JP4472433B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device used for a relatively small camera such as a camera of a camera-equipped mobile phone.

  As a lens driving device that drives a lens such as a camera lens in the optical axis direction, a cylindrical lens moving body that holds a moving lens on the inner peripheral side, and this lens moving body moves in the optical axis direction of the moving lens There is used a lens driving device that includes a driving means for driving and a fixed body that supports the lens moving body so as to be movable in the optical axis direction, and directly magnetically drives the moving lens.

This type of lens driving device includes a ring-shaped driving magnet disposed on the lens moving body and a driving coil disposed on the fixed body so as to face the outer peripheral side of the driving magnet. There is known a lens driving device that magnetically drives the lens moving body in the optical axis direction by controlling the energization of the lens (see, for example, Patent Documents 1 and 2).
JP 2000-187862 A JP-A-10-150759

  In recent years, inexpensive and lightweight resin lenses have been widely used as lenses used in cameras and the like in place of conventional glass lenses. In particular, there is a growing need for weight reduction in portable devices such as mobile phones, and resin lenses are used as lenses for cameras mounted on portable devices.

  Here, with a resin lens, it is difficult to form a lens having uniform optical characteristics over the entire area of the lens compared to a glass lens due to the influence of fluidity of the resin material at the time of molding. is there. Therefore, particularly when a resin lens is used, when the moving lens is moved in the optical axis direction by the lens driving device, the moving lens is shaken in the circumferential direction, and the moving lens held at each photographing position is moved. When the position in the circumferential direction varies, optical characteristics such as aberration of the moving lens vary depending on each photographing position. Furthermore, when the fixed body includes a fixed lens, the optical characteristics of the combination of the moving lens and the fixed lens greatly vary depending on each photographing position due to a synergistic effect with the optical characteristics of the fixed lens.

  However, the lens driving device described in the above-mentioned patent document does not include a configuration that suppresses the movement of the moving lens in the circumferential direction, and the optical characteristics of the moving lens vary depending on each shooting position that holds the moving lens. The problem that it ends up occurs.

  Accordingly, an object of the present invention is to provide a configuration that can suppress fluctuations in the moving lens in the circumferential direction around the optical axis, and can suppress fluctuations in the optical characteristics of the optical system of the lens driving device at each photographing position. It is in providing the lens drive device provided.

In order to solve the above problems, in the present invention, a cylindrical lens moving body that holds a moving lens on the inner peripheral side, a driving unit that moves the lens moving body in the optical axis direction of the moving lens, In a lens driving device including a fixed body that supports the lens moving body so as to be movable in the optical axis direction, the driving means includes a drive coil disposed on one of the lens moving body and the fixed body, A drive magnet disposed in a circumferential direction around the optical axis on the other of the lens moving body and the fixed body, and the lens driving device further includes the driving coil. set is provided with the lens movement, or magnetic pieces, wherein arranged to drive the magnet and opposed to the fixed body, the said lens movable body or the fixed body with a magnetic strip, the magnetic strip Magnetic piece holding portion extending in radial direction around the optical axis for holding is formed, the magnetic piece is arranged so as to face only the optical axis direction end face of the drive magnet and the driven magnet The lens moving body is held in the circumferential direction by a magnetic attraction force between the drive magnet and the magnetic piece, and the movable range end in the optical axis direction. In the position, the lens moving body is held in the optical axis direction .

In the present invention, a drive coil is disposed on one of the lens moving body and the fixed body, and a plurality of drive magnets are provided on the other of the lens moving body and the fixed body along the circumferential direction centering on the optical axis. And a magnetic piece is disposed on the lens moving body or fixed body on which the drive coil is disposed. Further, the magnetic piece is disposed so as to face only the end surface in the optical axis direction of the drive magnet , and is disposed so as to face the position where the magnetic flux of the drive magnet is concentrated, that is, the position where the magnetic flux density of the drive magnet is high. ing. Therefore, the magnetic piece is attracted to a position where the magnetic flux density of the drive magnet is high, and the lens moving body, that is, the moving lens is stabilized in the circumferential direction around the optical axis. Therefore, even if the lens moving body holding the moving lens moves in the circumferential direction, the magnetic piece is attracted to a position where the magnetic flux density of the driving magnet is high at the moving lens holding position, that is, the shooting position. Produces a circumferential restoring force. As a result, it is possible to suppress fluctuations in the circumferential position of the moving lens at each photographing position.
In addition, by setting the movable range end position of the lens moving body as the photographing position, that is, the lens holding position, it is not necessary to keep the drive coil energized at the holding position, and the power consumption in the lens holding state can be reduced. Can be reduced.

In the present invention, the drive magnet includes an inner surface formed on the inner side with the optical axis as a center and an outer surface formed on the outer side, and the inner surface and the outer surface are each magnetized with a single pole. The magnetic piece is preferably disposed so as to face only the end face in the optical axis direction of the drive magnet at a substantially central position in the circumferential direction around the optical axis of the drive magnet. By unipolarly magnetizing the inner side surface and the outer side surface, the magnetic flux concentrates at a substantially central position of the drive magnet in the circumferential direction around the optical axis. Therefore, with a simple configuration in which the drive magnet and the magnetic piece are opposed to each other at a substantially central position in the circumferential direction of the drive magnet, a restoring force is generated in the moving lens, and fluctuations in the circumferential position of the moving lens are suppressed. be able to.

  In the present invention, for example, the moving lens is a resin lens. In the case of a resin lens, in particular, it is difficult to form a lens having uniform optical characteristics over the entire area of the lens, and when the circumferential position of the moving lens varies, the optical system of the lens moving device Variations in the optical characteristics of the However, if the configuration of the present application is adopted, fluctuations in the circumferential position of the moving lens can be suppressed, so even if an inexpensive and lightweight resin lens is used as the moving lens, lens driving at each shooting position is possible. Variations in the optical characteristics of the optical system of the apparatus can be suppressed.

  In the present invention, for example, the fixed body is provided with a fixed lens having an optical axis substantially coaxial with the optical axis of the moving lens. When the fixed lens is arranged on the fixed body, if the position of the moving lens in the circumferential direction varies, the optical characteristics of the combination of the moving lens and the fixed lens will vary depending on the synergistic effect with the optical characteristics of the fixed lens. It varies greatly depending on the shooting position. However, if the configuration of the present application is adopted, fluctuations in the circumferential position of the moving lens can be suppressed, so fluctuations in the optical characteristics of the optical system of the lens driving device at each photographing position can be suppressed.

  In the present invention, for example, the fixed lens is a resin lens. When the fixed lens is made of resin, the optical characteristics of the combination of the moving lens and the fixed lens due to the positional fluctuation in the circumferential direction of the moving lens is particularly dependent on each shooting position. It will fluctuate greatly. However, if the configuration of the present application is adopted, fluctuations in the circumferential position of the moving lens can be suppressed, so fluctuations in the optical characteristics of the optical system of the lens driving device at each photographing position can be suppressed.

  In the present invention, the magnetic piece is preferably a chip-like magnetic piece. By using a chip-shaped magnetic piece, the entire lens driving device can be reduced in size. Moreover, the position where the magnetic flux density of the drive magnet is high and the magnetic piece can be reliably opposed.

  In the present invention, it is preferable that the drive magnets are disposed on either the lens moving body or the fixed body at equal angular intervals with the optical axis as the center. In this case, a uniform restoring force is generated in the circumferential direction. For this reason, it is possible to appropriately suppress the position variation in the circumferential direction of the moving lens.

In the present invention, the holding position of the magnetic piece, which is preferably adjustably configured in the radial direction about the optical axis. In this case, the magnetic attraction force generated between the drive magnet and the magnetic piece can be adjusted by adjusting the holding position of the magnetic piece. That is, the restoring force in the circumferential direction of the moving lens can be adjusted. Therefore, an appropriate restoring force in the circumferential direction of the moving lens can be set.

  In the present invention, for example, the driving means further includes a yoke disposed on the fixed body to form a magnetic circuit together with the driving coil and the driving magnet, and the driving coil is disposed on the lens moving body. The drive magnet is disposed on the fixed body. That is, the present invention can be applied to a lens driving device having such a configuration, for example, a lens driving device in which a voice coil motor is configured as a driving unit.

As described above, in the present invention, the magnetic piece is disposed so as to face only the end surface in the optical axis direction of the drive magnet in the optical axis direction, and is disposed so as to face the position where the magnetic flux density of the drive magnet is high in the circumferential direction. Has been. Therefore, the magnetic piece is attracted to a position where the magnetic flux density of the drive magnet is high, and is stabilized in the circumferential direction around the optical axis. Therefore, even if the lens moving body that holds the moving lens moves in the circumferential direction, the magnetic piece is attracted to a position where the magnetic flux density of the driving magnet is high at the holding position of the moving lens, that is, the photographing position. Occurs. As a result, the variation in the circumferential position of the moving lens can be suppressed at each photographing position, and the variation in the optical characteristics of the optical system of the lens driving device can be suppressed at each photographing position. In the holding position, it is not necessary to keep the drive coil in an energized state, and the power consumption in the lens holding state can be reduced.

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

[Embodiment 1]
(Configuration of lens driving device)
FIG. 1 is a side sectional view showing a lens driving device according to Embodiment 1 of the present invention. 2A and 2B show a fixed side member of the lens driving device shown in FIG. 1, in which FIG. 2A is a top view thereof, and FIG. 3A and 3B show a fixed body of the lens driving device shown in FIG. 1, FIG. 3A is a top view thereof, and FIG. 3B is a cross-sectional view taken along the line BB of FIG. 4A and 4B show a yoke of the lens driving device shown in FIG. 1, FIG. 4A is a top view thereof, and FIG. 4B is a cross-sectional view taken along a line CC in FIG. 5A and 5B show a moving side member of the lens driving device shown in FIG. 1, in which FIG. 5A is a top view thereof, FIG. 5B is a cross-sectional view taken along a line DD in FIG. is there. FIG. 6 is a perspective view schematically showing an arrangement relationship between the driving magnet and the magnetic piece of the lens driving device shown in FIG.

  A lens driving device 1 according to the present embodiment is applied to a thin camera mounted on a portable device such as a mobile phone, and includes a lens moving body 2 that holds moving lenses 13 and 14, and the lens moving body 2. Driving means 4 for moving the lens moving body 13 and 14 in the optical axis L direction, and a fixed body 3 that supports the lens moving body 2 so as to be movable in the optical axis L direction. In this embodiment, the drive means 4 is composed of a drive coil 5, a drive magnet 6, and a yoke 8 that forms a magnetic circuit together with the drive coil 5 and the drive magnet 6. A cover 10 holding a fixed lens 12 is fixed to the upper end of the fixed body 3 in the figure. Note that the fixed lens 12 and the movable lenses 13 and 14 in this embodiment are both resin lenses formed of a resin material.

  As shown in FIGS. 1 and 2, the fixed body 3 is provided with a drive magnet 6 and a yoke 8.

  The fixed body 3 in the present embodiment is a resin member formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion, and forms a main body case of the lens driving device 1 (see FIG. 3). At the bottom of the fixed body 3, an opening 3a for capturing an image of the object to be photographed is formed. Around the opening 3a, a yoke fixing portion 3b for fixing the yoke 8 is formed. Specifically, the yoke fixing portions 3b are formed at three locations with a 120 ° pitch centered on the optical axis L. Between the respective yoke fixing portions 3b, restriction recesses 3c for restricting the movable range of the lens moving body 2 in the optical axis L direction in the illustrated downward direction are formed at three positions with a 120 ° pitch centered on the optical axis L. Has been. As shown in FIG. 3A, the boundary line between the yoke fixing portion 3b and the regulating recess 3c is formed at a pitch of 60 ° with the optical axis L as the center.

  The yoke fixing portion 3b includes a fixing surface 3b1 and a fitting convex portion 3b2 formed to fix the yoke 8 at a substantially central position of the fixing surface 3b1. Since the fixing surface 3b1 fixes the yoke 8 with high accuracy, the flatness is ensured with high accuracy. Moreover, the regulation recessed part 3c is formed in the state depressed from the fixed surface 3b1. Of the restricting portions 3c formed at three places, a lead hole 3d for drawing a wiring board 11 described later to the outside of the fixed body 3 is formed at one place so as to penetrate from the restricting recess 3c to the outside of the fixed body 3. Has been.

  In addition, a protrusion 3e used for positioning the yoke 8 in the circumferential direction is formed on the outer peripheral side of each regulating recess 3c so as to protrude in the optical axis L direction. Specifically, the cross section in the direction of the optical axis L is formed in a substantially arc shape along the inner peripheral surface of the cylindrical portion of the fixed body 3.

  The yoke 8 is formed of a plate-like magnetic member, and includes an inner yoke 8a, an outer yoke 8b formed radially outside the inner yoke 8a, and a connecting portion that connects the inner yoke 8a and the outer yoke 8b. 8c. Specifically, the yoke 8 has a groove shape in which the connecting portion 8c connects the inner yoke 8a and the outer yoke 8b at the lower end in the figure, and the inner yoke 8a and the outer yoke 8b stand upright from the connecting portion 8c. (See FIG. 4). The illustrated lower surface of the connecting portion 8 c is a fixed reference surface 8 e for fixing the yoke 8 to the fixed body 3. In this embodiment, the yoke 8 is formed by bending a thin plate-like magnetic member with a press, and the perpendicularity of the inner yoke 8a and the outer yoke 8b with respect to the fixed reference surface 8e is ensured with high accuracy.

  As shown in FIG. 4A, the inner yoke 8a is formed in a substantially arc shape centered on the optical axis L when viewed from above. Similarly, the outer yoke 8b is formed in a substantially arc shape centered on the optical axis L when viewed from above, and the outer yoke 8b is disposed on the fixed body 3 and is a cylinder of the fixed body. It is arranged along the part. Further, a fitting hole 8d that fits with the fitting convex portion 3b2 formed in the fixed body 3 is formed at a substantially central position of the connecting portion 8c.

  In this embodiment, three yokes 8 are fixed to a yoke fixing portion 3 b formed on the fixed body 3. More specifically, the yoke 8 is fixed to the yoke fixing portion 3b in a state where the fixing reference surface 8e is in contact with the fixing surface 3b1 and the fitting hole 8d is fitted to the fitting convex portion 3b2. ing. At this time, the circumferential end of the outer yoke 8b is adjacent to the protrusion 3e. In a state where the yoke 8 is fixed to the fixed body 3, the inner yoke 8a and the outer yoke 8b extend in the optical axis L direction. In this embodiment, the inner yoke 8a is a guide protrusion for guiding the lens moving body 2 in the direction of the optical axis L, and the inner yoke 8a has a pitch of approximately 120 ° with the optical axis L as the center. It is erected on the fixed body 3 at equal intervals. On the surface of the inner yoke 8a, the maximum height of the surface roughness is about 0.1 μm or less in order to reduce sliding resistance with a sliding hole 2b of the lens moving body 2 described later.

  As shown in FIG. 2A, the drive magnet 6 is a thin plate-like permanent magnet having a substantially arc-shaped cross section in the optical axis L direction and extending in the optical axis L direction. The inner peripheral surface 6a and the outer peripheral surface 6b are provided. The inner peripheral surface 6a and the outer peripheral surface 6b are each magnetized with a single pole. For example, the inner peripheral surface 6a of the drive magnet 6 is magnetized to the N pole, and the outer peripheral surface 6b is magnetized to the S pole. Therefore, the magnetic flux is concentrated at the approximate center position in the circumferential direction of the drive magnet 6 and the magnetic flux density is high. Further, the circumferential length of the drive magnet 6 is substantially equal to that of the outer yoke 8b.

  In this embodiment, three drive magnets 6 are arranged on the fixed body 3 along the circumferential direction centered on the optical axis L. Specifically, the drive magnet 6 is fixed to the inner peripheral side of the outer yoke 8b of the three yokes 8 fixed to the fixed body 3 by fixing means such as adhesion, and the drive magnet 6 is centered on the optical axis L. Are arranged on the fixed body 3 at equal angular intervals.

  As shown in FIG. 5, the lens moving body 2 is a resin member formed in a cylindrical shape having flanges 2 a and 2 a at the upper and lower ends in the drawing. In this embodiment, the lens moving body 2 holds the moving lenses 13 and 14 on the inner peripheral side, and the drive coil 5 is directly wound between the flanges 2a and 2a on the outer peripheral side. That is, in this embodiment, the lens moving body 2 also serves as a coil bobbin. In this embodiment, the lens moving body 2 directly holds the moving lenses 13 and 14 on the inner peripheral side thereof. However, the moving lens 13 and 14 may be held via the lens barrel. .

  The lens moving body 2 has a sliding hole 2b through which an inner yoke 8a serving as a guide protrusion is inserted and slidably contacted with the inner yoke 8a. And formed in three places. As shown in FIG. 5A, the sliding hole 2b is formed in a substantially arc shape when viewed from above, and is formed so as to penetrate the lens moving body 2 in the optical axis L direction. The radial width of the sliding hole 2b is larger than the radial thickness of the inner yoke 8a. However, the sliding hole 2b and the inner hole 8b in the state where the inner yoke 8a is inserted into the sliding hole 2b are formed. The radial gap with the yoke 8a is set to be 0.1 mm or less on one side. Thus, a sliding guide is formed by the inner yoke 8a and the sliding hole 2b, and the lens moving body 2 is appropriately guided in the optical axis L direction by the inner yoke 8a.

  In order to reduce the sliding resistance with the inner yoke 8a, a lubricating coating may be formed on the surface of the sliding hole 2b. Specifically, an electroless nickel plating film in which polytetrafluoroethylene (PTFE) is dispersed may be formed on the surface of the sliding hole 2b. In this case, it is necessary to form the lens moving body 2 with a heat resistant resin such as a liquid crystal resin or a polyphenylene sulfide resin (PPS).

  A magnetic piece holder 2 c for holding the chip-like magnetic piece 9 is formed on the upper flange 2 a of the lens moving body 2 in the figure. Specifically, it is formed at three locations at approximately 120 ° pitches at approximately the center position in the circumferential direction of the sliding hole 2b and outward from the outside in the radial direction of the sliding hole 2b. The holding position of the magnetic piece 9 can be adjusted in the radial direction. The magnetic piece 9 in this embodiment is a thin plate having a rectangular cross section in the optical axis L direction. The rectangular magnetic piece 9 generally has different magnetic anisotropy characteristics depending on its direction. In this embodiment, the magnetic piece 9 is held by the lens moving body 2 so that the direction of strong magnetic anisotropy faces the radial direction. ing. In other words, the magnetic anisotropy is arranged so that the direction of strong magnetic anisotropy faces the direction of the drive magnet 6.

  On the bottom surface of the lens moving body 2, there are regulating convex portions 2 d that abut the regulating concave portion 3 c of the fixed body 3 and regulate the movable range of the lens moving body 2 in the downward direction between the three sliding holes 2 b. Is formed. A wiring board 11 for supplying a drive current to the drive coil 5 is fixed to the bottom surface of the lens moving body 2. The wiring board 11 in this embodiment is a flexible printed circuit board (FPC), and the end of the drive coil 5 is connected to the wiring pattern on the wiring board 11.

  The lens moving body 2 in which the driving coil 5 is wound on the outer peripheral side and the magnetic piece 9 is held by the magnetic piece holding portion 2 c is disposed inside the cylindrical portion of the fixed body 3. Specifically, the inner yoke 8a is inserted into the sliding hole 2b, and the restricting convex portion 2d and the restricting concave portion 3c are arranged to face each other in the optical axis L direction. At this time, the drive coil 5 is disposed so as to be sandwiched in the radial direction by the drive magnet 6 and the inner yoke 8 a, and the drive coil 5, the drive magnet 6 and the yoke 8 serve as the drive means 4. A voice coil motor is configured.

  When the lens moving body 2 is disposed inside the cylindrical portion of the fixed body 3, each magnetic piece 9 faces the upper end surface of the drive magnet 6 in the direction of the optical axis L in the figure. . More specifically, in a state where the lens driving device 1 is viewed from the upper surface, each magnetic piece 9 is at a substantially central position in the circumferential direction around the optical axis L of the driving magnet 6. It arrange | positions so that an upper surface may be opposed (refer FIG. 6). In FIG. 6, the lens moving body 2 is omitted for convenience of explanation.

  Further, in a state where the lens moving body 2 is disposed inside the cylindrical portion of the fixed body 3, the wiring board 11 is drawn out of the fixed body 3 from the extraction hole 3 d formed in the fixed body 3. .

  The cover 10 is a resin member formed in a bottomed cylindrical shape, and is formed so that the outer diameter thereof substantially coincides with the fixed body 3. An opening is formed at the bottom of the cover 10, and the fixed lens 12 is held in this opening. Further, on the lower side of the cover 10 in the figure, a restricting portion (not shown) that restricts the movable range of the lens moving body 2 in the upward direction in the optical axis L direction is formed. The cover 10 is fixed to the fixed body 3 so that the optical axes of the fixed lens 12 and the moving lenses 13 and 14 coincide. That is, the fixed lens 12 having an optical axis substantially coaxial with the moving lenses 13 and 14 is disposed on the fixed body 3 via the cover 10.

(Operation of lens driving device)
The operation of the lens driving device 1 configured as described above will be described below.

  In this embodiment, as shown in FIG. 1, the normal moving lens holding position is a state in which the restriction convex portion 2 d of the lens moving body 2 is in contact with the restriction concave portion 3 c of the fixed body 3. In this state, the lens moving body 2 is stably held in the direction of the optical axis L by the magnetic attractive force between the magnetic piece 9 and the drive magnet 6. Therefore, the drive coil 5 is in a non-energized state at the normal moving lens holding position. Each magnetic piece 9 is opposed to a substantially central position in the circumferential direction centered on the optical axis L of the drive magnet 6. Therefore, the magnetic piece 9 is attracted to a substantially central position of the drive magnet 6 in the circumferential direction, that is, a position where the magnetic flux density is high, and the lens moving body 2 is stably held also in the circumferential direction.

  When a current is supplied to the drive coil 5 so that the lens moving body 2 moves in the upward direction in the figure while the lens moving body 2 is held at the normal moving lens holding position, the lens moving body 2 8A and the sliding hole 2b are guided in the direction of the optical axis L, and a focusing operation is performed in which the lens moving body 2 moves until the upper end of the lens moving body 2 comes into contact with the restricting portion formed on the cover 10. The lens moving body 2 that has moved from the normal moving lens holding position to a predetermined position in the optical axis L direction by this focusing operation is balanced with the magnetic attraction force between the magnetic piece 9 and the drive magnet 6. Is kept stable at a predetermined position. Since each magnetic piece 9 is arranged at the center position in the circumferential direction of the drive magnet 6 in the same manner as the normal moving lens holding position, the lens moving body 2 is arranged in the circumferential direction. The magnetic piece 9 and the drive magnet 6 are stably held.

  When a current is supplied to the drive coil 5 so that the lens moving body 2 moves downward in the figure at the predetermined position, the lens moving body 2 is moved in the direction of the optical axis L by the inner yoke 8a and the sliding hole 2b. Move as guided by. For example, the lens 2 is moved until the restriction convex portion 2d of the lens moving body 2 comes into contact with the restriction concave portion 3c of the fixed body 3, and is held at a normal moving lens holding position. Depending on the magnitude of the magnetic attractive force generated between the magnetic piece 9 and the drive magnet 6, the lens moving body 2 can be moved in a normal state by turning off the drive coil 5 at the predetermined position. It is also possible to move to the moving lens holding position.

(Main effects of this form)
As described above, in the lens driving device 1 of the present embodiment, the three driving magnets 6 are disposed on the fixed body 3 along the circumferential direction around the optical axis L, and the driving coil is mounted on the lens moving body 2. 5 and a magnetic piece 9 are disposed. Further, the magnetic piece 9 is disposed so as to face a substantially central position in the circumferential direction around the optical axis L of the drive magnet 6, that is, a position where the magnetic flux of the drive magnet 6 is concentrated. Therefore, the magnetic piece 9 is attracted to a position where the magnetic flux density of the drive magnet 6 is high, and the lens moving body 2, that is, the moving lenses 13 and 14 are stabilized in the circumferential direction around the optical axis L. Therefore, even if the lens moving body 2 holding the moving lenses 13 and 14 moves while moving in the circumferential direction around the optical axis L, the magnetic piece at the holding position of the moving lenses 13 and 14, that is, the photographing position, 9 is attracted to a position where the magnetic flux density of the drive magnet 6 is high, and a restoring force in the circumferential direction is generated in the moving lenses 13 and 14. As a result, even if the lens moving body 2 moves in the circumferential direction or the lens driving device 1 vibrates at each photographing position, the circumferential direction around the optical axis L of the moving lenses 13 and 14 is used. Position fluctuation can be suppressed.

  In particular, in this embodiment, the inner peripheral surface 6a and the outer peripheral surface 6b of the drive magnet 6 are each magnetized with a single pole. The magnetic piece 9 is disposed so as to face the substantially central position of the drive magnet 6 in the circumferential direction centered on the optical axis L, that is, the position where the magnetic flux of the drive magnet 6 is concentrated. Therefore, with a simple configuration in which the drive magnet 6 and the magnetic piece 9 are opposed to each other at a substantially central position in the circumferential direction of the drive magnet 6, a restoring force in the circumferential direction is generated in the movable lenses 13 and 14, thereby moving the movable lens. The fluctuation | variation of the circumferential direction position of 13 and 14 can be suppressed.

  In this embodiment, a fixed lens 12 is disposed on the fixed body 3. When the fixed lens 12 is disposed on the fixed body 3, if the position of the movable lenses 13 and 14 in the circumferential direction varies, the fixed lens 12 and the movable lenses 13 and 14 are fixed by a synergistic effect with the optical characteristics of the fixed lens 12. The optical characteristics of the combination with the lens 12 vary greatly depending on each photographing position. However, if the configuration of the present embodiment described above is employed, fluctuations in the circumferential position of the moving lens 12 can be suppressed, and therefore fluctuations in the optical characteristics of the optical system of the lens driving device 1 at each photographing position are suppressed. be able to.

  In this embodiment, the moving lenses 13 and 14 and the fixed lens 12 are resin lenses. In the case of a resin lens, it is difficult to form a lens having uniform optical characteristics over the entire area of the lens due to the flow characteristics of the resin material at the time of molding. When the circumferential position varies, the variation in the optical characteristics of the optical system of the lens moving device 1 increases. However, if the configuration of the present embodiment described above is employed, fluctuations in the circumferential position of the movable lenses 13 and 14 can be suppressed. Therefore, even if an inexpensive and lightweight resin lens is employed, each photographing position The fluctuation of the optical characteristics of the optical system of the lens driving device 1 can be suppressed.

  In this embodiment, the magnetic piece 9 is formed in a chip shape. Therefore, even if the magnetic piece 9 is disposed on the lens moving body 2, the entire lens driving device 1 does not increase in size. Further, since the chip-like magnetic piece 9 is lightweight, the driving force of the lens moving body 2 is hardly affected. Further, by making the magnetic piece 9 into a chip shape, the magnetic piece 9 is surely positioned at the substantially central position in the circumferential direction around the optical axis L of the drive magnet 6, that is, the position where the magnetic flux of the drive magnet 6 is concentrated. Can be opposed to each other.

  In this embodiment, the drive magnet 6 and the magnetic piece 9 are disposed on the fixed body 3 and the lens moving body 2 at equal angular intervals around the optical axis L, respectively. Therefore, a uniform restoring force is generated in the circumferential direction, and position fluctuations in the circumferential direction of the movable lenses 13 and 14 can be appropriately suppressed.

  In this embodiment, the lens moving body 2 includes a magnetic piece 9 and is held by a normal moving lens that is the end position of the movable range of the lens moving body 2 in the downward direction by the magnetic attractive force of the magnetic piece 9 and the drive magnet 6. At the position, the lens moving body 2 is stably held in the optical axis L direction. Therefore, it is not necessary to keep the drive coil 5 energized at the normal moving lens holding position, and it is only necessary to energize the drive coil 5 only during the focusing operation. Therefore, the power consumption in the holding state of the movable lenses 13 and 14 can be reduced.

  In this embodiment, the magnetic piece holding portion 2c for holding the magnetic piece 9 of the flange portion 2a of the lens moving body 2 is formed outward in the radial direction, and the holding position of the magnetic piece 9 is set in the radial direction. Can be adjusted. Therefore, the magnetic attractive force generated between the drive magnet 6 and the magnetic piece 9 can be adjusted by adjusting the holding position of the magnetic piece 9. That is, the restoring force in the circumferential direction of the moving lenses 13 and 14 can be adjusted. Therefore, an appropriate restoring force in the circumferential direction of the moving lenses 13 and 14 can be set. Also in the optical axis L direction, an appropriate magnetic attractive force can be set between the drive magnet 6 and the magnetic piece 9.

(Modification of Embodiment 1)
In the embodiment described above, the fixed body 3 is integrally formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion, but the cylindrical portion and the bottom portion of the fixed body may be configured separately. For example, the cylindrical member 31 shown in FIG. 7 and the bottom member 32 shown in FIG. 8 may be formed separately and combined to form a fixed body. In FIG. 8, the opening 32a, the yoke fixing part 32b, the fixing surface 32b1, the fitting convex part 32b2, the restricting concave part 32c, the lead-out hole 32d, and the protrusion 32e are the opening part 3a and the yoke fixing part 3b in FIG. This corresponds to the fixing surface 3b1, the fitting convex portion 3b2, the regulating concave portion 3c, the extraction hole 3d, and the protrusion 3e.

  In the embodiment described above, the fixed body 3 is formed from a resin member. However, a part or all of the fixed body 3 may be formed from a metal member. In this case, leakage of magnetic flux to the outside of the fixed body 3 can be reduced, and the driving efficiency of the driving means 4 can be increased.

  Further, in the embodiment described above, the three yokes 8 are fixed to the fixed body 3, but the yokes may be integrally formed in a ring shape like a yoke 38 shown in FIG. When the yoke is integrally formed like the yoke 38, the handling of the parts becomes easy and the assembling work becomes easy. In FIG. 9, the inner yoke 38a, the outer yoke 38b, the connecting portion 38c, the fitting hole 38d, and the fixed reference surface 38e are respectively the inner yoke 8a, the outer yoke 8b, the connecting portion 8c, and the fitting hole 8d in FIG. Corresponds to the fixed reference plane 8e.

  Furthermore, in the three yokes 8, as shown in FIG. 10, a thin plate-like cover 48 made of a magnetic member may be fixed to the upper ends of the inner yoke 8a and the outer yoke 8b in the figure by bonding or the like. In this case, an effective magnetic path is formed by the yoke 8 and the cover 48, and the driving efficiency of the driving means 4 can be increased.

  In the above-described embodiment, the driving coil 5 is disposed on the lens moving body 2 and the driving magnet 6 is disposed on the fixed body 3. However, the driving magnet 6 is disposed on the lens moving body 2 and the stationary body. 3 may be provided with a drive coil 5.

  Further, in the embodiment described above, the three drive magnets 6 are disposed on the fixed body 3, but the two fixed drive bodies 6 may be disposed on the fixed body 3, or four or more drive magnets may be disposed. 6 may be provided. In this case, the magnetic piece 9 may be disposed so as to face the substantially central position in the circumferential direction around the optical axis L of all the drive magnets 6, or a part of the drive magnets 6. The magnetic piece 9 may be disposed so as to face the substantially central position in the circumferential direction.

  Furthermore, the magnetic piece 9 is not limited to a chip shape, and may be formed in a block shape as long as the driving of the lens moving body 2 is not affected. In that case, it is preferable that the shape of the magnetic piece 9 is such that the cross section in the optical axis L direction has a substantially arc shape. By doing so, it is possible to generate an appropriate restoring force in the circumferential direction with the drive magnet 6. Further, as the drive magnet, a flat rectangular parallelepiped drive magnet may be used.

[ Reference example ]
FIG. 11 is a side sectional view showing a lens driving apparatus according to a reference example of the present invention.

The lens driving device 51 according to the reference example is also applied to a thin camera mounted on a portable device such as a mobile phone, and moves a lens moving body 52 that holds a moving lens 63 and the lens moving body 52. A driving unit 54 that moves the lens 63 in the optical axis L direction and a fixed body 53 that supports the lens moving body 52 so as to be movable in the optical axis L direction are provided. In the reference example , the driving unit 54 includes a pair of driving coils 55a and 55b, a driving magnet 56, and a pair of yokes 57a and 57b that form a magnetic circuit together with the driving coils 55a and 55b and the driving magnet 56. ing. A cover 60 holding a fixed lens 62 is fixed to the upper end of the fixed body 53 in the figure. Further, a fixed lens 64 is fixed to the fixed body 53, and two fixed lenses 62 and 64 are disposed on the fixed body 3. The fixed lenses 62 and 64 and the moving lens 63 in the reference example are all resin lenses formed of a resin material.

  The fixed body 53 is a resin member formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion, and an opening portion 53a for capturing an image of a subject to be photographed is formed in the bottom portion. The fixed lens 64 is fixed so as to close the opening 53a. Further, as shown in FIG. 11, a pair of drive coils 55 a and 55 b wound in a ring shape is disposed on the cylindrical portion of the fixed body 53. More specifically, a ring-shaped flat yoke 57a is fixed to the upper surface of the drive coil 55a in the figure, and a ring-shaped flat yoke 57b is fixed to the lower surface of the drive coil 55b in the figure, and the drive coil 55a. And the drive coil 55b are disposed on the cylindrical portion of the fixed body 53 in a state of being separated so as to overlap in the optical axis L direction. A magnetic piece 59 described later is disposed between the pair of drive coils 55a and 55b in the optical axis L direction of the fixed body 3.

  The lens moving body 52 is a resin member formed in a bottomed cylindrical shape having a bottom portion and a cylindrical portion, and an opening portion 52a for capturing an image of the object to be photographed is formed on the bottom portion, and the opening portion 52a. The moving lens 63 is fixed so as to close the screen. A plurality of divided drive magnets 56 are fixed to the outer peripheral surface of the lens moving body 52 at equal angular intervals.

  The drive magnet 56 has a shape obtained by dividing a flat ring-shaped permanent magnet in the circumferential direction, and includes an inner peripheral surface 56a and an outer peripheral surface 56b with the optical axis L as the center. The inner peripheral surface 56a and the outer peripheral surface 56b are each magnetized with a single pole. For example, the inner peripheral surface 56a of the drive magnet 56 is magnetized to the N pole, and the outer peripheral surface 56b is magnetized to the S pole. Therefore, the magnetic flux is concentrated at the substantially central position in the circumferential direction of the drive magnet 56, and the magnetic flux density is high.

  The lens moving body 2 is disposed inside the cylindrical portion of the fixed body 3, and in this state, a drive magnet 56 is disposed so as to be sandwiched between the pair of drive coils 55a and 55b in the direction of the optical axis L. ing. Further, in the cylindrical portion of the fixed body 3, the lens drive device 51 is viewed from above, and the drive magnet 56 is located at a substantially central position in the circumferential direction around the optical axis L of each of the plurality of drive magnets 56. A plurality of magnetic pieces 59 are fixed so as to face the outer peripheral surface.

  The cover 60 is a resin member formed in a bottomed cylindrical shape, and an opening is formed at the bottom. A fixed lens 62 is held in the opening. The cover 60 is fixed to the fixed body 53 so that the optical axes of the fixed lens 62, the moving lens 63, and the fixed lens 64 coincide.

  In the lens driving device 51 configured as described above, a driving current is supplied to at least one of the pair of driving coils 55a and 55b, and a magnetic attractive force generated between the driving coils 55a and 55b and the driving magnet 56 and / or Alternatively, the lens moving body 52 moves in the direction of the optical axis L by the magnetic repulsive force. And it will be in a photography state in the upper and lower movable range ends. In this photographing state, the lens moving body 52 is stably held with respect to the fixed body 53 by the magnetic attractive force between the drive magnet 56 and the yoke 57a or the yoke 57b.

As described above, in the lens driving device 51 in the reference example , the lens moving body 52 is provided with the plurality of driving magnets 56 along the circumferential direction around the optical axis L, and the fixed body 53 has the driving coils 55a, 55b and a magnetic piece 59 are disposed. In addition, the magnetic piece 59 is disposed so as to face a substantially central position in the circumferential direction around the optical axis L of the drive magnet 56, that is, a position where the magnetic flux of the drive magnet 56 is concentrated. Therefore, the magnetic piece 59 is attracted to a position where the magnetic flux density of the drive magnet 56 is high. Therefore, even if the lens moving body 52 holding the moving lens 63 moves, the magnetic piece 59 is attracted to a position where the magnetic flux density of the drive magnet 56 is high even if the vibration occurs in the circumferential direction around the optical axis L. A restoring force in the circumferential direction is generated in the moving body 52, that is, the moving lens 63. As a result, it is possible to suppress fluctuations in the circumferential position around the optical axis L of the moving lens 63 at the holding position of the moving lens 63, that is, at each photographing position.

It is side surface sectional drawing which shows the lens drive device concerning Embodiment 1 of this invention. The fixed side member of the lens drive device shown in FIG. 1 is shown, (A) is the top view, (B) is sectional drawing in the AA cross section of (A). 1A and 1B show a fixed body of the lens driving device shown in FIG. 1, in which FIG. 1A is a top view thereof, and FIG. The yoke of the lens drive device shown in FIG. 1 is shown, (A) is a top view thereof, and (B) is a sectional view taken along the line CC of (A). 1A and 1B show a moving side member of the lens driving device shown in FIG. 1, in which FIG. 1A is a top view thereof, FIG. 1B is a cross-sectional view taken along a line DD in FIG. It is a perspective view which shows typically the arrangement | positioning relationship between the drive magnet and magnetic piece of the lens drive device shown in FIG. It is a top view which shows the cylindrical member of the fixed body in the modification of Embodiment 1 of this invention. The bottom member of the fixed body in the modification of Embodiment 1 of this invention is shown, (A) is the top view, (B) is sectional drawing in the EE cross section of (A). It is a top view which shows the yoke in the modification of Embodiment 1 of this invention. The yoke in the modification of Embodiment 1 of this invention is shown, (A) is the top view, (B) is sectional drawing in the FF cross section of (A). It is side surface sectional drawing which shows the lens drive device concerning the reference example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Lens moving body 2c Magnetic piece holding | maintenance part 3 Fixed body 4 Drive means 5 Drive coil 6 Drive magnet 6a Inner peripheral surface (inner surface)
6b Outer peripheral surface (outer surface)
8 Yoke 9 Magnetic piece 12 Fixed lens 13, 14 Moving lens 51 Lens driving device 52 Lens moving body 53 Fixed body 54 Driving means 55a, 55b Driving coil 56 Driving magnet 56a Inner peripheral surface (inner surface)
56b Outer peripheral surface (outer surface)
59 Magnetic piece 62, 64 Fixed lens 63 Moving lens L Optical axis

Claims (9)

A cylindrical lens moving body that holds a moving lens on the inner peripheral side, driving means that moves the lens moving body in the optical axis direction of the moving lens, and the lens moving body that is movably supported in the optical axis direction In a lens driving device provided with a fixed body,
The driving means includes a drive coil disposed on one of the lens moving body and the fixed body, and a circumferential direction around the optical axis on the other of the lens moving body and the fixed body. And a plurality of drive magnets arranged,
The lens driving device further includes a magnetic piece disposed on the lens moving body or the fixed body on which the driving coil is disposed so as to face the driving magnet.
In the lens moving body or the fixed body provided with the magnetic piece, a magnetic piece holding portion extending in a radial direction around the optical axis is formed to hold the magnetic piece,
The magnetic piece is arranged so as to face only the optical axis direction end face of the driving magnet, and is disposed so as to face the position where the magnetic flux of the drive magnet is concentrated, and the driving magnet and the magnetic pieces A lens driving device that holds the lens moving body in the circumferential direction by the magnetic attraction force and holds the lens moving body in the optical axis direction at a movable range end position in the optical axis direction . The drive magnet has an inner surface formed on the inner side with the optical axis as the center and an outer surface formed on the outer side, and the inner surface and the outer surface are each magnetized with a single pole,
The magnetic piece is disposed so as to face only an end surface in the optical axis direction of the drive magnet at a substantially central position in a circumferential direction around the optical axis of the drive magnet. Item 2. The lens driving device according to Item 1. The lens driving device according to claim 1, wherein the moving lens is a resin lens. The lens driving device according to claim 1, wherein a fixed lens having an optical axis substantially coaxial with the optical axis of the moving lens is disposed on the fixed body. The lens driving device according to claim 4, wherein the fixed lens is a resin lens. 6. The lens driving device according to claim 1, wherein the magnetic piece is a chip-like magnetic piece. 6. The lens according to claim 1, wherein the drive magnets are disposed on either one of the lens moving body and the fixed body at equal angular intervals with an optical axis as a center. Drive device. The lens driving device according to claim 1, wherein the holding position of the magnetic piece is configured to be adjustable in a radial direction about the optical axis. The drive means further comprises a yoke disposed on the fixed body to form a magnetic circuit together with the drive coil and the drive magnet,
6. The lens driving device according to claim 1, wherein the driving coil is disposed on the lens moving body, and the driving magnet is disposed on the fixed body.

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