted on the magnet mounting portion 64, the magnet 70 is positioned inside the diameter range Wd of the lens 84 having the largest diameter.

  The lens group 80 (see FIG. 1) includes four lenses 81 to 84 in order to properly irradiate the image sensor 200 with the light in the object region. The lens 81 is for taking in light in the object area and has a small curvature. The light in the subject area is taken in by the lens 81 and narrowed down to a small size. The lenses 82 to 84 gradually expand the light narrowed down by the lens 81 so as to match the size of the sensor area of the image sensor 200. The lenses 82 to 84 include lenses for suppressing light aberration. Based on such an optical action, the lens group 80 includes four lenses 81 to 84, and the diameters of these lenses 81 to 84 are different from each other.

  FIG. 4 is a perspective view showing a method for connecting the coil 20 to the printed circuit board 40.

  As shown in FIG. 4A, the printed circuit board 40 is fitted into the recess 16 and is fixed by adhesion. Next, as shown in FIG. 5B, the ends 20a and 20b of the coil 20 are wound around the left and right protrusions 18, respectively. The end 20 a is hooked on a convex portion 15 a provided on the partition 15, and further passed through the left kerf 17 and wound around the left protrusion 18. The end 20 b is passed through the right kerf 17 and wound around the right protrusion 18. Thereby, the end portions 20a and 20b come along the electrodes 40a and 40b of the printed circuit board 40. The end portions 20a and 20b are stripped of an insulating film.

  Thereafter, as shown in FIG. 3C, solder 21 is applied to the intersections of the end portions 20a, 20b and the electrodes 40a, 40b, and the end portions 20a, 20b and the electrodes 40a, 40b are connected to each other. Then, as shown in FIG. 4D, the two protrusions 18 are cut, and the end portions 20a and 20b on the protrusion 18 side from the solder 21 are further cut. Thus, the connection of the coil 20 to the printed board 40 is completed.

  At the time of assembly, as shown in FIGS. 1A and 1B, the magnet 70 is bonded and fixed to the magnet mounting portion 64 of the holder 60, and the lens group 80 is bonded and fixed to the lens housing portion 61. In addition, the coil 20 is attached to the base 10, and the magnetic plates 30 are bonded and fixed to the two side surfaces of the coil 20, respectively. Further, the printed circuit board 40 is bonded and fixed to the base 10 as described above, and the coil 20 is connected to the printed circuit board 40. FIG. 1B shows a state before the protrusion 18 is cut.

  Thereafter, the holder 60 to which the magnet 70 and the lens group 80 are attached is accommodated in the base 10 from below, and the base cover 50 is attached to the lower surface of the base 10.

The base cover 50 is formed with a step 51 having substantially the same shape as the opening 11 of the base 10 in plan view, and an opening 52 through which the lowest part of the holder 60 passes is formed in the step 51. Further, two holes 53 into which the shaft 90 is fitted are formed in the step portion 51 at diagonal positions. Further, the base cover 50 has a protrusion 5 that fits into the recess 19 on the lower surface of the base 10.
4 is formed.

  The base cover 50 is attached to the lower surface of the base 10 by fitting the two protrusions 54 to the two recesses 19 of the base 10 while fitting the stepped portion 51 to the opening 18 of the base 10. Further, an adhesive is applied to the joint between the base cover 50 and the base 10, and the base cover 50 is bonded and fixed to the base 10.

  When the base cover 50 is thus attached to the base 10, the two holes 13 of the base 10 and the two holes 53 of the base cover 50 are aligned in the optical axis direction of the lens group 80. In this state, one hole 63 of the holder 60 is positioned between the hole 13 and the hole 53, the shaft 90 is inserted from the hole 13, and the shaft 90 is pushed in until the lower end of the shaft 90 is inserted into the hole 53. Similarly, the other hole 63 of the holder 60 is positioned between the hole 13 and the hole 53, the shaft 90 is inserted from the hole 13, and the shaft 90 is pushed in until the lower end of the shaft 90 is inserted into the hole 53. Accordingly, the two shafts 90 are passed through the two holes 63 and the holder 60 is supported by these shafts 90. Since the diameters of the two holes 63 are larger than the diameter of the shaft 90, the holder 60 can move along the shaft 90 in the optical axis direction of the lens group 80.

  FIG. 5A is a diagram showing an assembled state when the shaft 90 is mounted. As shown in the figure, the holder 60 receives a force in the direction of the dotted line arrow in the figure by the magnetic force between the two magnetic plates 30 and the magnet 70. With this force, the hole 63 of the holder 60 is pressed against the shaft 90. Thereby, when the energization to the coil 20 is stopped, the holder 60 is held at the position when the energization is stopped.

  Thereafter, as shown in FIG. 5B, the cover 100 is attached to the base 10 from above. Thereby, the assembly of the lens driving device is completed.

  6A is a cross-sectional view taken along the line B-B ′ of FIG. 5B, and FIG. 6B is a cross-sectional view taken along the line C-C ′ of FIG. 5B. Moreover, FIG.6 (c) is an enlarged view of the right side part of Fig.6 (a). In the figure, the lens group 80 is not shown.

  As shown in FIG. 6B, the holder 60 is on the base cover 50 at the home position. From this state, the holder 60 can move along the shaft 90 in the upward direction of the figure. During this movement, the uppermost part of the holder 60 passes through the opening 12 of the base 10. The magnet 70 passes through the notch 14 of the base 10. As shown in FIG. 3C, a space S by the notch 14 exists on the magnet 70. When the holder 60 moves from the home position, the magnet 70 passes through the space S.

  FIG. 7 is a diagram illustrating the driving operation of the lens driving device. This figure is a diagram schematically showing the B-B 'cross section of FIG. In the figure, a black dot mark on the circle and a cross mark on the circle indicate the direction of current flow. A black dot mark on the circle indicates a direction toward the drawing reference person, and a cross mark on the circle indicates a direction away from the drawing reference person. In the same figure, the lenses 81 to 84 are schematically shown by broken lines.

As shown in the figure, the N pole region of the magnet 70 is opposed to the upper portion of the coil 20, and the S pole region of the magnet 70 is opposed to the lower portion. When a current in the direction shown in FIG. 7A flows through the coil 20, an upward driving force acts on the magnet 70, and the holder 60 is displaced upward in the figure. As a result, the holder 60 is displaced upward as shown in FIG. When the application of current is stopped in this state, the holder 60 is pressed against the shaft 90 by the magnetic force between the magnetic plates 30 and 30 and the magnet 70, and is held at the position when the current application is stopped. In the state shown in FIG. 7B, when a reverse current is applied to the coil 20, the holder 60 is displaced downward.

  In this way, the lens group 80 is positioned at the on-focus position by the holder 60 being displaced upward and downward. The home position of the holder 60 is a position where the holder 60 is placed on the base cover 50 as shown in FIGS.

  FIG. 8 is a diagram showing a schematic configuration of a camera module in which the lens driving device having the above configuration is mounted. In the figure, reference numeral 1 denotes a lens driving device.

  Below the base cover 50, a circuit board 200 on which the image sensor 201 is mounted is disposed. The base 10 is provided with a hall element 110 as a position sensor, and the position of the holder 60 is detected based on a signal from the hall element 110.

During the focusing operation, a CPU (Central Processing Unit) 301 controls the driver 302 to displace the holder 60 from the home position to a predetermined position in the optical axis direction of the lens. At this time, a position detection signal from the Hall element 110 is input to the CPU 301. At the same time, the CPU 301 processes a signal input from the image sensor 201 to acquire a contrast value of the captured image. Then, the position of the holder 60 having the best contrast value is acquired as the on-focus position.

  Thereafter, the CPU 301 drives the holder 60 toward the acquired on-focus position. At that time, the CPU 301 monitors the signal from the hall element 110 and drives the holder 60 until the signal from the hall element 110 reaches a state corresponding to the on-focus position. Thereby, the holder 60 is positioned at the on-focus position.

  As described above, according to the present embodiment, for example, as illustrated in FIG. 3, the space generated on the outer surface of the holder 60 by the lenses 81 to 83 having a small diameter is used to be inside the outer periphery of the lens 84 having the largest diameter. The magnet 70 is disposed. For this reason, the outer shape of the holder 60 including the magnet 70 can be reduced in the direction perpendicular to the optical axis of the lens group 80. Therefore, the external dimensions of the entire lens driving device can be reduced.

  Further, according to the present embodiment, for example, as shown in FIG. 5A, the upper portion of the holder 60 and the magnet 70 can be moved by the opening 12 and the notch 14. It is not necessary to provide a gap according to the movement stroke of the holder 10 and the magnet 70 between the uppermost part of the magnet and the inner surface of the upper part of the magnet 70 and the base 10. Therefore, the dimension of the base 10 in the height direction can be reduced, and the outer dimensions of the entire lens driving device can be reduced.

  Further, according to the present embodiment, since the four magnets 70 are arranged at positions symmetrical to the optical axis of the lens group 80, a stable driving force can be applied to the holder 60.

  Further, since the base 10 has a box shape having the opening 11 at the bottom, the holder 60 to which the lens group 80 and the magnet 70 are attached can be easily accommodated in the base 10 from the opening 11. Furthermore, by attaching the base cover 50 to the opening 11, the holder 60 can be regulated in the base 10, and in this state, by attaching the shaft 90, the holder 60 can be supported with respect to the base 10. Thus, according to the present embodiment, the assembly operation of the lens driving device can be simplified.

In the present embodiment, since the holder 60 is inserted into the base 10 from the opening 11, as shown in FIG. 2A, the upper part of the base 10 is connected by the top surface. For this reason, the upper part of the base 10 has high mechanical strength, and even if the coil 20 is wound on the side surface, it does not bend inward. Since the hole 13 is formed on the top surface, the position of the hole 13 does not shift even when the coil 20 is wound. Therefore, the shaft 90 is not easily shaken, and the holder 60 can be stably moved in the optical axis direction.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made to the embodiment of the present invention other than the above.

  For example, in the above embodiment, the magnet 70 is placed on the magnet mounting portion 64 from above, but the magnet 70 may be fitted into the magnet mounting portion 64 from the side as shown in FIG. good. In this case, the magnet mounting portion 64 is configured by a rectangular recess having a contour substantially the same as the side surface of the magnet 70, and the notch 14 of the base 10 passes through the portion 64 b of the holder 60 positioned above the magnet 70. It is changed to a possible size.

  Thus, in the place where the magnet 70 is fitted from the side, as shown in FIG. 9B, the magnet mounting portion 64 may be disposed slightly below the holder 60 (on the image sensor 201 side). In this case, the notch 14 of the base 10 is not formed up to the top surface of the base, and only the opening 12 through which the uppermost part of the holder 60 passes is formed on the top surface of the base 10.

  Further, the top surface of the holder 60 may be flush with each other as shown in FIG. In this case, an opening through which the entire top surface of the holder 60 can pass is formed in the upper part of the base 10. Alternatively, an opening smaller than the top surface of the holder 60 may be formed in the base 10, and a gap corresponding to the movement stroke of the holder 60 may be provided between the base 10 and the top surface of the holder 60. However, in this case, the lens driving device becomes larger in the lens optical axis direction by this gap.

  In the above embodiment, as shown in FIG. 3D, the magnet mounting portion 64 is arranged so that the magnet mounting portion 64 is entirely within the diameter range Wd of the lens 84 having the largest diameter. As shown in (d), the magnet mounting part 64 may be arranged so that a part of the magnet mounting part 64 protrudes from the range Wd. Further, as shown in FIG. 9D, the magnet mounting portion 64 may be arranged further inside than the above embodiment. In the case of FIG.9 (d), the magnet mounting part 64 is arrange | positioned in the position of the upper side (light incident side) rather than the said embodiment. For example, in the above embodiment, as shown in FIG. 3A, the magnet mounting portion 64 is formed so as to be placed on the lowermost step on the outer surface of the holder 60, but is placed on the upper step. As described above, the magnet mounting portion 64 may be formed.

  Moreover, in the said embodiment, although the one magnet 70 was distribute | arranged to one side of the holder 60, you may make it arrange | position two or more magnets on each side. Further, the magnet 70 may have an arc shape along the outer periphery of the holder 60. In this case, the magnet mounting portion 64 is also formed in an arc shape. The base 10 is also formed so that the coil 20 is wound in a circular shape.

  In the above embodiment, the two magnetic plates 30 and 30 are arranged on the base 10, but one or three or more magnetic plates may be arranged on the base 10. However, in this case as well, as in the above embodiment, it is desirable that the magnetic plate be arranged so that the magnetic force generated between the magnet and the magnetic plate is unbalanced in a plane perpendicular to the optical axis of the lens. .

  Further, the number of lenses accommodated in the holder 60 is not limited to four, and may be other numbers.

  Further, the shapes of the base 10 and the holder 60 are not limited to the above, and can be changed as appropriate. The diameters of the two shafts 90 may not be the same, and the holder 60 may be guided in the optical axis direction of the lens by a guide mechanism other than the shafts.

  In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 1 ... Lens drive device 10 ... Base 12 ... Opening (hole)
14 ... Notch (hole)
DESCRIPTION OF SYMBOLS 20 ... Coil 50 ... Base cover 60 ... Holder 70 ... Magnet 80 ... Lens group 90 ... Shaft

Claims (6)

Base and
A plurality of lenses with different diameters;
A holder for holding these lenses so that the plurality of lenses are aligned in the optical axis direction;
A magnet mounted on the holder;
A coil mounted on the base so as to face the magnet,
The magnet is disposed at a position corresponding to the lens having a small diameter inside the outer periphery of the lens having the largest diameter.
A lens driving device. The lens driving device according to claim 1,
The plurality of lenses are held by the holder so as to be arranged in order of decreasing diameter from the light incident side,
A lens driving device. The lens driving device according to claim 2,
The outer surface of the holder has a step shape according to the diameter of the lens,
A hole is formed in the base through which the structure composed of the magnet and the holder can pass when the holder moves in a direction approaching the base.
A lens driving device. The lens driving device according to claim 3,
The hole is disposed at a position corresponding to the uppermost part of the holder and the upper surface of the magnet.
A lens driving device. The lens driving device according to claim 4,
The base has a box shape having an opening at the bottom,
The holder on which the plurality of lenses and the magnet are mounted is housed in the base from the opening,
A base cover for fastening the holder in the base is attached to the base from the opening side.
A lens driving device. The lens driving device according to claim 5,
A hole is formed in the holder parallel to the optical axis direction,
In a state where the shaft is passed through the hole, both ends of the shaft are fixed to the receiving portion of the base and the receiving portion of the base cover, respectively.
A lens driving device.

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