JP2006171346A - Lens drive device and imaging apparatus equipped with device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive device in which miniaturization is achieved by decreasing the radius of an outer shape dimension, and to provide an imaging apparatus equipped with the device. <P>SOLUTION: The imaging apparatus 100 includes: a lens 7, a cylindrical lens barrel 6, at least the part of which is formed from a magnetic material, and an actuator 10 in which the lens barrel 6 is fitted. The actuator 10 has a rotary magnet 1, a coil 2, a stator 4 made from a soft magnetic material and a cam ring 5 made from a soft magnetic material. The coil 2, stator 4 and cam ring 5 compose a magnetic circuit for rotating the magnet 1. The lens barrel 6 and actuator 10 compose a lens drive device for magnetically driving the lens barrel 6 in the direction of an optical axis. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens driving device and an imaging device including the device, and in particular, a lens driving device that magnetically drives a lens support holding a lens in the direction of the optical axis of the lens, and an imaging device including the device. About.

  In recent years, an imaging apparatus such as a digital camera includes a lens barrel as a lens holder having a cylindrical shape, and the lens barrel is provided with a drive mechanism such as a zoom drive mechanism or an autofocus mechanism. In the lens barrel and the driving mechanism, it is required to shorten the lens barrel in the optical axis direction, that is, to reduce the thickness or reduce the size.

  As a lens driving device of a conventional imaging device, a small step motor having a solid cylindrical shape arranged in parallel with a lens in a lens barrel of the imaging device drives a lens via a lead screw portion or the like. No. 1 lens driving device has been proposed (see, for example, Patent Document 1). This step motor can be used to drive the diaphragm blades, shutters, lenses, and the like of the imaging apparatus.

  In addition, a second lens driving device has been proposed in which a linear step motor having a donut shape is used to drive a photographic lens disposed in the hollow portion (see, for example, Patent Document 2). This linear step motor includes a stator (stator) made of a soft magnetic material, a stator (magnet) made of a hollow soft magnetic material, and a plurality of coil windings wound around the magnet. The plurality of coil windings are arranged so that their central axes are directed toward the center of the optical axis of the holding frame (lens barrel) that holds the photographing lens, that is, in the direction perpendicular to the optical axis.

  Furthermore, a third lens driving device is proposed in which the lens barrel is configured to be movable only at two positions (see, for example, Patent Document 3). The third lens driving device can also be configured to be able to move the lens barrel to, for example, three positions (see, for example, Patent Document 4).

  FIG. 7 is a cross-sectional view schematically showing a part of the configuration of an imaging apparatus including a conventional third lens driving device, and FIG. 8 is an exploded perspective view showing the configuration of the lens driving device in FIG. 7 in detail. It is.

  As shown in FIG. 7, the conventional third lens driving device 300 has a rotatable cylindrical shape composed of magnetized portions 301a whose outer peripheral surfaces are divided in the circumferential direction and alternately magnetized with different magnetic poles. Magnet 301, coil 302 disposed in the optical axis direction with respect to magnet 301, hollow cylindrical stator 304 made of a soft magnetic material excited by coil 302, and the hollow portion of stator 304 as an optical path A lens holder (lens barrel) 307 for holding the lens 308 to be operated, and a female helicoid 306 disposed outside the lens barrel 307.

  The stator 304 includes at least one outer magnetic pole portion 304a formed in a tooth shape, and at least one substantially hollow cylindrical inner magnetic pole portion 304b formed in a tooth shape. The outer magnetic pole portion 304a and the inner magnetic pole portion 304b face each other via the magnetized portion 301a of the magnet 301, and these function as a yoke that suppresses leakage of magnetic flux between the magnet 301 and the coil 302 to the outside. .

  The female helicoid 306 is engaged with a male helicoid portion provided on the lens barrel 307, and these serve as lens feeding means for feeding the lens barrel 307 toward the optical axis as the magnet 301 rotates. Function. Note that the female helicoid 306 and the male helicoid portion (hereinafter simply referred to as “helicoid”) may be arranged on the outside of the lens barrel 307 in the optical axis direction, that is, on the magnet 301 side.

  The radius of the outer dimension of the lens driving device 300 is 3 of a space that defines the depth of the lens 308, the lens barrel 307, and the male helicoid portion constituting the movable element of the lens driving device with respect to the optical axis. Layers, and in addition to this, the inner magnetic pole portion 304b of the stator 304 that functions as a yoke constituting the stator of the lens driving device, that is, the inner yoke, the space between the magnet 301 and the inner yoke, the magnet 301, the magnet 301, The outer magnetic pole portion 304a, that is, the space between the outer yoke and the outer yoke, and a total of eight layers, between the stator and the movable element of the lens driving device 300, that is, between the inner yoke and the lens barrel 307. In addition, the lens barrel 307 is defined by one layer of space necessary for moving in the optical axis direction.

As described above, in the lens driving device 300, since the coil 302 and the magnet 301 are arranged in the optical axis direction, they do not occupy most of the range on the ground plane, and the first and second portions described above. It is more compact than the lens driving device.
Japanese Patent Laid-Open No. 11-190815 Japanese Utility Model Publication No. 56-172827 JP 2004-048873 A JP 2002-051524 A

  However, in the first lens driving device, since the step motor has a solid cylindrical shape and is arranged in parallel with the lens in the lens barrel, the diameter of the outer dimension of the lens barrel is equal to that of the lens barrel. The sum of the diameter and the diameter of the step motor increases the diameter of the lens barrel.

  In the second lens driving device, since the motor has a donut shape and a coil is wound around the outside of the magnet, the radius of the outer dimension of the lens driving device is the radius of the lens barrel and the coil. It is defined by the thickness dimension of the magnet and the stator, and the radius of the lens barrel cannot be reduced. In addition, since the center axis of the coil is perpendicular to the optical axis of the lens barrel, the shape of the coil becomes complicated, its assembly becomes complicated, and the number of parts increases, so that the imaging device can be made compact (compact) In addition, the number of coils increases and the cost increases.

  The third lens driving device 300 can be made more compact than the first and second lens driving devices. However, since the third lens driving device 300 is composed of eight layers as described above, the radius in the outer dimensions is sufficiently small. Difficult to do. Further, when the helicoid is arranged in the optical axis direction of the lens barrel 307, the thickness in the outer dimension of the lens driving device 300, that is, the length in the optical axis direction is increased, and the shortening cannot be achieved. On the other hand, if the helicoid is arranged in the radial direction of the lens barrel 307 in order to shorten the axis, the radius in the outer dimensions cannot be made sufficiently small.

  That is, the first to third lens driving devices drive the lens barrel and the stator including the outer yoke, the magnet and the coil, and the inner yoke arranged in the following order from the outer side in the radial direction. And a mover made up of a part of lens feeding means such as a male helicoid part and a lens barrel. Specifically, it is necessary to install an outer yoke and an inner yoke that function as yokes for the magnet and the coil on the stator side of the lens driving device. As a result, it is impossible to reduce the size by reducing the radius of the outer dimensions of the lens driving device by the thickness of the outer yoke and the inner yoke.

  An object of the present invention is to provide a lens driving device that can reduce the size of the outer dimension by reducing the radius of the outer dimension by installing an inner yoke on the movable element side, and an imaging device including the device.

  In order to achieve the above object, a lens driving device according to claim 1 is a cylindrical lens support for holding a lens having a predetermined optical axis, and the lens support is fitted inside and the light is magnetically received. A lens driving device including an actuator that drives in an axial direction is characterized in that at least a part of the lens support is made of a magnetic material.

  An imaging device according to an eleventh aspect includes the lens driving device, a lens supported by the lens support, and imaging means for imaging light incident through the lens.

  According to the present invention, since at least a part of the lens support is made of a magnetic material, the lens support can function as an inner yoke, eliminating the need to install the inner yoke on the stator side. It is possible to reduce the size by reducing the radius in dimensions.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a part of an imaging apparatus including a lens driving device according to the first embodiment of the present invention, and FIG. 2 shows a detailed configuration of the imaging apparatus of FIG. It is a disassembled perspective view shown in FIG.

  1 and 2, an imaging apparatus 100 including a lens driving device according to the present embodiment includes a lens 7 having a predetermined optical axis on which light from a subject is incident, and a cylinder at least part of which is made of a magnetic material. A lens barrel 6 having a shape, an actuator 10 that internally fits the lens barrel 6 and magnetically drives the lens barrel 6 in the optical axis direction, a base plate 9 for fixing the actuator 10, and a lens 7 And a sensor 8 for electronically recording the light transmitted through. The sensor 8 is made of, for example, a CCD (charge coupled device) or a C-MOS (Complementary-Metal Oxide Semiconductor), and is fixed to the base plate 9 via a screw or an ultraviolet curable resin.

  The lens barrel 6 and the actuator 10 constitute a substantially cylindrical lens driving device, each of which has a substantially cylindrical hollow portion having an opening for receiving light from a subject. Functions as a lens holding body that holds the lens 7 fitted on the inner peripheral surface thereof. The lens barrel 6, the lens 7, the sensor 8, the ground plane 9, and the actuator 10 are arranged so that a common optical axis (hereinafter referred to as “z-axis”) is the central axis.

  The base plate 9 is provided with a substantially cylindrical hollow portion, and the inner diameter thereof is substantially equal to the outer diameter of the lens barrel 6, and has a circumferential shape provided on the subject side, that is, the front surface in the z-axis direction. The formed grooves 9b and the key grooves 9c provided at, for example, three places at equal intervals in the circumferential direction on the inner peripheral surface, that is, every 120 degrees are formed.

  The groove 9b is provided concentrically with the rotation shaft of the magnet 1 described later, and is configured such that the distance between the magnet 1 and the outer magnetic pole teeth 4a described later is constant. The key groove 9c is formed in a columnar shape extending in a direction parallel to the z-axis, and a macro end abutting surface 9c ′ on which the lens barrel 6 abuts at a macro position described later is provided on the front surface thereof. The back surface is provided with a standard end abutting surface 9c "on which the lens barrel 6 abuts at a standard position, which will be described later. The key groove 9c may be provided at one or more locations, but is provided at three locations. Thus, the lens barrel 6 can be reliably supported so as to be parallel to the sensor 8.

  Hereinafter, the configuration of the actuator 10 will be specifically described.

  The actuator 10 includes a magnet 1 made of a magnetizable plastic magnet and configured to be rotatable, a bobbin 3 made of an insulating material, a coil 2 wound around the bobbin 3, and a soft material that is one of magnetic materials. A stator 4 and a cam ring 5 made of magnetic material, for example, electromagnetic soft iron such as SUY standardized by JIS are provided. The coil 2, the stator 4, and the cam ring 5 constitute a magnetic circuit for rotationally driving the magnet 1. SUY is a soft magnetic material that exhibits generally good characteristics such as low magnetic resistance and is suitable for use as a yoke. The magnetic material may be a ferromagnetic material such as a magnet as long as it is not a nonmagnetic material such as brass or aluminum.

  The magnet 1 has a cylindrical shape, and as shown in FIG. 3 which is a cross-sectional view taken along the line III-III in FIGS. 1 and 2, a magnetized portion 1a divided into n parts, for example, 12 parts in the circumferential direction. , Which is composed of three columnar drive pins 1b provided so as to protrude toward the inner diameter direction on the inner peripheral surface, and functions as a rotor (rotor) rotating in the circumferential direction around the z axis To do. The number of magnetized portions 1a indicates the number n of magnetized poles of the magnet 1 described later. A pair of magnetized portions 1a adjacent to each other are magnetized so that the outer surfaces of the magnet 1 have different magnetic poles (radial direction magnetization), and the three drive pins 1b are included in the magnetized portion 1a. On the circumferential surface, they are arranged at equal intervals in the circumferential direction, that is, every 120 degrees.

The plastic constituting the magnet 1 is made of, for example, a mixture of magnetic powder containing a Nb—Fe—B rare earth element and a binder material made of a thermoplastic resin such as a polyamide resin. When a polyamide resin is used as the binder material, the bending strength is 800 kg / cm ² or more. Thereby, sufficient bending strength can be ensured.

  The magnet 1 is manufactured by integrally forming the magnetized portion 1a and the drive pin 1b by injection molding. By injection molding, the thickness of the magnetized portion 1a can be easily reduced, and a thin film made of resin can be formed on the surface of the magnet 1 to protect the surface of the magnet 1.

  According to the magnet 1, since the magnetized portion 1a is formed in a thin cylindrical shape, the distance between an outer yoke and an inner yoke, which will be described later, can be shortened. And the magnetic resistance between the inner yoke and the inner yoke can be reduced. Since this magnetic circuit has a small magnetic resistance, a large amount of magnetic flux can be generated even when the magnetomotive force generated by energizing the coil 2 is small, and the performance of the actuator 10 can be improved.

  The bobbin 3 includes a pincushion shape portion 3a for winding the coil 2, and a bearing portion 3b arranged concentrically with the pincushion shape portion 3a. The bearing portion 3b is provided with three notches for the drive pin 1b to pass therethrough. The outer diameter of the pincushion-shaped portion 3a is substantially equal to the inner diameter of an outer magnetic pole tooth 4a described later of the stator 4, and the outer diameter of the bearing portion 3b is substantially equal to the inner diameter of the magnetized portion 1a. The bearing portion 3b functions as a bearing that supports the magnet 1 in the z-axis direction and the circumferential direction so as to rotatably support the magnet 1.

  The coil 2 has a cylindrical shape whose outer diameter is substantially equal to the outer diameter of the magnet 1, is arranged concentrically with the magnet 1, that is, parallel to the direction parallel to the z axis, and converts electric power into magnetic force (electromagnetic conversion). means). The magnetic circuit rotates the magnet 1 by the magnetomotive force generated by energizing the coil 2, and moves the lens barrel 6 in the z-axis direction by the rotational force generated by the rotation (lens driving means).

  The stator 4 has a plurality of, for example, six outer magnetic pole teeth 4 a having a comb tooth shape whose tip extends in a direction parallel to the z-axis, and a magnetic pole connection in which a later-described cylindrical portion 5 a of the cam ring 5 slides. The bobbin 3 around which the coil 2 is wound is fixed to the inner peripheral surface of the outer magnetic pole tooth 4a of the stator 4 by bonding or the like. The stator 4 is excited by a magnetic force generated by energizing the coil 2. Further, the stator 4 has an inner diameter and an outer diameter that are substantially equal to the inner diameter and the outer diameter of the groove 9b, and is configured to be securely fitted into the groove 9b. Since the groove 9b is securely fitted, the outer magnetic pole teeth 4a of the stator 4 can be prevented from bending.

  The outer magnetic pole teeth 4 a are provided at equal intervals so as to have an angle that is an integral multiple of 720 / n degrees in the circumferential direction, and are disposed outside the coil 2. The number of outer magnetic pole teeth 4a is set to be less than half the number n of magnetic poles of the magnet 1, that is, twelve. Since the outer magnetic pole teeth 4a extend in a direction parallel to the z-axis, the radius of the outer dimensions of the lens driving device can be reduced.

  The magnetic pole connecting portion 4 b has a cylindrical shape having a sliding surface with a smooth surface, and this sliding surface has a dimension in the z-axis direction, that is, a length so as to always contact the cam ring 5. The length of the magnetic pole connecting portion 4b is larger than the average thickness of the outer magnetic pole teeth 4a of the stator 4 or the cam ring 5, whereby the outer magnetic pole teeth 4a and the cam ring 5 are connected to the outer magnetic pole portion 4a. A surface area sufficient to transmit the generated magnetic force to the cam ring 5 can be secured. That is, the outer magnetic pole portion 4a and the cam ring 5 are connected to each other via the cylindrical portion 5a, thereby functioning as a yoke for the magnet 1 and the coil 2, thereby reducing magnetic resistance in the magnetic circuit and transmitting magnetic flux by the actuator 10. Efficiency can be improved.

  In addition, since the magnetic pole connecting portion 4b constitutes a part of the magnetic circuit, there may be a problem of adsorption with the cam ring 5 or the like. In such a case, it is preferable to insert a thin sheet material, for example, a Teflon (registered trademark) sheet, between the magnetic pole connecting portion 4b and the cylindrical portion 5a of the cam ring 5 and having good sliding properties. The thickness of the sheet material is more preferably about several tens of microns.

  The cam ring 5 includes a hollow cylindrical cylindrical portion 5a disposed inside the coil 2, and three cam grooves 5b disposed at equal intervals in the circumferential direction, that is, every 120 degrees, and is subjected to a drawing process or the like. Manufactured by.

  In addition, the cam ring 5 is sufficient in the z-axis direction so that the outer peripheral surface of the cam ring 5 always faces the inner peripheral surface of the magnet 1 even when the cam ring 5 is integrated with the lens barrel 6 and advances and retracts by a predetermined amount. It has dimensions and is fixed to the lens barrel 6 at a predetermined phase.

  The cam groove 5b is configured so that the three drive pins 1b are engaged with each other, and has a cam-shaped slope that allows the lens barrel 6 to smoothly advance and retract in the z-axis direction according to the rotation amount of the magnet 1. And a part of the actuator 10 that converts the rotation direction of the magnet 1 into the z-axis direction.

  The cylindrical portion 5a is surface-finished so that the magnetic pole connecting portion 4b of the stator 4 slides smoothly, and is fitted to the magnetic pole connecting portion 4b so as to reduce backlash. As a result, the stator 4 and the cam ring 5, both of which are made of a soft magnetic material, are magnetically connected, and the cam ring 5 is excited by transmitting the magnetic force of the outer magnetic pole teeth 4 a of the stator 4 excited by energizing the coil 2. . As a result, the magnetic circuit can reduce the magnetic resistance.

  As shown in FIG. 1, the outer magnetic pole teeth 4 a and the cam ring 5 sandwich the magnetized portion 1 a so as to face each other with a predetermined distance from the outer peripheral surface and inner peripheral surface of the magnetized portion 1 a of the magnet 1. To do. Thereby, since the magnetic flux generated in the outer magnetic pole teeth 4a and the cam ring 5 by the coil 2 effectively acts on the magnet 1 across the magnetized portion 1a, the output of the actuator 10 can be increased.

  The lens barrel 6 has a stepped portion that fits with the cam ring 5 on the outer peripheral surface, and the lens barrel 6 and the cam ring 5 are assembled integrally through the stepped portion. On the outer peripheral surface, there are provided three anti-rotation keys 6a fitted to the key grooves 9c so as to be movable only in the z-axis direction with respect to the base plate 9. The number of rotation stop keys 6 a is the same as the number of key grooves 9 c of the main plate 9.

  The rotation stop key 6a has a column shape extending in the z-axis direction, and a macro side abutting portion 6a ′ capable of abutting on the macro end abutting surface 9c ′ is provided on the front surface thereof. Is provided with a standard end butting portion 6a "that can come into contact with the standard end butting surface 9c". Therefore, the lens barrel 6 is configured such that its rotation is suppressed by the rotation stop key 6a having the macro side abutting portion 6a ′ and the standard end abutting portion 6a ″. Is configured to advance and retreat only in the z-axis direction via the slope of the cam groove 5b of the cam ring 5 when the drive pin 1b of the magnet 1 is rotationally driven.

  According to the actuator 10 in FIG. 1, since the magnet 1 is made of a plastic magnet material formed by injection molding, the thickness of the cylindrical magnet 1 can be made very small. As a result, the distance between the outer magnetic pole teeth 4a (outer yoke) and the cam ring 5 (inner yoke) of the stator 4 can be very short, and the magnetic resistance of the magnetic circuit can be reduced. Accordingly, the magnetic circuit can generate a large amount of magnetic flux with a small current, and can achieve an increase in output of the actuator 10 and a reduction in power consumption, and a reduction in the size of the coil 2.

  In addition, the imaging apparatus 100 according to the present embodiment has a cam ring having a thickness equal to the depth of the lens 7, the lens barrel 6, and the cam groove 5 b constituting the mover driven by the actuator 10 in order from the z axis. 5 (inner yoke), one layer between the magnetized portion 1 a of the magnet 1 and the cam ring 5, the magnet 1 constituting the stator of the actuator 10, and the outer magnetic pole teeth 4 a of the magnet 1 and the stator 4. The inner diameter dimension of the lens driving device is defined by a total of seven layers including a space between the outer magnetic pole teeth 4a and the outer magnetic pole teeth 4a. On the other hand, in an imaging device that drives a conventional lens barrel from the outside, for example, the imaging device of FIGS. 7 and 8, in order from the z axis, a lens that constitutes a mover driven by an actuator, a lens barrel, And three layers of the space defining the depth of the cam groove or male helicoid part, the inner yoke constituting the actuator stator, the space between the magnet and the inner yoke, the magnet, the space between the magnet and the stator, and the stator The inner diameter dimension of the lens driving device is defined by a total of eight layers including the above five layers and one layer of a space required between the stator and the movable element of the lens driving device 300. That is, in the imaging apparatus 100, by providing the inner yoke on the movable element side, the installation of the inner yoke provided on the movable element and the space between the magnet and the inner yoke in the conventional imaging apparatus is omitted, instead. A space between the magnet 1 and the cam ring 5 is provided. Thereby, the radius in the outer dimension of the lens driving device can be made smaller and smaller than the conventional imaging device in which the actuator 10 is arranged on the outer peripheral surface of the lens barrel 6. In the imaging apparatus 100, the thickness of the coil 2 and the thickness of the bobbin 3 are smaller than the dimension obtained by adding a predetermined necessary space to the thickness of the magnet 1, so that the coil 2 and the bobbin 3 are lens driven. It does not define the inner diameter of the device.

  Further, according to the imaging apparatus 100, the cam ring 5, which functions as the inner yoke, the magnet 1, the coil 2, and the stator 4 which functions as the outer yoke are provided outside the lens barrel 6, so that a magnetic circuit is generated. The radius of the lens driving device can be reduced without reducing the transmission efficiency of the magnetic flux.

  Furthermore, according to the imaging apparatus 100, first, the magnet 1 is formed in a hollow cylindrical shape, and its outer peripheral surface is magnetized in the radial direction, and secondly, the coil in the z-axis direction of the magnet 1 2, third, the outer magnetic pole teeth 4 a of the stator 4 excited by energizing the coil 2 face the outer peripheral surface of the magnet 1, and fourth, the cam ring 5 is soft magnetic It is formed of a separate part of the material, and is later assembled integrally with the lens barrel 6. Fifth, the cam groove 5b of the cam ring 5 faces the inner peripheral surface of the magnet 1. Sixth, The stator 4 and the cam ring 5 are magnetically coupled by sliding on the surface of the magnetic pole connecting portion 4b. Seventh, the outer magnetic pole teeth 4a are constituted by comb teeth extending in the z-axis direction. Therefore, stator 4, magnet 1, coil 2, It is possible to reduce the radius of the actuator 10 consisting of finely cam ring 5, it is possible to improve the output of the actuator 10.

  Further, since the magnet 1 is sandwiched between the stator 4 and the cam ring 5 that are magnetically coupled, the magnetic flux generated by energizing the coil 2 in the magnetic circuit is the outer magnetic pole teeth that function as the outer yoke. It acts efficiently across the magnet 1 between the cam ring 5 functioning as 4a and the inner yoke, and as a result, it is possible to reduce the leakage of magnetic flux and shorten the interval between necessary parts. can do.

  Further, since the outer magnetic pole teeth 4a are formed in a tooth shape extending in a direction parallel to the z axis of the magnet 1 having a cylindrical shape, the outer magnetic pole teeth 4a have an uneven shape in the radial direction so as to protrude toward the z axis. It is possible to reduce the radius of the lens driving device by eliminating the need for configuration.

  Furthermore, since the cam ring 5 is made of a soft magnetic material and is configured separately from the lens barrel 6, the portion that holds the lens 7 and the portion that includes the cam groove 5b are integrally configured. Therefore, it is possible to eliminate the necessity of manufacturing a component having a simple shape, and to simplify the shape of the lens barrel 6. As a result, the molding cost and the cost of the mold used at the time of molding can be reduced.

  Further, since the cam ring 5 and the lens barrel 6 that are integrally assembled are movable in the z-axis direction, one part of the inner magnetic pole portion provided in the conventional lens driving device is omitted, and the radius of the lens driving device is omitted. Can be reduced.

  From the above, at least a part of the lens barrel 6, that is, the cam ring 5 is made of a soft magnetic material and the lens barrel 6 is configured to be movable in the z-axis direction. The installation of the inner yoke on the stator side of the actuator 10 as the source can be omitted, and the radius of the lens driving device can be reduced.

  Hereinafter, the operation of the imaging apparatus 100 will be described with reference to FIGS. 3 and 4.

  The imaging apparatus 100 has a two-position switching mechanism for switching the position of the lens 7 by driving the lens barrel 6 between two positions. By switching the position of the lens 7, for example, the focus position of the lens 7 can be changed. As for the position of the lens 7, the lens barrel 6 is moved to the subject side in the z-axis direction so that the lens 7 is focused at a short distance (FIG. 3), and the lens barrel 6 is moved to the sensor 8 side. By doing so, there is a standard position (FIG. 4) in which the lens 7 is focused from infinity to medium distance.

  In the imaging apparatus 100, when energization to the coil 2 is interrupted, as shown in FIG. 3, the lens 7 is held at the macro position, and the magnet 1 is at a position corresponding to the angle θ1 in FIG. Is retained.

  In the state shown in FIG. 3, when the coil 2 is positively energized, the stator 4 is excited and the outer magnetic pole teeth 4a become the S pole. Subsequently, the magnetic pole portion 1a of the S pole facing the outer magnetic pole teeth 4a of the S pole receives a repulsive force, and the magnetic pole portion 1a of the N pole adjacent to the magnetic pole portion 1b of the S pole receives an attractive force. The energizing torque is generated in the magnet 1, and the magnet 1 rotates counterclockwise in FIG. 3, that is, in the positive direction of the θ axis.

  Next, the drive pin 1b moves along the slope of the cam groove 5b while maintaining a state in contact with the slope of the cam groove 5b, and the lens barrel 6 moves toward the sensor 8 side, that is, as the magnet 1 rotates. Move in the negative direction on the z-axis. Thereafter, the lens barrel 6 advances straight until the abutting portion 6a ″ of the rotation stop key 6a abuts against the abutting surface 9c ″ of the key groove 9c facing in the negative direction on the z axis, and the abutting portion 6a. When “abuts against the abutting surface 9c”, the lens barrel 6 is restricted from moving in the rotational direction by the rotation stop key 6a, and the position of the lens 7 is switched to the standard position as shown in FIG.

  4 is a cross-sectional view of the lens barrel 6 showing a state when the lens 7 in FIG. 1 is in the standard position.

  4 shows a state in which the bobbin 3 is rotated by an angle (θ2−θ1) in the circumferential direction at a position corresponding to the macro position of the lens 7 in FIG. 3, and the bobbin 3 is at the standard position of the lens 7. The case in the corresponding position is shown.

  In the state shown in FIG. 4, that is, when the magnet 1 is held at a position corresponding to the angle θ2 in FIG. 4, when the coil 2 is reversely energized, the outer magnetic pole teeth 4a that were S poles become N poles. . Subsequently, the N-pole magnetic pole portion 1a facing the N-pole outer magnetic pole tooth 4a receives a repulsive force, and the S-pole magnetic pole portion 1a adjacent to the N-pole magnetic pole portion 1b receives an attractive force. The magnet 1 generates energizing torque, and the magnet 1 rotates clockwise in FIG. 4, that is, in the negative direction of the θ axis.

  Next, the drive pin 1b moves along the slope of the cam groove 5b, and the lens barrel 6 moves in the positive direction on the subject side, that is, the z-axis, as the magnet 1 rotates. Thereafter, when the lens barrel 6 moves straight in the positive direction on the z-axis and the abutting portion 6a ′ contacts the abutting surface 9c ″, the lens barrel 6 is moved in the rotational direction by the rotation stop key 6a. The position of the lens 7 is switched to the macro position as shown in FIG.

  As described with reference to FIGS. 3 and 4, the position of the lens 7 can be stably switched between the standard position and the macro position by switching the energization direction to the coil 2.

In the above embodiment, the magnet 1 is made of a plastic magnet manufactured by injection molding. However, it may be a compression magnet manufactured by compression. In the case of a compression magnet, it is preferable to perform rust prevention treatment such as painting. Plastic magnets are preferable to compression magnets, and the resin film formed on the surface can greatly reduce the occurrence of rust compared to compression magnets, so the adhesion of magnetic powder generated on compression magnets This can eliminate the possibility of rust prevention. Furthermore, by omitting the rust prevention treatment, the quality can be improved without the surface bulging that tends to occur during the rust prevention treatment. Since the bending strength of the magnet 1 is 800 kg / cm ² or more, the strength can be improved as compared with a compression magnet having a bending strength of about 500 kg / cm ² .

  FIG. 5 is a cross-sectional view schematically showing a configuration of a part of an imaging apparatus including a lens driving device according to the second embodiment of the present invention, and FIG. 6 is a part of the imaging apparatus of FIG. It is a disassembled perspective view which shows a structure in detail.

  The lens driving device according to the present embodiment is the same as the lens driving device according to the first embodiment because the lens barrel 6 and the cam ring 5 in the first embodiment are different in configuration. The same reference numerals are given to the components and elements, and the description thereof is omitted.

  As shown in FIGS. 5 and 6, an imaging apparatus 200 including a lens driving device includes a lens barrel 16 in which the lens barrel 6 and the cam ring 5 are integrally formed, and the lens 7 is fitted therein to support the lens. Functions as a body. The lens barrel 16 and the stator 4 constitute a magnetic circuit similar to the above. The lens barrel 16, the magnet 1, the coil 2, the bobbin 3, and the stator 4 constitute an actuator 10.

  The lens barrel 16 is at least partially made of a soft magnetic material, such as electromagnetic soft iron, and is manufactured in a substantially cylindrical shape by a metal injection mold manufacturing method including an annealing process using an annealing furnace. Since the lens barrel 16 is magnetically connected to the stator 4, the magnetic resistance of the magnetic circuit can be reduced.

  The lens barrel 16 includes a cylindrical portion 15a having a surface finish so that the magnetic pole connecting portion 4b of the stator 4 can be smoothly slid and fitted with little backlash. The cylindrical portion 15a has the above-described rotation. A rotation stop key 16a corresponding to the stop key 6a and three cam grooves 16b corresponding to the cam groove 5b are formed.

  The operation of the imaging device 200 is the same as the operation of the imaging device 100 in the first embodiment. The cam groove 16b engages with the drive pin 1b, and the rotation direction of the magnet 1 changes the moving direction of the lens barrel 16. The lens barrel 16 smoothly advances and retreats in the z-axis direction according to the amount of rotation of the magnet 1, and the advance / retreat is restricted by the rotation stop key 16a coming into contact with a predetermined surface of the key groove 9c. Is done.

  According to the imaging device 200 of FIGS. 5 and 6, the same effect as the imaging device 100 can be obtained.

  Further, since the cam groove 16b is integrally formed in the lens barrel 16, it is necessary to form the cam groove 5b in the cam ring 5 which is a separate component from the stator 4 as in the first embodiment. The manufacturing cost can be reduced.

  Furthermore, since the lens barrel 16 is manufactured by a metal injection mold manufacturing method, a complicated three-dimensional shape in which the cam ring 5 and the lens barrel 6 are integrally formed can be easily formed. As a result, the number of parts can be reduced. Thereby, the lens barrel 16 can be effectively applied to an optical system of an imaging module provided in the imaging apparatus, an optical system of a micro camera, or the like. For example, the lens barrel of an ultra-compact camera can not only reduce the metal material cost as it is smaller, but also, the smaller the lens barrel, the annealing furnace used in the annealing process of the metal injection mold manufacturing method. The size can be used effectively, and the manufacturing cost per part can be further reduced.

  In addition, the lens barrel 16 is formed of a soft magnetic material, which is a magnetic material, and the cam groove 16b and the like are integrally formed and opposed to the inner peripheral surface of the magnet 1, so that the radius of the lens driving device is increased. While being able to make it small, the output of a lens drive device can be improved.

  In the first and second embodiments, the focus position of the lens 7 is changed by the two-position switching mechanism. However, the focal length of the lens 7 may be changed. The switching mechanism switches between two positions, but is not limited to this, and may switch a plurality of positions.

  In the above embodiment, the outer magnetic pole teeth 4a of the stator 4 have a comb-teeth shape extending in a direction parallel to the z-axis. However, the cam ring 5 extends in a direction parallel to the z-axis. You may have a shape.

  The lens driving device according to the embodiment of the present invention can be applied to an imaging device that electronically images light from a subject.

It is sectional drawing which shows roughly the structure of a part of imaging device provided with the lens drive device which concerns on the 1st Embodiment of this invention. It is a disassembled perspective view which shows the structure of the imaging device of FIG. 1 in detail. It is sectional drawing which follows the line III-III in FIG. 1, and shows a state when a lens exists in a macro position. It is sectional drawing of the lens barrel which shows a state when the lens in FIG. 1 exists in a standard position. It is sectional drawing which shows roughly the structure of a part of imaging device provided with the lens drive device which concerns on the 2nd Embodiment of this invention. It is a disassembled perspective view which shows the structure of a part of imaging device of FIG. 5 in detail. It is sectional drawing which shows schematically a part of structure of an imaging device provided with the conventional 3rd lens drive device. It is a disassembled perspective view which shows the structure of the lens drive device of FIG. 7 in detail.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnet 2 Coil 4 Stator 4a Outer magnetic pole tooth 4b Magnetic pole connection part 5 Cam ring 5a, 15a Cylindrical part 5b, 16b Cam groove 6, 16 Lens barrel 10 Actuator 100, 200 Imaging device

Claims (10)

  A lens driving device comprising: a cylindrical lens support that holds a lens having a predetermined optical axis; and an actuator that internally fits the lens support and is driven magnetically in the direction of the optical axis. A lens driving device characterized in that at least a part of the body is made of a magnetic material.   The actuator includes a cylindrical electromagnetic conversion unit that converts electric power into a magnetic force, an outer magnetic pole portion that is provided on an outer peripheral surface of the electromagnetic conversion unit and is excited by the magnetic force of the electromagnetic conversion unit, and the excited outer magnetic pole A magnet having a cylindrical shape that is rotationally driven about the optical axis by the magnetic force of the portion, and a lens driving means that moves the lens support in the direction of the optical axis by the rotational force generated by the rotation of the magnet. The lens driving device according to claim 1, further comprising:   The lens driving device according to claim 2, wherein the magnet is disposed inside the outer magnetic pole portion and disposed outside the lens support.   4. The lens driving device according to claim 2, wherein the plurality of magnets are magnetized such that a pair of adjacent magnets have different magnetic poles.   5. The lens driving device according to claim 2, wherein the lens support is provided with an inner magnetic pole portion made of the magnetic material and disposed inside the electromagnetic conversion unit.   6. The lens driving device according to claim 5, wherein one of the outer magnetic pole part and the inner magnetic pole part includes magnetic pole teeth extending in a direction parallel to the optical axis.   The outer magnetic pole part and the inner magnetic pole part have a cylindrical part provided so as to be connected to each other, and the cylindrical part has a dimension in a direction parallel to the optical axis of the outer magnetic pole part and the inner magnetic pole part. 7. The lens driving device according to claim 5, wherein the lens driving device is larger than an average value of at least one of the thicknesses.   The lens driving device according to any one of claims 5 to 7, wherein the lens support and the inner magnetic pole portion are configured integrally or separately.   The said lens support body comprises a part of said lens drive means, and changes the direction of rotation of the said magnet into the direction of the said optical axis, The one of the Claims 2 thru | or 8 characterized by the above-mentioned. Lens drive device.   A lens driving device according to any one of claims 1 to 9, a lens supported by the lens support, and imaging means for imaging light incident through the lens. Imaging device.

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