JP2009118722A - Actuator, imaging device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent impact resistance, and reduce size and thickness of an imaging device. <P>SOLUTION: An actuator includes: an optical member 16 for imaging an object as an imaging target, a holder 15 for holding the optical member 16, a magnetic circuit for moving the optical member 16 to an optical axis direction, and a base 18 for supporting the magnetic circuit. The magnetic circuit includes a coil 14 and a magnet 12. Either of the coil 14 and the magnet 12 is attached to the holder 15, and the other is attached to the base 18. A spherical body 17 is arranged in a gap between the holder 15 and the base 18, and the spherical body 17 is rotatable when the holder 15 moves in the optical axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an actuator provided with a magnetic circuit composed of a magnet, a coil, and a magnetic body, an imaging device, and an electronic device.

  In recent years, a camera built in a portable electronic device has been improved in image quality, and the number of pixels of an image sensor has been increased. In such portable electronic devices, there is often a tendency to mount an autofocus function necessary for improving image quality on an imaging device (camera). In order to perform autofocus, it is generally necessary to move the internal optical system. Here, a magnetic circuit using a magnet and a coil is used as an actuator for driving the optical system. As a system for driving the optical system, a voice coil system for driving a coil or a magnet due to an electromagnetic induction phenomenon by a magnetic circuit is widely used.

  In a voice coil actuator, a method of forming a parallel leaf spring by attaching two leaf springs to a holder is generally used as a method of supporting a holder that holds an optical system. The parallel leaf spring is deformed by a thrust generated by an electromagnetic induction phenomenon when a current is applied to the coil, and the holder is displaced in the optical axis direction.

For example, Patent Document 1 discloses component arrangement in an auto-focus mechanism of an optical system using such a parallel leaf spring. Patent Document 1 proposes an autofocus actuator that supports an imaging lens movably in the optical axis direction.
JP 2006-50693 A (published February 16, 2006)

  However, when the actuator using the conventional parallel leaf spring disclosed in Patent Document 1 is reduced in projection area and thinned (the height in the optical axis direction is reduced), the following problems occur.

  That is, in the conventional actuator, the holder for holding the optical system is held by the parallel leaf spring. Therefore, when the actuator is downsized, the strength of the parallel leaf spring is lowered. Hereinafter, the reduction in the strength of the parallel leaf spring will be described in detail.

  First, a configuration of a voice coil actuator using a conventional parallel leaf spring will be described with reference to FIG. FIG. 12 is a cross-sectional view showing a main configuration of a conventional actuator.

  The actuator shown in FIG. 12 is used for autofocus of an imaging device mounted on a general portable electronic device. As shown in FIG. 12, the conventional actuator includes a pair of leaf springs 10, a cylindrical magnet 12, a cylindrical yoke 13, a coil 14, and a cylindrical holder 15 that holds an optical member 16. It has. A magnet 12 and a coil 14 are provided inside the cylindrical yoke 13. A holder 15 is fixed inside the coil 14. A pair of leaf springs 10 are provided on both sides of the holder 15 in the optical axis direction. The holder 15 is fixedly supported by the leaf spring 10 and can move in the optical axis direction when the leaf spring 10 is deformed. Here, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, so that the holder 15 moves in the arrow direction (optical axis direction) shown in FIG. 12. It has become.

  With the recent progress in downsizing and thinning of imaging devices for portable electronic devices, there has been a demand for downsizing and thinning of autofocus actuators themselves. In order to satisfy this requirement, the volume of the magnetic circuit portion in the actuator must be reduced. Therefore, when the actuator is reduced in size and thickness, there is a problem that the efficiency of the magnetic circuit is lowered. As a result, the thrust per current in the magnetic circuit is reduced. In order to cope with this decrease in thrust, in the voice coil actuator shown in FIG. 12, it is necessary to reduce the spring constant of the pair of leaf springs 10 that support the holder 15.

  Here, generally, as a method of reducing the spring constant of the leaf spring 10, (i) increasing the length of the spring portion, (ii) reducing the spring width, or (iii) the plate of the leaf spring 10 One method is to reduce the thickness.

  (i) The method of increasing the length of the spring portion has a problem that the projected area of the actuator becomes large. Therefore, it is difficult to adopt the above method (i) due to the limitation of the actuator size.

  Further, (ii) a technique of reducing the spring width or (iii) a technique of reducing the plate thickness of the leaf spring 10 leads to a decrease in strength of the leaf spring 10. As a result, when the method (ii) or (iii) is adopted, when the holder 15 vibrates in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped, the holder 15 is attached to the holder 15. There is a concern that the plate spring 10 is plastically deformed. Then, when the leaf spring 10 is plastically deformed, there is a possibility that an abnormal operation of the actuator may occur. Further, the tilt of the optical system with respect to the image sensor increases, and the captured image may be deteriorated.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an actuator, an imaging device, and an electronic device that are excellent in impact resistance and can realize downsizing and thinning of the imaging device. There is.

  In order to solve the above problems, an actuator according to the present invention is an optical member that forms an image of an object to be imaged, a holder that holds the optical member, and an optical member that moves the optical member in the optical axis direction. An actuator comprising a magnetic circuit and a support for supporting the magnetic circuit, wherein the magnetic circuit comprises a coil and a magnet, one of the coil and the magnet being attached to the holder, and the other being the support. A spherical body is disposed in the gap between the holder and the support body, and the spherical body is configured to rotate by movement of the holder in the optical axis direction. It is a feature.

  According to said structure, the spherical body is distribute | arranged to the clearance gap between the said holder and the said support body, and the said spherical body is rotated by the movement of the optical axis direction of the said holder. The actuator according to the present invention does not have a configuration in which the holder is fixedly supported by a pair of leaf springs and the movement of the holder in the optical axis direction is supported by the pair of leaf springs, unlike the conventional actuator. Therefore, the above-described configuration does not cause the problem of “decrease in strength of the pair of leaf springs that hold the holder fixedly” as in the conventional actuator.

  Therefore, according to the above configuration, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is possible to provide an actuator that is excellent in impact resistance and that can realize downsizing and thinning of the imaging device.

  In the actuator according to the present invention, an insertion groove through which the holder is inserted is formed in the support, and the spherical body is in contact with both the side surface of the holder and the inner wall surface of the insertion groove. It may be arranged.

  According to said structure, since the said spherical body is distribute | arranged so that both the side surface of the said holder and the inner wall face of the said insertion groove may be contacted, when a holder moves to an optical axis direction, The spherical body rotates by friction. And it becomes possible to support a holder with the frictional force by rotation of this spherical body with respect to the movement of an optical axis direction. On the other hand, the displacement in the direction perpendicular to the optical axis direction of the holder is restricted by the spherical body that is in contact with the side surface of the holder.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and no member that supports (regulates) displacement in directions other than the optical axis direction is provided. It was. On the other hand, according to said structure, the spherical body has controlled the displacement of directions other than the optical axis direction of a holder. Therefore, as compared with a conventional actuator, the holder does not vibrate in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped.

  In the actuator according to the present invention, it is preferable that a plurality of the spherical bodies are arranged, and the spherical bodies are in a positional relationship so as to be sandwiched between the holders when viewed from the optical axis direction.

  According to said structure, since the said spherical body is arranged in multiple numbers, the contact area of a spherical body and a holder side surface becomes large, and the frictional force which arises on a holder side surface becomes large. Moreover, since each spherical body is in a positional relationship so as to sandwich the holder when viewed from the optical axis direction, the contact surface between the spherical body and the side surface of the holder is on the optical axis (center axis) of the holder. However, the support is not biased in a direction perpendicular to the optical axis direction, and more accurate movement support in the optical axis direction is possible.

  In particular, the spherical bodies are preferably arranged on the same plane perpendicular to the optical axis direction. As a result, it is possible to more accurately support movement in the optical axis direction.

  In the actuator according to the present invention, a recess is formed on the side surface of the holder, and a space capable of accommodating the spherical body is formed by the inner wall surface of the recess and the support. It is preferable.

  According to said structure, since the space which can accommodate the said spherical body is formed by the inner wall surface of the said hollow part and the said support body, when a holder moves to an optical axis direction, a spherical body is a holder. The contact between the holder side surface and the spherical body becomes more reliable without leaving the side surface. In addition, the actuator can be miniaturized.

  In the actuator according to the present invention, the elastic member that contacts the object side surface of the holder moving in the optical axis direction and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. It is preferable to be provided.

  According to the above configuration, when the elastic member contacts the object-side surface of the holder that moves in the optical axis direction, an elastic force that is proportional to the amount of movement of the holder that moves in the optical axis direction is generated. In the above configuration, the position of the holder is held by the balance between the thrust generated in the holder by electromagnetic induction by the magnetic circuit and the elastic force generated in the elastic member. Therefore, the position of the holder and the current value applied to the coil have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the above configuration, it is not necessary to perform special position control (for example, providing a separate position sensor) different from the conventional one, and the conventionally used position control method can be diverted. Therefore, it is possible to reduce the cost and size of the imaging device.

  The elastic member is in contact with the object-side surface of the holder that moves in the optical axis direction, and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. Good. Since the holder is supported by the spherical body, it is not necessary to have a configuration in which the holder is fixedly supported by the leaf spring as in the conventional actuator.

  For example, it is preferable that the elastic member is slidably in contact with the holder that moves in the optical axis direction. Thereby, compared with the conventional structure by which the holder was fixedly supported by the leaf | plate spring, the plastic deformation of an elastic member by the vibration of the holder at the time of fall of the imaging device for portable electronic devices is reduced.

  In the actuator according to the present invention, a plurality of the spherical bodies are arranged, the spherical bodies are arranged on the same plane perpendicular to the optical axis direction, and the elastic member is arranged on the plane. On the other hand, it is preferable that they are spaced apart in the optical axis direction.

  According to said structure, in order to make the optical axis direction movement of the said holder by a magnetic circuit smooth, each spherical body is distribute | arranged on the same surface perpendicular | vertical with respect to the said optical axis direction, and only one The elastic member is disposed away from the plane in the optical axis direction.

  In the conventional actuator, since the holder is fixedly supported by a pair of leaf springs, that is, two leaf springs, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by the two leaf springs. Become. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction. On the other hand, according to said structure, since only one elastic member is arrange | positioned, the spring constant required for the optical axis direction movement support of a holder can be designed with the spring constant of one elastic member. For this reason, compared to the conventional configuration, according to the above configuration, the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased. The problem of “decrease in strength of the pair of leaf springs to be held” does not occur.

  In the actuator according to the present invention, the support includes a first support that supports one end of the magnetic circuit in the optical axis direction, and a second support that supports the other end, and the spherical body. Is preferably arranged in any one of the gap between the holder and the first support and the gap between the holder and the second support. Even in such a configuration, since the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased, it is called “reduced strength of a pair of leaf springs that hold and hold the holder” like a conventional actuator. The problem does not invite.

  In the actuator according to the present invention, it is preferable that the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support.

  According to the above configuration, the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support body, so that the magnetic flux leakage of the magnet generated outside the actuator is reduced. Can do. Moreover, since the efficiency of the magnetic circuit of the actuator can be improved, the thrust per current can be improved.

  As described above, examples of the configuration of the magnetic circuit including the magnetic material having ferromagnetism include the following configurations.

  That is, in the actuator according to the present invention, the magnetic circuit may be configured by a coil provided on the outer periphery of the holder, the magnet disposed around the coil, and the magnetic body. With this configuration, the magnetic flux leakage of the magnet generated outside the actuator can be reduced.

  In the actuator according to the present invention, the magnetic circuit may include a magnet provided on an outer periphery of the holder, the coil disposed around the magnet, and the magnetic body.

  In particular, in the above configuration, since the magnet is provided on the outer periphery of the holder and the coil is arranged around the magnet, it is not necessary to provide a power supply wire in the holder as the movable part, and the structure can be simplified. There is an effect that can be.

  In the actuator according to the present invention, the spherical body is preferably made of a nonmagnetic material.

  Thus, since the spherical body is made of a nonmagnetic material, the spherical body does not affect the magnetic flux distribution by the magnetic circuit inside the actuator. Moreover, according to said structure, a spherical body does not adsorb | suck to a magnet in the case of an actuator assembly, and can improve an assembly workability | operativity.

  In the actuator according to the present invention, the two support bodies are provided with the magnet and the coil sandwiched in the optical axis direction, and the movement of the coil in the optical axis direction is performed by the two support bodies and the magnet. It is preferable that a limiting space is formed.

  In this way, the space that restricts the movement of the coil in the optical axis direction is formed by the two supports and the magnet, and the space for the movement of the coil is secured, so the actuator can be further downsized. become.

  In order to solve the above problems, an imaging apparatus according to the present invention includes the above-described actuator and an imaging element that converts an image formed by an optical member into an electrical signal. As a result, it is possible to realize an imaging device that is excellent in impact resistance and is reduced in size and thickness.

  In order to solve the above-described problems, an electronic apparatus according to the present invention includes the above-described imaging apparatus. As a result, it is possible to realize an electronic device that has excellent impact resistance and is equipped with a small and thin imaging device.

  In the actuator according to the present invention, as described above, a spherical body made of a nonmagnetic material is disposed in the gap between the holder and the support, and the spherical body moves in the optical axis direction of the holder. Thus, the configuration is adapted to rotate.

  Moreover, the imaging device according to the present invention has a configuration including the actuator as described above.

  Moreover, the electronic device according to the present invention has the above-described imaging device as described above.

  Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is excellent in impact resistance, and the imaging device can be reduced in size and thickness.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. The present invention is not limited to this.

  1 to 3 show a configuration of a main part of an actuator according to the present embodiment (hereinafter referred to as the present actuator), FIG. 1 is an exploded perspective view, FIG. 2 is a perspective view, and FIG. 3 is a sectional view. is there.

  As shown in FIGS. 1 to 3, the actuator includes an upper guide (support body; first support body) 9, a leaf spring (elastic member) 11, a magnet 12, a yoke (magnetic body) 13, a coil 14, A holder 15 that holds the optical member 16, a spherical body 17, and a base (support body; second support body) 18 are provided.

  This actuator is used for autofocusing of an imaging device mounted on a mobile electronic device such as a mobile phone. In other words, the present actuator forms an image of an object to be imaged by the imaging device by the optical member 16. Then, the image formed by the optical member 16 is converted into an electric signal by the image sensor 19. In this specification, the direction in which the optical member 16 forms an object (the direction of a straight line connecting the optical member 16 and the object) is referred to as an “optical axis direction”. In this “optical axis direction”, the object side to be imaged is simply referred to as “object side”, and the side opposite to the object side is referred to as “image plane side”.

  The yoke 13 has a cylindrical shape. A holder 15 is disposed so as to be accommodated in the cylindrical shape of the yoke 13. That is, the yoke 13 is disposed around the holder 15. A cylindrical magnet 12 is fixed to the inner wall of the cylindrical yoke 13 with an adhesive. The holder 15 that holds the optical member 16 is fixed integrally with the coil 14 so as to be accommodated in the coil 14.

  In the present actuator, the magnet 12, the yoke 13, and the coil 14 constitute a magnetic circuit. That is, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14. Due to this electromagnetic induction phenomenon, thrust in the optical axis direction is generated with respect to the holder 15 that is integrally fixed to the coil 14. The holder 15 moves in the optical axis direction by this thrust. Further, the thrust generated in the holder 15 is proportional to the amount of current applied to the coil 14.

  An upper guide 9 and a base 18 are provided with the magnet 12, the yoke 13, and the coil 14 sandwiched in the optical axis direction. The upper guide 9 is disposed on the object side, and the base 18 is disposed on the image plane side. Insertion grooves 9a and 18a are formed in the upper guide 9 and the base 18, respectively, so that the holder 15 fixed integrally with the coil 14 can move in the optical axis direction. The base 18 has a yoke 13 fixed to the object side and an image sensor 19 fixed to the image plane side. The upper guide 9 is fixed to the base 18 and the yoke 13.

  As shown in FIG. 3, in this actuator, a space is formed by the upper guide 9, the magnet 12, and the base 18, and the coil 14 is accommodated in this space. Therefore, when the holder 15 moves in the optical axis direction, the coil 14 fixed to the holder 15 abuts on the image plane side surface of the upper guide 9, thereby restricting movement on the object side in the optical axis direction. The Further, the coil 14 is in contact with the object-side surface of the base 18, so that the movement on the image plane side in the optical axis direction is limited. That is, the upper guide 9 and the base 18 have a function of limiting the movement of the coil 14 in the optical axis direction.

  In the configuration shown in FIG. 3, the movement of the holder 15 in the optical axis direction is restricted by the coil 14 coming into contact with the upper guide 9 and the base 18, but the movement of the holder 15 in the optical axis direction is restricted. The configuration to be performed is not limited to the configuration shown in FIG. For example, a configuration in which a part of the holder 15 is in contact with the upper guide 9 and the base 18 may be employed. Specifically, a stopper portion capable of contacting the upper guide 9 and the base 18 is provided on the side surface of the holder 15, and the movement of the holder 15 in the optical axis direction is limited by the stopper portion. In this configuration, the coil 14 is not in direct contact with the upper guide 9 and the base 18, and deformation of the coil 14 and coating of the coil wire can be prevented.

  On the other hand, this actuator is structured such that the movement of the holder 15 holding the optical member 16 in the optical axis direction is guided by the insertion grooves formed in both the upper guide 9 and the base 18. Therefore, for the holder 15, the upper guide 9 and the base 18 (insertion grooves formed on both) have a function as a guide portion that guides the movement of the holder 15 in the optical axis direction.

  The present actuator is characterized in that the spherical body 17 is disposed so as to contact the side surface of the holder 15 (when the surfaces aligned in the optical axis direction are the upper surface and the lower surface). The spherical body 17 rotates by friction with the side surface of the holder 15 when the holder 15 moves in the optical axis direction. The holder 15 can be supported by the frictional force generated by the rotation of the spherical body 17 with respect to the movement in the optical axis direction. On the other hand, the displacement of the holder 15 in the direction perpendicular to the optical axis direction is restricted by the spherical body 17 in contact with the side surface of the holder 15.

  In this actuator, the spherical body 17 in contact with the side surface of the holder 15 is used to support the holder 15 in the optical axis direction. Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  That is, in the conventional actuator, the holder is fixedly supported by a pair of leaf springs, and the movement of the holder in the optical axis direction is supported by the pair of leaf springs. Therefore, when the actuator is downsized, the spring constant of the leaf spring has to be reduced (the volume of the magnetic circuit portion is reduced). Therefore, in the conventional actuator, as the size of the actuator is reduced, the strength of the leaf spring decreases, and there arises a problem that the impact resistance against dropping of the imaging device for portable electronic devices is reduced.

  On the other hand, in this actuator, movement of the holder 15 in the optical axis direction is supported by a spherical body 17 that is in contact with the side surface thereof, and is not fixedly supported by a pair of leaf springs as in the prior art (fixed and supported by the holder). A pair of leaf springs themselves are not provided). Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and a member that supports (regulates) displacement in directions other than the optical axis direction is provided. It wasn't. On the other hand, in this actuator, the spherical body 17 regulates the displacement of the holder 15 in a direction other than the optical axis direction. Therefore, as compared with the conventional actuator, the holder 15 does not vibrate in directions other than the optical axis direction due to the impact generated when the imaging device for portable electronic devices is dropped.

  In this actuator, if the spherical body 17 is arranged so as to contact the side surface of the holder 15, a frictional force is generated between the spherical body 17 and the side surface of the holder 15 when the holder 15 moves in the optical axis direction. Arise. Therefore, the present actuator is not particularly limited as long as the spherical body 17 is arranged so as to be in contact with the side surface of the holder 15.

  Further, the spherical body provided in the actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on both sides of the object side and the image plane side on the holder side surface. A configuration in which two spherical bodies are arranged on both the object side and the image plane side is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, when the contact area between the spherical body 17 and the side surface of the holder 15 increases, the frictional force generated on the side surface of the holder 15 increases. That is, in this actuator, the strength of the support support for moving the holder 15 in the optical axis direction is proportional to the frictional force (contact area) generated between the spherical body 17 and the side surface of the holder 15. Therefore, a configuration corresponding to the volume of the magnetic circuit portion of the actuator and the amount of current applied to the magnetic circuit can be realized by appropriately setting the contact area between the spherical body 17 and the side surface of the holder 15.

  In addition, the present actuator preferably has a configuration in which the spherical bodies are separated so as to sandwich the holder 15 when viewed from the optical axis direction. With such a configuration, the contact surface between the spherical body 17 and the side surface of the holder 15 is arranged at a position symmetrical with respect to the optical axis (center axis) of the holder 15 and is supported in a direction perpendicular to the optical axis direction. There is no bias and more accurate movement support in the optical axis direction is possible.

  Further, the spherical body 17 in the present actuator is preferably made of a material that does not affect the arrangement in a strong magnetic field and does not affect the magnetic flux distribution by the magnetic circuit, that is, a nonmagnetic material. Examples of the material of the spherical body 17 include ceramic, brass, glass, nonmagnetic stainless steel, and the like.

  An example of the number and arrangement of the spherical bodies 17 in this actuator is shown in FIGS. As shown in FIG. 3, the spherical body 17 is disposed in the gap between the base 18 and the holder 15, on which the yoke 13 is fixed on the object side. Three spherical bodies 17 are arranged, and as shown in FIG. 1, the holders 15 are arranged between the three spherical bodies 17 in the optical axis direction. That is, each of the three spherical bodies 17 is arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction (the figure formed by connecting the three spherical bodies 17 is an equilateral triangle. ing).

  The spherical body 17 is also disposed in the gap between the upper guide 9 and the holder 15. Similarly to the arrangement of the spherical bodies 17 in the gap between the base 18 and the holder 15, the three spherical bodies 17 are each arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction.

  Furthermore, the recessed part 15a is formed in the position which opposes the upper guide 9 and the base 18 in the holder 15 side surface, respectively. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15a and the inner wall of the insertion groove 9a of the upper guide 9. Similarly, the spherical body 17 is accommodated in a space formed by the inner wall of the recessed portion 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, Will be more reliable. In addition, the actuator can be miniaturized.

  In this actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner walls of the insertion grooves 9a and 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion grooves 9a and 18a are in contact with each other, a frictional force is generated between them, and there is a possibility that the movement of the holder 15 in the optical axis direction is hindered. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the optical axis direction within the insertion grooves 9a and 18a.

  In the present actuator, the leaf spring 11 is disposed on the object side of the holder 15. The leaf spring 11 is supported and fixed by the upper guide 9. The leaf spring 11 is in contact with the object-side surface of the holder 15 that moves in the optical axis direction. The leaf spring 11 applies a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. That is, the leaf spring 11 generates an elastic force proportional to the amount of movement of the holder 15 that moves in the optical axis direction. In this actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the position of the holder 15 and the current value applied to the coil 14 have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the present actuator, it is not necessary to perform special position control (for example, a separate position sensor) different from the conventional one due to the configuration in which the spherical body 17 is arranged. That is, in this actuator, the position control of the holder 15 can be performed in the same manner as the position control of the holder adopted in the conventional actuator. Therefore, it is possible to reduce the cost and size of the imaging device.

  As described above, in the present actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the shape of the leaf spring 11 changes according to the focal position of the optical member 16 (specifically, the lens) held by the holder 15. That is, in this actuator, the position of the optical member 16 is set according to the position of the object to be imaged by the imaging device. Here, as an example, when the object to be imaged is relatively far from the actuator, the optical member 16 is configured to move to the optical axis direction image plane side (so-called Inf state; infinity state). On the other hand, when the object to be imaged is relatively close to the actuator, the optical member 16 is configured to move toward the object side in the optical axis direction (so-called macro state; close-up photographing state). The configuration shown in FIG. 3 shows, as an example, the shape change of the leaf spring 11 when the optical member 16 changes between the Inf state and the macro state.

  The leaf spring 11 shown in FIG. 3 is a deformation when changing only the leaf spring 11 from the state fixed to the holder 15 to confirm the change of the leaf spring 11 in this actuator. is there.

  Note that which position of the optical member 16 is to be in the Inf state or the macro state is appropriately determined according to the optical design of the actuator.

  Further, the leaf spring 11 may be in contact with the object-side surface of the holder 15 and apply a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. In the present actuator, since the holder 15 is supported by the spherical body 17, it is not necessary to have a configuration in which the holder 15 is fixedly supported by the leaf spring 11 as in the conventional actuator. Therefore, the leaf spring 11 may be slidably in contact with the holder 15 that moves in the optical axis direction (the contact between the holder 15 and the leaf spring 11 as the holder 15 moves in the optical axis direction toward the object side). Part will fluctuate). In such a case, compared to a configuration in which the holder 15 is fixedly supported by the leaf spring 11, plastic deformation of the leaf spring 11 due to the vibration of the holder 15 when the imaging device for portable electronic device is dropped is further reduced.

  This actuator has the following effects because the holder 15 is held in contact with the spherical body 17. That is, this actuator has an effect of reducing the vibration amplitude of the holder 15 and shortening the vibration convergence time as compared with the conventional actuator.

  FIG. 4 is a graph showing the behavior (current-displacement characteristics) of a holder in a conventional actuator. FIG. 5 is a graph showing the behavior (current-displacement characteristics) of the holder in this actuator. The graphs of FIGS. 4 and 5 show the behavior of the holder when current steps of 10 mA (current steps of 30 mA, 40 mA,..., 80 mA) are applied to the magnetic circuit of the actuator. The horizontal axis of the graph is time, and the timing and application time when the current of each step of the current step is applied can be known. The vertical axis of the graph indicates the displacement of the holder in the optical axis direction when the current of each step of the current step is applied. 4 and 5 that the holder vibrates in the optical axis direction when a current of each step of the current step is applied to the actuator.

  In a conventional actuator, when a current step is applied, the holder vibrates, and it takes time for the vibration to converge. In the graph shown in FIG. 4, when a current step of 10 mA was applied, the vibration amplitude of the holder was 30 μm, and the vibration convergence time for the vibration amplitude to converge was about 90 ms. That is, in the conventional actuator, about 90 ms is required to converge the vibration in the optical axis direction of the holder.

  On the other hand, since this holder is held in a state where the holder 15 is in contact with the spherical body 17, the vibration of the holder seen in the conventional actuator can be suppressed and the vibration convergence time can be shortened. In the graph shown in FIG. 5, the vibration amplitude of the holder is 16 μm, and the vibration convergence time for the vibration amplitude to converge is about 15 ms. In this actuator, compared with the conventional actuator, the vibration convergence time is about 1/6, and the vibration amplitude is also about 1/2.

  Therefore, the present actuator can shorten the time required for the holder position to be stabilized as compared with the conventional actuator. Such shortening of the holder position stabilization time contributes to, for example, speeding up the autofocus operation.

  Further, the present actuator is not limited to the configuration in which only the spherical body 17 supports the movement of the holder 15 in the optical axis direction. A configuration in which movement of the holder 15 in the optical axis direction is supported by both the spherical body 17 and the leaf spring 11 may be employed. In other words, the holder 15 may be fixedly supported by the leaf spring 11. In the conventional actuator, two leaf springs 10 are necessary to fix and support the holder 15. On the other hand, since the spherical body 17 is used for supporting the movement of the holder 15 in the optical axis direction, only one leaf spring 11 for fixing and supporting the holder 15 is required. Therefore, even if the same spring constant is set for the leaf spring 11, the strength of the leaf spring 11 per unit increases as compared with a conventional actuator using two leaf springs. The resistance of the leaf spring 11 when the device is dropped can be increased. In this case, the spherical body 17 close to the object side to which the leaf spring 11 and the holder 15 are fixed may be omitted.

  This actuator can be expressed as having the following configuration. That is, an imaging element, an optical member that inputs a video signal to the imaging element, a holder that holds the optical member, a coil that is provided on the outer periphery of the holder, and a magnet that is provided around the coil In addition, in the actuator in which the magnetic body is fixed to the base that fixes the imaging device, the holder is connected to the gap between the holder and the base via a sphere made of a nonmagnetic material so that the holder can move in the optical axis direction. It can be expressed that it is a configured.

  Furthermore, this actuator can be expressed as a configuration in which a magnetic body having ferromagnetism is attached to the base, and a magnet is provided on one surface of the magnetic body.

(Modification 1)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 6 is a cross-sectional view showing the main configuration of the present actuator as the first modification. The configuration shown in FIGS. 1 to 3 is a configuration in which a cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, the present actuator may be configured not to include the yoke 13 as in the first modification shown in FIG.

  As shown in FIG. 6, the magnetic circuit in the actuator of the first modification includes a magnet 12 and a coil 14. The holder 15 that holds the optical member is fixed integrally with the coil 14 so as to be accommodated in the coil 14. A cylindrical magnet 12 is disposed so as to surround the outer periphery of the coil 14. And in the magnetic circuit of the actuator of the modification 1, the member arranged on the outermost periphery is the magnet 12.

(Modification 2)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 7 is a cross-sectional view showing a main configuration of the actuator as the second modification. The configuration shown in FIGS. 1 to 3 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, the present actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 2 shown in FIG.

  As shown in FIG. 7, the magnetic circuit in the actuator of the second modification includes a magnet 12, a yoke 13, and a coil 14. And the magnet 12 is hold | maintained integrally with the holder 15 holding an optical member. The coil 14 is disposed around the magnet 12. That is, the coil 14 is disposed so as to accommodate the magnet 12 and the holder 15. The coil 14 is fixed to the inner wall of the yoke 13.

  In the actuator of the second modification, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, and the optical axis direction is relative to the holder 15 that is integrally fixed to the magnet 12. The thrust is generated.

  Compared with the configuration shown in FIGS. 1 to 3, the actuator of Modification 2 does not need to provide a power supply wire in the holder 15 as a movable part, and thus the structure can be simplified. Play.

  Considering the configurations of the first and second modifications, the actuator can be expressed as having the following configuration. That is, an optical member that forms an image of an object to be imaged, and one of a coil and a magnet that are used to move the optical member in the optical axis direction, and a holder that holds the optical member And a support that supports the other of the coil and the magnet, and the holder and the support, and the holder can be moved in the optical axis direction relative to the support by rotating. It can be expressed as a configuration including a spherical body.

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, for convenience of explanation, members having the same functions as those described in Embodiment 1 are given the same numbers, and explanation thereof is omitted.

  8 and 9 show the configuration of the main part of the actuator of the present embodiment (hereinafter referred to as the present actuator), FIG. 8 is an exploded perspective view, and FIG. 9 is a cross-sectional view.

  In the actuator of the first embodiment, the spherical body 17 is arranged in the gap between the base 18 and the holder 15 and the gap between the upper guide 9 and the holder 15. On the other hand, as shown in FIGS. 8 and 9, the present actuator has a configuration in which the spherical body 17 is disposed only in the gap between the base 18 and the holder 15. A plurality of spherical bodies 17 are arranged in contact with the side surface of the holder 15. A plane perpendicular to the optical axis direction is formed by the individual spherical bodies 17. In other words, the individual spherical bodies 17 are arranged on the same plane perpendicular to the optical axis direction.

  The leaf spring 11 is fixed and supported by the upper guide 9. The upper guide 9 functions as an elastic member fixing portion that fixes and supports the leaf spring 11. Further, only one leaf spring 11 is disposed apart from the plane formed by the individual spherical bodies 17 in the optical axis direction. Therefore, the following effects can be obtained as compared with the conventional actuator in which the holder is fixedly supported by a pair (a plurality) of leaf springs.

  That is, in the conventional configuration, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by two leaf springs. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction.

  On the other hand, this actuator has a configuration in which the holder 15 is supported by one leaf spring 11, and is not a configuration in which the holder is fixedly supported by a plurality of leaf springs as in the conventional configuration. Therefore, the spring constant necessary for supporting the holder 15 to move in the optical axis direction can be designed with the spring constant of one leaf spring 11. For this reason, compared with the conventional structure, the spring constant of the leaf | plate spring 11 can be designed largely, and intensity | strength can be enlarged. Even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  Further, the spherical body 17 provided in the present actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on either the object side or the image plane side across the coil 14 on the side surface of the holder 15. A configuration in which two spherical bodies are arranged is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, a recess 15 a is formed at a position facing the base 18 on the side surface of the holder 15. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, the holder 15 side surface, the spherical body 17, and Will be more reliable. In addition, the actuator can be miniaturized. In addition, although it demonstrated as a structure which formed the hollow part here, considering the productivity more, it is good also as a structure which formed the hole part which can be easily inserted from an upper surface or a lower surface. In order to prevent the spherical body from being detached from the hole portion, a configuration may be adopted in which an inclination or the like is provided in the hole portion or a cover for closing the hole portion is provided.

  In the present actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner wall of the insertion groove 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion groove 18a are in contact with each other, a frictional force is generated by sliding between the two, and this sliding frictional force is much larger than the frictional force due to rolling of the spherical body. For this reason, compared with the present actuator in which the spherical body 17 is arranged, there is a possibility that the movement of the holder 15 in the optical axis direction is hindered by 10 to several tens of times. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the insertion groove 18a in the optical axis direction.

  In addition, the structure of the modification 1 and 2 of the said Embodiment 1 can be applied to this actuator. A specific modification thereof will be described below.

(Modification 3)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 10 is a cross-sectional view showing the main configuration of the actuator as the third modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, this actuator may be configured not to include the yoke 13 as in the third modification shown in FIG.

(Modification 4)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 11 is a cross-sectional view showing the main configuration of the actuator as the fourth modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, this actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 4 shown in FIG.

  In addition, about this actuator, the structure by which the spherical body 17 was distribute | arranged only to the clearance gap between the base 18 and the holder 15 has been demonstrated. However, the present actuator is not limited to this configuration, and may be a configuration arranged in the gap between the upper guide 9 and the holder 15.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The actuator of the present invention and the imaging device equipped with the actuator can be applied to all devices such as a camera mounted on a portable electronic device, and the actuator can be made smaller, thinner, and improved in impact resistance. Become. In addition, the actuator of the present invention and the imaging device including the actuator are not limited to portable electronic devices, and can be applied to, for example, in-car cameras and other applications that have a large impact and other electronic devices.

It is a disassembled perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is a perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the actuator of one Embodiment of this invention. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the conventional actuator. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is a disassembled perspective view which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the conventional actuator.

Explanation of symbols

9 Upper guide (support)
9a Insertion groove 10 Leaf spring 11 Leaf spring (elastic member)
12 Magnet 13 Yoke (magnetic material)
14 Coil 15 Holder 15a Recess 16 Optical member 17 Ball 18 Base (support)
18a Insertion groove 19 Image sensor

  The present invention relates to an actuator provided with a magnetic circuit composed of a magnet, a coil, and a magnetic body, an imaging device, and an electronic device.

  In recent years, a camera built in a portable electronic device has been improved in image quality, and the number of pixels of an image sensor has been increased. In such portable electronic devices, there is often a tendency to mount an autofocus function necessary for improving image quality on an imaging device (camera). In order to perform autofocus, it is generally necessary to move the internal optical system. Here, a magnetic circuit using a magnet and a coil is used as an actuator for driving the optical system. As a system for driving the optical system, a voice coil system for driving a coil or a magnet due to an electromagnetic induction phenomenon by a magnetic circuit is widely used.

  In a voice coil actuator, as a method of supporting a holder that holds an optical system, a method of forming a parallel leaf spring by attaching two leaf springs to the holder is generally used. The parallel leaf spring is deformed by a thrust generated by an electromagnetic induction phenomenon when a current is applied to the coil, and the holder is displaced in the optical axis direction.

For example, Patent Document 1 discloses component arrangement in an auto-focus mechanism of an optical system using such a parallel leaf spring. Patent Document 1 proposes an autofocus actuator that supports an imaging lens movably in the optical axis direction.
JP 2006-50693 A (published February 16, 2006)

  However, when the actuator using the conventional parallel leaf spring disclosed in Patent Document 1 is reduced in projection area and thinned (the height in the optical axis direction is reduced), the following problems occur.

  That is, in the conventional actuator, the holder for holding the optical system is held by the parallel leaf spring. Therefore, when the actuator is downsized, the strength of the parallel leaf spring is lowered. Hereinafter, the reduction in the strength of the parallel leaf spring will be described in detail.

  First, a configuration of a voice coil actuator using a conventional parallel leaf spring will be described with reference to FIG. FIG. 12 is a cross-sectional view showing a main configuration of a conventional actuator.

  The actuator shown in FIG. 12 is used for autofocus of an imaging device mounted on a general portable electronic device. As shown in FIG. 12, the conventional actuator includes a pair of leaf springs 10, a cylindrical magnet 12, a cylindrical yoke 13, a coil 14, and a cylindrical holder 15 that holds an optical member 16. It has. A magnet 12 and a coil 14 are provided inside the cylindrical yoke 13. A holder 15 is fixed inside the coil 14. A pair of leaf springs 10 are provided on both sides of the holder 15 in the optical axis direction. The holder 15 is fixedly supported by the leaf spring 10 and can move in the optical axis direction when the leaf spring 10 is deformed. Here, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, so that the holder 15 moves in the arrow direction (optical axis direction) shown in FIG. 12. It has become.

  With the recent progress in downsizing and thinning of imaging devices for portable electronic devices, there has been a demand for downsizing and thinning of autofocus actuators themselves. In order to satisfy this requirement, the volume of the magnetic circuit portion in the actuator must be reduced. Therefore, when the actuator is reduced in size and thickness, there is a problem that the efficiency of the magnetic circuit is lowered. As a result, the thrust per current in the magnetic circuit is reduced. In order to cope with this decrease in thrust, in the voice coil actuator shown in FIG. 12, it is necessary to reduce the spring constant of the pair of leaf springs 10 that support the holder 15.

  Here, generally, as a method of reducing the spring constant of the leaf spring 10, (i) increasing the length of the spring portion, (ii) reducing the spring width, or (iii) the plate of the leaf spring 10 One method is to reduce the thickness.

  (i) The method of increasing the length of the spring portion has a problem that the projected area of the actuator becomes large. Therefore, it is difficult to adopt the above method (i) due to the limitation of the actuator size.

  Further, (ii) a technique of reducing the spring width or (iii) a technique of reducing the plate thickness of the leaf spring 10 leads to a decrease in strength of the leaf spring 10. As a result, when the method (ii) or (iii) is adopted, when the holder 15 vibrates in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped, the holder 15 is attached to the holder 15. There is a concern that the plate spring 10 is plastically deformed. Then, when the leaf spring 10 is plastically deformed, there is a possibility that an abnormal operation of the actuator may occur. Further, the tilt of the optical system with respect to the image sensor increases, and the captured image may be deteriorated.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an actuator, an imaging device, and an electronic device that are excellent in impact resistance and can realize downsizing and thinning of the imaging device. There is.

In order to solve the above problems, an actuator according to the present invention is an optical member that forms an image of an object to be imaged, a holder that holds the optical member, and an optical member that moves the optical member in the optical axis direction. An actuator comprising a magnetic circuit and a support for supporting the magnetic circuit, wherein the magnetic circuit comprises a coil and a magnet, one of the coil and the magnet being attached to the holder, and the other being the support. A spherical body is arranged in the gap between the holder and the support body, and the spherical body is rotated by movement of the holder in the optical axis direction . An elastic member that contacts the object side surface of the holder moving in the optical axis direction and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction is provided. Both the spherical body and the elastic member, is characterized in that the optical axis direction movement of the holder is supported.

  According to said structure, the spherical body is distribute | arranged to the clearance gap between the said holder and the said support body, and the said spherical body is rotated by the movement of the optical axis direction of the said holder. The actuator according to the present invention does not have a configuration in which the holder is fixedly supported by a pair of leaf springs and the movement of the holder in the optical axis direction is supported by the pair of leaf springs, unlike the conventional actuator. Therefore, the above-described configuration does not cause the problem of “decrease in strength of the pair of leaf springs that hold the holder fixedly” as in the conventional actuator.

  Therefore, according to the above configuration, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is possible to provide an actuator that is excellent in impact resistance and that can realize downsizing and thinning of the imaging device.

  In the actuator according to the present invention, an insertion groove through which the holder is inserted is formed in the support, and the spherical body is in contact with both the side surface of the holder and the inner wall surface of the insertion groove. It may be arranged.

  According to said structure, since the said spherical body is distribute | arranged so that both the side surface of the said holder and the inner wall face of the said insertion groove may be contacted, when a holder moves to an optical axis direction, The spherical body rotates by friction. And it becomes possible to support a holder with the frictional force by rotation of this spherical body with respect to the movement of an optical axis direction. On the other hand, the displacement in the direction perpendicular to the optical axis direction of the holder is restricted by the spherical body that is in contact with the side surface of the holder.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and no member that supports (regulates) displacement in directions other than the optical axis direction is provided. It was. On the other hand, according to said structure, the spherical body has controlled the displacement of directions other than the optical axis direction of a holder. Therefore, as compared with a conventional actuator, the holder does not vibrate in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped.

  In the actuator according to the present invention, it is preferable that a plurality of the spherical bodies are arranged, and the spherical bodies are in a positional relationship so as to be sandwiched between the holders when viewed from the optical axis direction.

  According to said structure, since the said spherical body is arranged in multiple numbers, the contact area of a spherical body and a holder side surface becomes large, and the frictional force which arises on a holder side surface becomes large. Moreover, since each spherical body is in a positional relationship so as to sandwich the holder when viewed from the optical axis direction, the contact surface between the spherical body and the side surface of the holder is on the optical axis (center axis) of the holder. However, the support is not biased in a direction perpendicular to the optical axis direction, and more accurate movement support in the optical axis direction is possible.

  In particular, the spherical bodies are preferably arranged on the same plane perpendicular to the optical axis direction. As a result, it is possible to more accurately support movement in the optical axis direction.

  In the actuator according to the present invention, a recess is formed on the side surface of the holder, and a space capable of accommodating the spherical body is formed by the inner wall surface of the recess and the support. It is preferable.

  According to said structure, since the space which can accommodate the said spherical body is formed by the inner wall surface of the said hollow part and the said support body, when a holder moves to an optical axis direction, a spherical body is a holder. The contact between the holder side surface and the spherical body becomes more reliable without leaving the side surface. In addition, the actuator can be miniaturized.

  In the actuator according to the present invention, the elastic member that contacts the object side surface of the holder moving in the optical axis direction and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. It is preferable to be provided.

  According to the above configuration, when the elastic member contacts the object-side surface of the holder that moves in the optical axis direction, an elastic force that is proportional to the amount of movement of the holder that moves in the optical axis direction is generated. In the above configuration, the position of the holder is held by the balance between the thrust generated in the holder by electromagnetic induction by the magnetic circuit and the elastic force generated in the elastic member. Therefore, the position of the holder and the current value applied to the coil have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the above configuration, it is not necessary to perform special position control (for example, providing a separate position sensor) different from the conventional one, and the conventionally used position control method can be diverted. Therefore, it is possible to reduce the cost and size of the imaging device.

  The elastic member is in contact with the object-side surface of the holder that moves in the optical axis direction, and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. Good. Since the holder is supported by the spherical body, it is not necessary to have a configuration in which the holder is fixedly supported by the leaf spring as in the conventional actuator.

  For example, it is preferable that the elastic member is slidably in contact with the holder that moves in the optical axis direction. Thereby, compared with the conventional structure by which the holder was fixedly supported by the leaf | plate spring, the plastic deformation of an elastic member by the vibration of the holder at the time of fall of the imaging device for portable electronic devices is reduced.

  In the actuator according to the present invention, a plurality of the spherical bodies are arranged, the spherical bodies are arranged on the same plane perpendicular to the optical axis direction, and the elastic member is arranged on the plane. On the other hand, it is preferable that they are spaced apart in the optical axis direction.

  According to said structure, in order to make the optical axis direction movement of the said holder by a magnetic circuit smooth, each spherical body is distribute | arranged on the same surface perpendicular | vertical with respect to the said optical axis direction, and only one The elastic member is disposed away from the plane in the optical axis direction.

  In the conventional actuator, since the holder is fixedly supported by a pair of leaf springs, that is, two leaf springs, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by the two leaf springs. Become. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction. On the other hand, according to said structure, since only one elastic member is arrange | positioned, the spring constant required for the optical axis direction movement support of a holder can be designed with the spring constant of one elastic member. For this reason, compared to the conventional configuration, according to the above configuration, the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased. The problem of “decrease in strength of the pair of leaf springs to be held” does not occur.

  In the actuator according to the present invention, the support includes a first support that supports one end of the magnetic circuit in the optical axis direction, and a second support that supports the other end, and the spherical body. Is preferably arranged in any one of the gap between the holder and the first support and the gap between the holder and the second support. Even in such a configuration, since the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased, it is called “reduced strength of a pair of leaf springs that hold and hold the holder” like a conventional actuator. The problem does not invite.

  In the actuator according to the present invention, it is preferable that the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support.

  According to the above configuration, the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support body, so that the magnetic flux leakage of the magnet generated outside the actuator is reduced. Can do. Moreover, since the efficiency of the magnetic circuit of the actuator can be improved, the thrust per current can be improved.

  As described above, examples of the configuration of the magnetic circuit including the magnetic material having ferromagnetism include the following configurations.

  That is, in the actuator according to the present invention, the magnetic circuit may be configured by a coil provided on the outer periphery of the holder, the magnet disposed around the coil, and the magnetic body. With this configuration, the magnetic flux leakage of the magnet generated outside the actuator can be reduced.

  In the actuator according to the present invention, the magnetic circuit may include a magnet provided on an outer periphery of the holder, the coil disposed around the magnet, and the magnetic body.

  In particular, in the above configuration, since the magnet is provided on the outer periphery of the holder and the coil is arranged around the magnet, it is not necessary to provide a power supply wire in the holder as the movable part, and the structure can be simplified. There is an effect that can be.

  In the actuator according to the present invention, the spherical body is preferably made of a nonmagnetic material.

  Thus, since the spherical body is made of a nonmagnetic material, the spherical body does not affect the magnetic flux distribution by the magnetic circuit inside the actuator. Moreover, according to said structure, a spherical body does not adsorb | suck to a magnet in the case of an actuator assembly, and can improve an assembly workability | operativity.

  In the actuator according to the present invention, the two support bodies are provided with the magnet and the coil sandwiched in the optical axis direction, and the movement of the coil in the optical axis direction is performed by the two support bodies and the magnet. It is preferable that a limiting space is formed.

  In this way, the space that restricts the movement of the coil in the optical axis direction is formed by the two supports and the magnet, and the space for the movement of the coil is secured, so the actuator can be further downsized. become.

  In order to solve the above problems, an imaging apparatus according to the present invention includes the above-described actuator and an imaging element that converts an image formed by an optical member into an electrical signal. As a result, it is possible to realize an imaging device that is excellent in impact resistance and is reduced in size and thickness.

  In order to solve the above-described problems, an electronic apparatus according to the present invention includes the above-described imaging apparatus. As a result, it is possible to realize an electronic device that has excellent impact resistance and is equipped with a small and thin imaging device.

In the actuator according to the present invention, as described above, a spherical body made of a nonmagnetic material is disposed in the gap between the holder and the support, and the spherical body moves in the optical axis direction of the holder. The elastic member is configured to rotate and to contact the object-side surface of the holder that moves in the optical axis direction and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. A member is provided, and the movement of the holder in the optical axis direction is supported by both the spherical body and the elastic member .

  Moreover, the imaging device according to the present invention has a configuration including the actuator as described above.

  Moreover, the electronic device according to the present invention has the above-described imaging device as described above.

  Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is excellent in impact resistance, and the imaging device can be reduced in size and thickness.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. Note that the present invention is not limited to this.

  1 to 3 show a configuration of a main part of an actuator according to the present embodiment (hereinafter referred to as the present actuator), FIG. 1 is an exploded perspective view, FIG. 2 is a perspective view, and FIG. 3 is a sectional view. is there.

  As shown in FIGS. 1 to 3, the actuator includes an upper guide (support body; first support body) 9, a leaf spring (elastic member) 11, a magnet 12, a yoke (magnetic body) 13, a coil 14, A holder 15 that holds the optical member 16, a spherical body 17, and a base (support body; second support body) 18 are provided.

  This actuator is used for autofocusing of an imaging device mounted on a mobile electronic device such as a mobile phone. In other words, the present actuator forms an image of an object to be imaged by the imaging device by the optical member 16. Then, the image formed by the optical member 16 is converted into an electric signal by the image sensor 19. In this specification, the direction in which the optical member 16 forms an object (the direction of a straight line connecting the optical member 16 and the object) is referred to as an “optical axis direction”. In this “optical axis direction”, the object side to be imaged is simply referred to as “object side”, and the side opposite to the object side is referred to as “image plane side”.

  The yoke 13 has a cylindrical shape. A holder 15 is disposed so as to be accommodated in the cylindrical shape of the yoke 13. That is, the yoke 13 is disposed around the holder 15. A cylindrical magnet 12 is fixed to the inner wall of the cylindrical yoke 13 with an adhesive. The holder 15 that holds the optical member 16 is fixed integrally with the coil 14 so as to be accommodated in the coil 14.

  In the present actuator, the magnet 12, the yoke 13, and the coil 14 constitute a magnetic circuit. That is, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14. Due to this electromagnetic induction phenomenon, thrust in the optical axis direction is generated with respect to the holder 15 that is integrally fixed to the coil 14. The holder 15 moves in the optical axis direction by this thrust. Further, the thrust generated in the holder 15 is proportional to the amount of current applied to the coil 14.

  An upper guide 9 and a base 18 are provided with the magnet 12, the yoke 13, and the coil 14 sandwiched in the optical axis direction. The upper guide 9 is disposed on the object side, and the base 18 is disposed on the image plane side. Insertion grooves 9a and 18a are formed in the upper guide 9 and the base 18, respectively, so that the holder 15 fixed integrally with the coil 14 can move in the optical axis direction. The base 18 has a yoke 13 fixed to the object side and an image sensor 19 fixed to the image plane side. The upper guide 9 is fixed to the base 18 and the yoke 13.

  As shown in FIG. 3, in this actuator, a space is formed by the upper guide 9, the magnet 12, and the base 18, and the coil 14 is accommodated in this space. Therefore, when the holder 15 moves in the optical axis direction, the coil 14 fixed to the holder 15 abuts on the image plane side surface of the upper guide 9, thereby restricting movement on the object side in the optical axis direction. The Further, the coil 14 is in contact with the object-side surface of the base 18, so that the movement on the image plane side in the optical axis direction is limited. That is, the upper guide 9 and the base 18 have a function of limiting the movement of the coil 14 in the optical axis direction.

  In the configuration shown in FIG. 3, the movement of the holder 15 in the optical axis direction is restricted by the coil 14 coming into contact with the upper guide 9 and the base 18, but the movement of the holder 15 in the optical axis direction is restricted. The configuration to be performed is not limited to the configuration shown in FIG. For example, a configuration in which a part of the holder 15 is in contact with the upper guide 9 and the base 18 may be employed. Specifically, a stopper portion capable of contacting the upper guide 9 and the base 18 is provided on the side surface of the holder 15, and the movement of the holder 15 in the optical axis direction is limited by the stopper portion. In this configuration, the coil 14 is not in direct contact with the upper guide 9 and the base 18, and deformation of the coil 14 and coating of the coil wire can be prevented.

  On the other hand, this actuator is structured such that the movement of the holder 15 holding the optical member 16 in the optical axis direction is guided by the insertion grooves formed in both the upper guide 9 and the base 18. Therefore, for the holder 15, the upper guide 9 and the base 18 (insertion grooves formed on both) have a function as a guide portion that guides the movement of the holder 15 in the optical axis direction.

  The present actuator is characterized in that the spherical body 17 is disposed so as to contact the side surface of the holder 15 (when the surfaces aligned in the optical axis direction are the upper surface and the lower surface). The spherical body 17 rotates by friction with the side surface of the holder 15 when the holder 15 moves in the optical axis direction. The holder 15 can be supported by the frictional force generated by the rotation of the spherical body 17 with respect to the movement in the optical axis direction. On the other hand, the displacement of the holder 15 in the direction perpendicular to the optical axis direction is restricted by the spherical body 17 in contact with the side surface of the holder 15.

  In this actuator, the spherical body 17 in contact with the side surface of the holder 15 is used to support the holder 15 in the optical axis direction. Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  That is, in the conventional actuator, the holder is fixedly supported by a pair of leaf springs, and the movement of the holder in the optical axis direction is supported by the pair of leaf springs. Therefore, when the actuator is downsized, the spring constant of the leaf spring has to be reduced (the volume of the magnetic circuit portion is reduced). Therefore, in the conventional actuator, as the size of the actuator is reduced, the strength of the leaf spring decreases, and there arises a problem that the impact resistance against dropping of the imaging device for portable electronic devices is reduced.

  On the other hand, in this actuator, movement of the holder 15 in the optical axis direction is supported by a spherical body 17 that is in contact with the side surface thereof, and is not fixedly supported by a pair of leaf springs as in the prior art (fixed and supported by the holder). A pair of leaf springs themselves are not provided). Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and a member that supports (regulates) displacement in directions other than the optical axis direction is provided. It wasn't. On the other hand, in this actuator, the spherical body 17 regulates the displacement of the holder 15 in a direction other than the optical axis direction. Therefore, as compared with the conventional actuator, the holder 15 does not vibrate in directions other than the optical axis direction due to the impact generated when the imaging device for portable electronic devices is dropped.

  In this actuator, if the spherical body 17 is arranged so as to contact the side surface of the holder 15, a frictional force is generated between the spherical body 17 and the side surface of the holder 15 when the holder 15 moves in the optical axis direction. Arise. Therefore, the present actuator is not particularly limited as long as the spherical body 17 is arranged so as to be in contact with the side surface of the holder 15.

  Further, the spherical body provided in the actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on both sides of the object side and the image plane side on the holder side surface. A configuration in which two spherical bodies are arranged on both the object side and the image plane side is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, when the contact area between the spherical body 17 and the side surface of the holder 15 increases, the frictional force generated on the side surface of the holder 15 increases. That is, in this actuator, the strength of the support support for moving the holder 15 in the optical axis direction is proportional to the frictional force (contact area) generated between the spherical body 17 and the side surface of the holder 15. Therefore, a configuration corresponding to the volume of the magnetic circuit portion of the actuator and the amount of current applied to the magnetic circuit can be realized by appropriately setting the contact area between the spherical body 17 and the side surface of the holder 15.

  In addition, the present actuator preferably has a configuration in which the spherical bodies are separated so as to sandwich the holder 15 when viewed from the optical axis direction. With such a configuration, the contact surface between the spherical body 17 and the side surface of the holder 15 is arranged at a position symmetrical with respect to the optical axis (center axis) of the holder 15 and is supported in a direction perpendicular to the optical axis direction. There is no bias and more accurate movement support in the optical axis direction is possible.

  Further, the spherical body 17 in the present actuator is preferably made of a material that does not affect the arrangement in a strong magnetic field and does not affect the magnetic flux distribution by the magnetic circuit, that is, a nonmagnetic material. Examples of the material of the spherical body 17 include ceramic, brass, glass, nonmagnetic stainless steel, and the like.

  An example of the number and arrangement of the spherical bodies 17 in this actuator is shown in FIGS. As shown in FIG. 3, the spherical body 17 is disposed in the gap between the base 18 and the holder 15, on which the yoke 13 is fixed on the object side. Three spherical bodies 17 are arranged, and as shown in FIG. 1, the holders 15 are arranged between the three spherical bodies 17 in the optical axis direction. That is, each of the three spherical bodies 17 is arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction (the figure formed by connecting the three spherical bodies 17 is an equilateral triangle. ing).

  The spherical body 17 is also disposed in the gap between the upper guide 9 and the holder 15. Similarly to the arrangement of the spherical bodies 17 in the gap between the base 18 and the holder 15, the three spherical bodies 17 are each arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction.

  Furthermore, the recessed part 15a is formed in the position which opposes the upper guide 9 and the base 18 in the holder 15 side surface, respectively. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15a and the inner wall of the insertion groove 9a of the upper guide 9. Similarly, the spherical body 17 is accommodated in a space formed by the inner wall of the recessed portion 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, the holder 15 side surface, the spherical body 17, and Will be more reliable. In addition, the actuator can be miniaturized.

  In this actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner walls of the insertion grooves 9a and 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion grooves 9a and 18a are in contact with each other, a frictional force is generated between them, and there is a possibility that the movement of the holder 15 in the optical axis direction is hindered. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the optical axis direction within the insertion grooves 9a and 18a.

  In the present actuator, the leaf spring 11 is disposed on the object side of the holder 15. The leaf spring 11 is supported and fixed by the upper guide 9. The leaf spring 11 is in contact with the object-side surface of the holder 15 that moves in the optical axis direction. The leaf spring 11 applies a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. That is, the leaf spring 11 generates an elastic force proportional to the amount of movement of the holder 15 that moves in the optical axis direction. In this actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the position of the holder 15 and the current value applied to the coil 14 have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the present actuator, it is not necessary to perform special position control (for example, a separate position sensor) different from the conventional one due to the configuration in which the spherical body 17 is arranged. That is, in this actuator, the position control of the holder 15 can be performed in the same manner as the position control of the holder adopted in the conventional actuator. Therefore, it is possible to reduce the cost and size of the imaging device.

  As described above, in the present actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the shape of the leaf spring 11 changes according to the focal position of the optical member 16 (specifically, the lens) held by the holder 15. That is, in this actuator, the position of the optical member 16 is set according to the position of the object to be imaged by the imaging device. Here, as an example, when the object to be imaged is relatively far from the actuator, the optical member 16 is configured to move to the optical axis direction image plane side (so-called Inf state; infinity state). On the other hand, when the object to be imaged is relatively close to the actuator, the optical member 16 is configured to move toward the object side in the optical axis direction (so-called macro state; close-up photographing state). The configuration shown in FIG. 3 shows, as an example, the shape change of the leaf spring 11 when the optical member 16 changes between the Inf state and the macro state.

  The leaf spring 11 shown in FIG. 3 is a deformation when changing only the leaf spring 11 from the state fixed to the holder 15 to confirm the change of the leaf spring 11 in this actuator. is there.

  Note that which position of the optical member 16 is to be in the Inf state or the macro state is appropriately determined according to the optical design of the actuator.

  Further, the leaf spring 11 may be in contact with the object-side surface of the holder 15 and apply a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. In the present actuator, since the holder 15 is supported by the spherical body 17, it is not necessary to have a configuration in which the holder 15 is fixedly supported by the leaf spring 11 as in the conventional actuator. Therefore, the leaf spring 11 may be slidably in contact with the holder 15 that moves in the optical axis direction (the contact between the holder 15 and the leaf spring 11 as the holder 15 moves in the optical axis direction toward the object side). Part will fluctuate). In such a case, compared to a configuration in which the holder 15 is fixedly supported by the leaf spring 11, plastic deformation of the leaf spring 11 due to the vibration of the holder 15 when the imaging device for portable electronic device is dropped is further reduced.

  This actuator has the following effects because the holder 15 is held in contact with the spherical body 17. That is, this actuator has an effect of reducing the vibration amplitude of the holder 15 and shortening the vibration convergence time as compared with the conventional actuator.

  FIG. 4 is a graph showing the behavior (current-displacement characteristics) of a holder in a conventional actuator. FIG. 5 is a graph showing the behavior (current-displacement characteristics) of the holder in this actuator. The graphs of FIGS. 4 and 5 show the behavior of the holder when current steps of 10 mA (current steps of 30 mA, 40 mA,..., 80 mA) are applied to the magnetic circuit of the actuator. The horizontal axis of the graph is time, and the timing and application time when the current of each step of the current step is applied can be known. The vertical axis of the graph indicates the displacement of the holder in the optical axis direction when the current of each step of the current step is applied. 4 and 5 that the holder vibrates in the optical axis direction when a current of each step of the current step is applied to the actuator.

  In a conventional actuator, when a current step is applied, the holder vibrates, and it takes time for the vibration to converge. In the graph shown in FIG. 4, when a current step of 10 mA was applied, the vibration amplitude of the holder was 30 μm, and the vibration convergence time for the vibration amplitude to converge was about 90 ms. That is, in the conventional actuator, about 90 ms is required to converge the vibration in the optical axis direction of the holder.

  On the other hand, since this holder is held in a state where the holder 15 is in contact with the spherical body 17, the vibration of the holder seen in the conventional actuator can be suppressed and the vibration convergence time can be shortened. In the graph shown in FIG. 5, the vibration amplitude of the holder is 16 μm, and the vibration convergence time for the vibration amplitude to converge is about 15 ms. In this actuator, compared with the conventional actuator, the vibration convergence time is about 1/6, and the vibration amplitude is also about 1/2.

  Therefore, the present actuator can shorten the time required for the holder position to be stabilized as compared with the conventional actuator. Such shortening of the holder position stabilization time contributes to, for example, speeding up the autofocus operation.

  Further, the present actuator is not limited to the configuration in which only the spherical body 17 supports the movement of the holder 15 in the optical axis direction. A configuration in which movement of the holder 15 in the optical axis direction is supported by both the spherical body 17 and the leaf spring 11 may be employed. In other words, the holder 15 may be fixedly supported by the leaf spring 11. In the conventional actuator, two leaf springs 10 are necessary to fix and support the holder 15. On the other hand, since the spherical body 17 is used for supporting the movement of the holder 15 in the optical axis direction, only one leaf spring 11 for fixing and supporting the holder 15 is required. Therefore, even if the same spring constant is set for the leaf spring 11, the strength of the leaf spring 11 per unit increases as compared with a conventional actuator using two leaf springs. The resistance of the leaf spring 11 when the device is dropped can be increased. In this case, the spherical body 17 close to the object side to which the leaf spring 11 and the holder 15 are fixed may be omitted.

  This actuator can be expressed as having the following configuration. That is, an imaging element, an optical member that inputs a video signal to the imaging element, a holder that holds the optical member, a coil that is provided on the outer periphery of the holder, and a magnet that is provided around the coil In addition, in the actuator in which the magnetic body is fixed to the base that fixes the imaging device, the holder is connected to the gap between the holder and the base via a sphere made of a nonmagnetic material so that the holder can move in the optical axis direction. It can be expressed that it is a configured.

  Furthermore, this actuator can be expressed as a configuration in which a magnetic body having ferromagnetism is attached to the base, and a magnet is provided on one surface of the magnetic body.

(Modification 1)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 6 is a cross-sectional view showing the main configuration of the present actuator as the first modification. The configuration shown in FIGS. 1 to 3 is a configuration in which a cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, the present actuator may be configured not to include the yoke 13 as in the first modification shown in FIG.

  As shown in FIG. 6, the magnetic circuit in the actuator of the first modification includes a magnet 12 and a coil 14. The holder 15 that holds the optical member is fixed integrally with the coil 14 so as to be accommodated in the coil 14. A cylindrical magnet 12 is disposed so as to surround the outer periphery of the coil 14. And in the magnetic circuit of the actuator of the modification 1, the member arranged on the outermost periphery is the magnet 12.

(Modification 2)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 7 is a cross-sectional view showing a main configuration of the actuator as the second modification. The configuration shown in FIGS. 1 to 3 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, the present actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 2 shown in FIG.

  As shown in FIG. 7, the magnetic circuit in the actuator of the second modification includes a magnet 12, a yoke 13, and a coil 14. And the magnet 12 is hold | maintained integrally with the holder 15 holding an optical member. The coil 14 is disposed around the magnet 12. That is, the coil 14 is disposed so as to accommodate the magnet 12 and the holder 15. The coil 14 is fixed to the inner wall of the yoke 13.

  In the actuator of the second modification, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, and the optical axis direction is relative to the holder 15 that is integrally fixed to the magnet 12. The thrust is generated.

  Compared with the configuration shown in FIGS. 1 to 3, the actuator of Modification 2 does not need to provide a power supply wire in the holder 15 as a movable part, and thus the structure can be simplified. Play.

  Considering the configurations of the first and second modifications, the actuator can be expressed as having the following configuration. That is, an optical member that forms an image of an object to be imaged, and one of a coil and a magnet that are used to move the optical member in the optical axis direction, and a holder that holds the optical member And a support that supports the other of the coil and the magnet, and the holder and the support, and the holder can be moved in the optical axis direction relative to the support by rotating. It can be expressed as a configuration including a spherical body.

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, for convenience of explanation, members having the same functions as those described in Embodiment 1 are given the same numbers, and explanation thereof is omitted.

  8 and 9 show the configuration of the main part of the actuator of the present embodiment (hereinafter referred to as the present actuator), FIG. 8 is an exploded perspective view, and FIG. 9 is a cross-sectional view.

  In the actuator of the first embodiment, the spherical body 17 is arranged in the gap between the base 18 and the holder 15 and the gap between the upper guide 9 and the holder 15. On the other hand, as shown in FIGS. 8 and 9, the present actuator has a configuration in which the spherical body 17 is disposed only in the gap between the base 18 and the holder 15. A plurality of spherical bodies 17 are arranged in contact with the side surface of the holder 15. A plane perpendicular to the optical axis direction is formed by the individual spherical bodies 17. In other words, the individual spherical bodies 17 are arranged on the same plane perpendicular to the optical axis direction.

  The leaf spring 11 is fixed and supported by the upper guide 9. The upper guide 9 functions as an elastic member fixing portion that fixes and supports the leaf spring 11. Further, only one leaf spring 11 is disposed apart from the plane formed by the individual spherical bodies 17 in the optical axis direction. Therefore, the following effects can be obtained as compared with the conventional actuator in which the holder is fixedly supported by a pair (a plurality) of leaf springs.

  That is, in the conventional configuration, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by two leaf springs. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction.

  On the other hand, this actuator has a configuration in which the holder 15 is supported by one leaf spring 11, and is not a configuration in which the holder is fixedly supported by a plurality of leaf springs as in the conventional configuration. Therefore, the spring constant necessary for supporting the holder 15 to move in the optical axis direction can be designed with the spring constant of one leaf spring 11. For this reason, compared with the conventional structure, the spring constant of the leaf | plate spring 11 can be designed largely, and intensity | strength can be enlarged. Even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  Further, the spherical body 17 provided in the present actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on either the object side or the image plane side across the coil 14 on the side surface of the holder 15. A configuration in which two spherical bodies are arranged is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, a recess 15 a is formed at a position facing the base 18 on the side surface of the holder 15. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, the holder 15 side surface, the spherical body 17, and Will be more reliable. In addition, the actuator can be miniaturized. In addition, although it demonstrated as a structure which formed the hollow part here, considering the productivity more, it is good also as a structure which formed the hole part which can be easily inserted from an upper surface or a lower surface. In order to prevent the spherical body from being detached from the hole portion, a configuration may be adopted in which an inclination or the like is provided in the hole portion or a cover for closing the hole portion is provided.

  In the present actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner wall of the insertion groove 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion groove 18a are in contact with each other, a frictional force is generated by sliding between the two, and this sliding frictional force is much larger than the frictional force due to rolling of the spherical body. For this reason, compared with the present actuator in which the spherical body 17 is arranged, there is a possibility that the movement of the holder 15 in the optical axis direction is hindered by 10 to several tens of times. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the insertion groove 18a in the optical axis direction.

  In addition, the structure of the modification 1 and 2 of the said Embodiment 1 can be applied to this actuator. A specific modification thereof will be described below.

(Modification 3)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 10 is a cross-sectional view showing the main configuration of the actuator as the third modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, this actuator may be configured not to include the yoke 13 as in the third modification shown in FIG.

(Modification 4)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 11 is a cross-sectional view showing the main configuration of the actuator as the fourth modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, this actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 4 shown in FIG.

  In addition, about this actuator, the structure by which the spherical body 17 was distribute | arranged only to the clearance gap between the base 18 and the holder 15 has been demonstrated. However, the present actuator is not limited to this configuration, and may be a configuration arranged in the gap between the upper guide 9 and the holder 15.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The actuator of the present invention and the imaging device equipped with the actuator can be applied to all devices such as a camera mounted on a portable electronic device, and the actuator can be made smaller, thinner, and improved in impact resistance. Become. In addition, the actuator of the present invention and the imaging device including the actuator are not limited to portable electronic devices, and can be applied to, for example, in-car cameras and other applications that have a large impact and other electronic devices.

It is a disassembled perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is a perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the actuator of one Embodiment of this invention. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the conventional actuator. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is a disassembled perspective view which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the conventional actuator.

Explanation of symbols

9 Upper guide (support)
9a Insertion groove 10 Leaf spring 11 Leaf spring (elastic member)
12 Magnet 13 Yoke (magnetic material)
14 Coil 15 Holder 15a Recess 16 Optical member 17 Ball 18 Base (support)
18a Insertion groove 19 Image sensor

  The present invention relates to an actuator provided with a magnetic circuit composed of a magnet, a coil, and a magnetic body, an imaging device, and an electronic device.

  In recent years, a camera built in a portable electronic device has been improved in image quality, and the number of pixels of an image sensor has been increased. In such portable electronic devices, there is often a tendency to mount an autofocus function necessary for improving image quality on an imaging device (camera). In order to perform autofocus, it is generally necessary to move the internal optical system. Here, a magnetic circuit using a magnet and a coil is used as an actuator for driving the optical system. As a system for driving the optical system, a voice coil system for driving a coil or a magnet due to an electromagnetic induction phenomenon by a magnetic circuit is widely used.

  In a voice coil actuator, as a method of supporting a holder that holds an optical system, a method of forming a parallel leaf spring by attaching two leaf springs to the holder is generally used. The parallel leaf spring is deformed by a thrust generated by an electromagnetic induction phenomenon when a current is applied to the coil, and the holder is displaced in the optical axis direction.

For example, Patent Document 1 discloses component arrangement in an auto-focus mechanism of an optical system using such a parallel leaf spring. Patent Document 1 proposes an autofocus actuator that supports an imaging lens movably in the optical axis direction.
JP 2006-50693 A (published February 16, 2006)

  However, when the actuator using the conventional parallel leaf spring disclosed in Patent Document 1 is reduced in projection area and thinned (the height in the optical axis direction is reduced), the following problems occur.

  That is, in the conventional actuator, the holder for holding the optical system is held by the parallel leaf spring. Therefore, when the actuator is downsized, the strength of the parallel leaf spring is lowered. Hereinafter, the reduction in the strength of the parallel leaf spring will be described in detail.

  First, a configuration of a voice coil actuator using a conventional parallel leaf spring will be described with reference to FIG. FIG. 12 is a cross-sectional view showing a main configuration of a conventional actuator.

  The actuator shown in FIG. 12 is used for autofocus of an imaging device mounted on a general portable electronic device. As shown in FIG. 12, the conventional actuator includes a pair of leaf springs 10, a cylindrical magnet 12, a cylindrical yoke 13, a coil 14, and a cylindrical holder 15 that holds an optical member 16. It has. A magnet 12 and a coil 14 are provided inside the cylindrical yoke 13. A holder 15 is fixed inside the coil 14. A pair of leaf springs 10 are provided on both sides of the holder 15 in the optical axis direction. The holder 15 is fixedly supported by the leaf spring 10 and can move in the optical axis direction when the leaf spring 10 is deformed. Here, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, so that the holder 15 moves in the arrow direction (optical axis direction) shown in FIG. 12. It has become.

  With the recent progress in downsizing and thinning of imaging devices for portable electronic devices, there has been a demand for downsizing and thinning of autofocus actuators themselves. In order to satisfy this requirement, the volume of the magnetic circuit portion in the actuator must be reduced. Therefore, when the actuator is reduced in size and thickness, there is a problem that the efficiency of the magnetic circuit is lowered. As a result, the thrust per current in the magnetic circuit is reduced. In order to cope with this decrease in thrust, in the voice coil actuator shown in FIG. 12, it is necessary to reduce the spring constant of the pair of leaf springs 10 that support the holder 15.

  Here, generally, as a method of reducing the spring constant of the leaf spring 10, (i) increasing the length of the spring portion, (ii) reducing the spring width, or (iii) the plate of the leaf spring 10 One method is to reduce the thickness.

  (i) The method of increasing the length of the spring portion has a problem that the projected area of the actuator becomes large. Therefore, it is difficult to adopt the above method (i) due to the limitation of the actuator size.

  Further, (ii) a technique of reducing the spring width or (iii) a technique of reducing the plate thickness of the leaf spring 10 leads to a decrease in strength of the leaf spring 10. As a result, when the method (ii) or (iii) is adopted, when the holder 15 vibrates in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped, the holder 15 is attached to the holder 15. There is a concern that the plate spring 10 is plastically deformed. Then, when the leaf spring 10 is plastically deformed, there is a possibility that an abnormal operation of the actuator may occur. Further, the tilt of the optical system with respect to the image sensor increases, and the captured image may be deteriorated.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an actuator, an imaging device, and an electronic device that are excellent in impact resistance and can realize downsizing and thinning of the imaging device. There is.

In order to solve the above problems, an actuator according to the present invention is an optical member that forms an image of an object to be imaged, a holder that holds the optical member, and an optical member that moves the optical member in the optical axis direction. An actuator comprising a magnetic circuit and a support for supporting the magnetic circuit, wherein the magnetic circuit comprises a coil and a magnet, one of the coil and the magnet being attached to the holder, and the other being the support. A spherical body is arranged in the gap between the holder and the support body, and the spherical body is rotated by movement of the holder in the optical axis direction. contacting the object side surface of the holder to be moved in the optical axis direction, and the holder with respect to, one elastic member providing an elastic force proportional to the amount of movement of the optical axis direction of the holder taken on the holder Vignetting and, by both the spherical body and the one elastic member, is characterized in that the optical axis direction movement of the holder is supported.

  According to said structure, the spherical body is distribute | arranged to the clearance gap between the said holder and the said support body, and the said spherical body is rotated by the movement of the optical axis direction of the said holder. The actuator according to the present invention does not have a configuration in which the holder is fixedly supported by a pair of leaf springs and the movement of the holder in the optical axis direction is supported by the pair of leaf springs, unlike the conventional actuator. Therefore, the above-described configuration does not cause the problem of “decrease in strength of the pair of leaf springs that hold the holder fixedly” as in the conventional actuator.

  Therefore, according to the above configuration, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is possible to provide an actuator that is excellent in impact resistance and that can realize downsizing and thinning of the imaging device.

  In the actuator according to the present invention, an insertion groove through which the holder is inserted is formed in the support, and the spherical body is in contact with both the side surface of the holder and the inner wall surface of the insertion groove. It may be arranged.

  According to said structure, since the said spherical body is distribute | arranged so that both the side surface of the said holder and the inner wall face of the said insertion groove may be contacted, when a holder moves to an optical axis direction, The spherical body rotates by friction. And it becomes possible to support a holder with the frictional force by rotation of this spherical body with respect to the movement of an optical axis direction. On the other hand, the displacement in the direction perpendicular to the optical axis direction of the holder is restricted by the spherical body that is in contact with the side surface of the holder.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and no member that supports (regulates) displacement in directions other than the optical axis direction is provided. It was. On the other hand, according to said structure, the spherical body has controlled the displacement of directions other than the optical axis direction of a holder. Therefore, as compared with a conventional actuator, the holder does not vibrate in a direction other than the optical axis direction due to an impact generated when the imaging device for portable electronic devices is dropped.

  In the actuator according to the present invention, it is preferable that a plurality of the spherical bodies are arranged, and the spherical bodies are in a positional relationship so as to be sandwiched between the holders when viewed from the optical axis direction.

  According to said structure, since the said spherical body is arranged in multiple numbers, the contact area of a spherical body and a holder side surface becomes large, and the frictional force which arises on a holder side surface becomes large. Moreover, since each spherical body is in a positional relationship so as to sandwich the holder when viewed from the optical axis direction, the contact surface between the spherical body and the side surface of the holder is on the optical axis (center axis) of the holder. However, the support is not biased in a direction perpendicular to the optical axis direction, and more accurate movement support in the optical axis direction is possible.

  In particular, the spherical bodies are preferably arranged on the same plane perpendicular to the optical axis direction. As a result, it is possible to more accurately support movement in the optical axis direction.

  In the actuator according to the present invention, a recess is formed on the side surface of the holder, and a space capable of accommodating the spherical body is formed by the inner wall surface of the recess and the support. It is preferable.

  According to said structure, since the space which can accommodate the said spherical body is formed by the inner wall surface of the said hollow part and the said support body, when a holder moves to an optical axis direction, a spherical body is a holder. The contact between the holder side surface and the spherical body becomes more reliable without leaving the side surface. In addition, the actuator can be miniaturized.

  In the actuator according to the present invention, the elastic member that contacts the object side surface of the holder moving in the optical axis direction and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. It is preferable to be provided.

  According to the above configuration, when the elastic member contacts the object-side surface of the holder that moves in the optical axis direction, an elastic force that is proportional to the amount of movement of the holder that moves in the optical axis direction is generated. In the above configuration, the position of the holder is held by the balance between the thrust generated in the holder by electromagnetic induction by the magnetic circuit and the elastic force generated in the elastic member. Therefore, the position of the holder and the current value applied to the coil have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the above configuration, it is not necessary to perform special position control (for example, providing a separate position sensor) different from the conventional one, and the conventionally used position control method can be diverted. Therefore, it is possible to reduce the cost and size of the imaging device.

  The elastic member is in contact with the object-side surface of the holder that moves in the optical axis direction, and gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction. Good. Since the holder is supported by the spherical body, it is not necessary to have a configuration in which the holder is fixedly supported by the leaf spring as in the conventional actuator.

  For example, it is preferable that the elastic member is slidably in contact with the holder that moves in the optical axis direction. Thereby, compared with the conventional structure by which the holder was fixedly supported by the leaf | plate spring, the plastic deformation of an elastic member by the vibration of the holder at the time of fall of the imaging device for portable electronic devices is reduced.

  In the actuator according to the present invention, a plurality of the spherical bodies are arranged, the spherical bodies are arranged on the same plane perpendicular to the optical axis direction, and the elastic member is arranged on the plane. On the other hand, it is preferable that they are spaced apart in the optical axis direction.

  According to said structure, in order to make the optical axis direction movement of the said holder by a magnetic circuit smooth, each spherical body is distribute | arranged on the same surface perpendicular | vertical with respect to the said optical axis direction, and only one The elastic member is disposed away from the plane in the optical axis direction.

  In the conventional actuator, since the holder is fixedly supported by a pair of leaf springs, that is, two leaf springs, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by the two leaf springs. Become. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction. On the other hand, according to said structure, since only one elastic member is arrange | positioned, the spring constant required for the optical axis direction movement support of a holder can be designed with the spring constant of one elastic member. For this reason, compared to the conventional configuration, according to the above configuration, the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased. The problem of “decrease in strength of the pair of leaf springs to be held” does not occur.

  In the actuator according to the present invention, the support includes a first support that supports one end of the magnetic circuit in the optical axis direction, and a second support that supports the other end, and the spherical body. Is preferably arranged in any one of the gap between the holder and the first support and the gap between the holder and the second support. Even in such a configuration, since the spring constant of the elastic member can be designed to be large and the strength of the elastic member can be increased, it is called “reduced strength of a pair of leaf springs that hold and hold the holder” like a conventional actuator. The problem does not invite.

  In the actuator according to the present invention, it is preferable that the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support.

  According to the above configuration, the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support body, so that the magnetic flux leakage of the magnet generated outside the actuator is reduced. Can do. Moreover, since the efficiency of the magnetic circuit of the actuator can be improved, the thrust per current can be improved.

  As described above, examples of the configuration of the magnetic circuit including the magnetic material having ferromagnetism include the following configurations.

  That is, in the actuator according to the present invention, the magnetic circuit may be configured by a coil provided on the outer periphery of the holder, the magnet disposed around the coil, and the magnetic body. With this configuration, the magnetic flux leakage of the magnet generated outside the actuator can be reduced.

  In the actuator according to the present invention, the magnetic circuit may include a magnet provided on an outer periphery of the holder, the coil disposed around the magnet, and the magnetic body.

  In particular, in the above configuration, since the magnet is provided on the outer periphery of the holder and the coil is arranged around the magnet, it is not necessary to provide a power supply wire in the holder as the movable part, and the structure can be simplified. There is an effect that can be.

  In the actuator according to the present invention, the spherical body is preferably made of a nonmagnetic material.

  Thus, since the spherical body is made of a nonmagnetic material, the spherical body does not affect the magnetic flux distribution by the magnetic circuit inside the actuator. Moreover, according to said structure, a spherical body does not adsorb | suck to a magnet in the case of an actuator assembly, and can improve an assembly workability | operativity.

  In the actuator according to the present invention, the two support bodies are provided with the magnet and the coil sandwiched in the optical axis direction, and the movement of the coil in the optical axis direction is performed by the two support bodies and the magnet. It is preferable that a limiting space is formed.

  In this way, the space that restricts the movement of the coil in the optical axis direction is formed by the two supports and the magnet, and the space for the movement of the coil is secured, so the actuator can be further downsized. become.

  In order to solve the above problems, an imaging apparatus according to the present invention includes the above-described actuator and an imaging element that converts an image formed by an optical member into an electrical signal. As a result, it is possible to realize an imaging device that is excellent in impact resistance and is reduced in size and thickness.

  In order to solve the above-described problems, an electronic apparatus according to the present invention includes the above-described imaging apparatus. As a result, it is possible to realize an electronic device that has excellent impact resistance and is equipped with a small and thin imaging device.

In the actuator according to the present invention, as described above, a spherical body made of a nonmagnetic material is disposed in the gap between the holder and the support, and the spherical body moves in the optical axis direction of the holder. Accordingly, providing with and rotates in contact with the object-side surface of the holder to be moved in the optical axis direction, and, with respect to the holder, the elastic force proportional to the amount of movement of the optical axis direction of the holder 1 One elastic member is attached to the holder, and the movement of the holder in the optical axis direction is supported by both the spherical body and the one elastic member.

  Moreover, the imaging device according to the present invention has a configuration including the actuator as described above.

  Moreover, the electronic device according to the present invention has the above-described imaging device as described above.

  Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance. That is, it is excellent in impact resistance, and the imaging device can be reduced in size and thickness.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. Note that the present invention is not limited to this.

  1 to 3 show a configuration of a main part of an actuator according to the present embodiment (hereinafter referred to as the present actuator), FIG. 1 is an exploded perspective view, FIG. 2 is a perspective view, and FIG. 3 is a sectional view. is there.

  As shown in FIGS. 1 to 3, the actuator includes an upper guide (support body; first support body) 9, a leaf spring (elastic member) 11, a magnet 12, a yoke (magnetic body) 13, a coil 14, A holder 15 that holds the optical member 16, a spherical body 17, and a base (support body; second support body) 18 are provided.

  This actuator is used for autofocusing of an imaging device mounted on a mobile electronic device such as a mobile phone. In other words, the present actuator forms an image of an object to be imaged by the imaging device by the optical member 16. Then, the image formed by the optical member 16 is converted into an electric signal by the image sensor 19. In this specification, the direction in which the optical member 16 forms an object (the direction of a straight line connecting the optical member 16 and the object) is referred to as an “optical axis direction”. In this “optical axis direction”, the object side to be imaged is simply referred to as “object side”, and the side opposite to the object side is referred to as “image plane side”.

  The yoke 13 has a cylindrical shape. A holder 15 is disposed so as to be accommodated in the cylindrical shape of the yoke 13. That is, the yoke 13 is disposed around the holder 15. A cylindrical magnet 12 is fixed to the inner wall of the cylindrical yoke 13 with an adhesive. The holder 15 that holds the optical member 16 is fixed integrally with the coil 14 so as to be accommodated in the coil 14.

  In the present actuator, the magnet 12, the yoke 13, and the coil 14 constitute a magnetic circuit. That is, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14. Due to this electromagnetic induction phenomenon, thrust in the optical axis direction is generated with respect to the holder 15 that is integrally fixed to the coil 14. The holder 15 moves in the optical axis direction by this thrust. Further, the thrust generated in the holder 15 is proportional to the amount of current applied to the coil 14.

  An upper guide 9 and a base 18 are provided with the magnet 12, the yoke 13, and the coil 14 sandwiched in the optical axis direction. The upper guide 9 is disposed on the object side, and the base 18 is disposed on the image plane side. Insertion grooves 9a and 18a are formed in the upper guide 9 and the base 18, respectively, so that the holder 15 fixed integrally with the coil 14 can move in the optical axis direction. The base 18 has a yoke 13 fixed to the object side and an image sensor 19 fixed to the image plane side. The upper guide 9 is fixed to the base 18 and the yoke 13.

  As shown in FIG. 3, in this actuator, a space is formed by the upper guide 9, the magnet 12, and the base 18, and the coil 14 is accommodated in this space. Therefore, when the holder 15 moves in the optical axis direction, the coil 14 fixed to the holder 15 abuts on the image plane side surface of the upper guide 9, thereby restricting movement on the object side in the optical axis direction. The Further, the coil 14 is in contact with the object-side surface of the base 18, so that the movement on the image plane side in the optical axis direction is limited. That is, the upper guide 9 and the base 18 have a function of limiting the movement of the coil 14 in the optical axis direction.

  In the configuration shown in FIG. 3, the movement of the holder 15 in the optical axis direction is restricted by the coil 14 coming into contact with the upper guide 9 and the base 18, but the movement of the holder 15 in the optical axis direction is restricted. The configuration to be performed is not limited to the configuration shown in FIG. For example, a configuration in which a part of the holder 15 is in contact with the upper guide 9 and the base 18 may be employed. Specifically, a stopper portion capable of contacting the upper guide 9 and the base 18 is provided on the side surface of the holder 15, and the movement of the holder 15 in the optical axis direction is limited by the stopper portion. In this configuration, the coil 14 is not in direct contact with the upper guide 9 and the base 18, and deformation of the coil 14 and coating of the coil wire can be prevented.

  On the other hand, this actuator is structured such that the movement of the holder 15 holding the optical member 16 in the optical axis direction is guided by the insertion grooves formed in both the upper guide 9 and the base 18. Therefore, for the holder 15, the upper guide 9 and the base 18 (insertion grooves formed on both) have a function as a guide portion that guides the movement of the holder 15 in the optical axis direction.

  The present actuator is characterized in that the spherical body 17 is disposed so as to contact the side surface of the holder 15 (when the surfaces aligned in the optical axis direction are the upper surface and the lower surface). The spherical body 17 rotates by friction with the side surface of the holder 15 when the holder 15 moves in the optical axis direction. The holder 15 can be supported by the frictional force generated by the rotation of the spherical body 17 with respect to the movement in the optical axis direction. On the other hand, the displacement of the holder 15 in the direction perpendicular to the optical axis direction is restricted by the spherical body 17 in contact with the side surface of the holder 15.

  In this actuator, the spherical body 17 in contact with the side surface of the holder 15 is used to support the holder 15 in the optical axis direction. Therefore, the problem of “decrease in the strength of the pair of leaf springs for fixing and holding the holder” unlike the conventional actuator does not occur.

  That is, in the conventional actuator, the holder is fixedly supported by a pair of leaf springs, and the movement of the holder in the optical axis direction is supported by the pair of leaf springs. Therefore, when the actuator is downsized, the spring constant of the leaf spring has to be reduced (the volume of the magnetic circuit portion is reduced). Therefore, in the conventional actuator, as the size of the actuator is reduced, the strength of the leaf spring decreases, and there arises a problem that the impact resistance against dropping of the imaging device for portable electronic devices is reduced.

  On the other hand, in this actuator, movement of the holder 15 in the optical axis direction is supported by a spherical body 17 that is in contact with the side surface thereof, and is not fixedly supported by a pair of leaf springs as in the prior art (fixed and supported by the holder). A pair of leaf springs themselves are not provided). Therefore, even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  In the conventional actuator, the pair of leaf springs supports only the movement of the holder in the optical axis direction, and a member that supports (regulates) displacement in directions other than the optical axis direction is provided. It wasn't. On the other hand, in this actuator, the spherical body 17 regulates the displacement of the holder 15 in a direction other than the optical axis direction. Therefore, as compared with the conventional actuator, the holder 15 does not vibrate in directions other than the optical axis direction due to the impact generated when the imaging device for portable electronic devices is dropped.

  In this actuator, if the spherical body 17 is arranged so as to contact the side surface of the holder 15, a frictional force is generated between the spherical body 17 and the side surface of the holder 15 when the holder 15 moves in the optical axis direction. Arise. Therefore, the present actuator is not particularly limited as long as the spherical body 17 is arranged so as to be in contact with the side surface of the holder 15.

  Further, the spherical body provided in the actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on both sides of the object side and the image plane side on the holder side surface. A configuration in which two spherical bodies are arranged on both the object side and the image plane side is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, when the contact area between the spherical body 17 and the side surface of the holder 15 increases, the frictional force generated on the side surface of the holder 15 increases. That is, in this actuator, the strength of the support support for moving the holder 15 in the optical axis direction is proportional to the frictional force (contact area) generated between the spherical body 17 and the side surface of the holder 15. Therefore, a configuration corresponding to the volume of the magnetic circuit portion of the actuator and the amount of current applied to the magnetic circuit can be realized by appropriately setting the contact area between the spherical body 17 and the side surface of the holder 15.

  In addition, the present actuator preferably has a configuration in which the spherical bodies are separated so as to sandwich the holder 15 when viewed from the optical axis direction. With such a configuration, the contact surface between the spherical body 17 and the side surface of the holder 15 is arranged at a position symmetrical with respect to the optical axis (center axis) of the holder 15 and is supported in a direction perpendicular to the optical axis direction. There is no bias and more accurate movement support in the optical axis direction is possible.

  Further, the spherical body 17 in the present actuator is preferably made of a material that does not affect the arrangement in a strong magnetic field and does not affect the magnetic flux distribution by the magnetic circuit, that is, a nonmagnetic material. Examples of the material of the spherical body 17 include ceramic, brass, glass, nonmagnetic stainless steel, and the like.

  An example of the number and arrangement of the spherical bodies 17 in this actuator is shown in FIGS. As shown in FIG. 3, the spherical body 17 is disposed in the gap between the base 18 and the holder 15, on which the yoke 13 is fixed on the object side. Three spherical bodies 17 are arranged, and as shown in FIG. 1, the holders 15 are arranged between the three spherical bodies 17 in the optical axis direction. That is, each of the three spherical bodies 17 is arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction (the figure formed by connecting the three spherical bodies 17 is an equilateral triangle. ing).

  The spherical body 17 is also disposed in the gap between the upper guide 9 and the holder 15. Similarly to the arrangement of the spherical bodies 17 in the gap between the base 18 and the holder 15, the three spherical bodies 17 are each arranged at a position of approximately 120 ° from the center of the holder 15 in the optical axis direction.

  Furthermore, the recessed part 15a is formed in the position which opposes the upper guide 9 and the base 18 in the holder 15 side surface, respectively. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15a and the inner wall of the insertion groove 9a of the upper guide 9. Similarly, the spherical body 17 is accommodated in a space formed by the inner wall of the recessed portion 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, the holder 15 side surface, the spherical body 17, and Will be more reliable. In addition, the actuator can be miniaturized.

  In this actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner walls of the insertion grooves 9a and 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion grooves 9a and 18a are in contact with each other, a frictional force is generated between them, and there is a possibility that the movement of the holder 15 in the optical axis direction is hindered. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the optical axis direction within the insertion grooves 9a and 18a.

  In the present actuator, the leaf spring 11 is disposed on the object side of the holder 15. The leaf spring 11 is supported and fixed by the upper guide 9. The leaf spring 11 is in contact with the object-side surface of the holder 15 that moves in the optical axis direction. The leaf spring 11 applies a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. That is, the leaf spring 11 generates an elastic force proportional to the amount of movement of the holder 15 that moves in the optical axis direction. In this actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the position of the holder 15 and the current value applied to the coil 14 have a proportional relationship, and this proportional relationship is the same as that of the conventional actuator. Therefore, according to the present actuator, it is not necessary to perform special position control (for example, a separate position sensor) different from the conventional one due to the configuration in which the spherical body 17 is arranged. That is, in this actuator, the position control of the holder 15 can be performed in the same manner as the position control of the holder adopted in the conventional actuator. Therefore, it is possible to reduce the cost and size of the imaging device.

  As described above, in the present actuator, the position of the holder 15 is held by the balance between the thrust generated in the holder 15 by electromagnetic induction and the elastic force generated in the leaf spring 11. Therefore, the shape of the leaf spring 11 changes according to the focal position of the optical member 16 (specifically, the lens) held by the holder 15. That is, in this actuator, the position of the optical member 16 is set according to the position of the object to be imaged by the imaging device. Here, as an example, when the object to be imaged is relatively far from the actuator, the optical member 16 is configured to move to the optical axis direction image plane side (so-called Inf state; infinity state). On the other hand, when the object to be imaged is relatively close to the actuator, the optical member 16 is configured to move toward the object side in the optical axis direction (so-called macro state; close-up photographing state). The configuration shown in FIG. 3 shows, as an example, the shape change of the leaf spring 11 when the optical member 16 changes between the Inf state and the macro state.

  The leaf spring 11 shown in FIG. 3 is a deformation when changing only the leaf spring 11 from the state fixed to the holder 15 to confirm the change of the leaf spring 11 in this actuator. is there.

  Note that which position of the optical member 16 is to be in the Inf state or the macro state is appropriately determined according to the optical design of the actuator.

  Further, the leaf spring 11 may be in contact with the object-side surface of the holder 15 and apply a preload proportional to the amount of movement (displacement) of the holder 15 in the optical axis direction. In the present actuator, since the holder 15 is supported by the spherical body 17, it is not necessary to have a configuration in which the holder 15 is fixedly supported by the leaf spring 11 as in the conventional actuator. Therefore, the leaf spring 11 may be slidably in contact with the holder 15 that moves in the optical axis direction (the contact between the holder 15 and the leaf spring 11 as the holder 15 moves in the optical axis direction toward the object side). Part will fluctuate). In such a case, compared to a configuration in which the holder 15 is fixedly supported by the leaf spring 11, plastic deformation of the leaf spring 11 due to the vibration of the holder 15 when the imaging device for portable electronic device is dropped is further reduced.

  This actuator has the following effects because the holder 15 is held in contact with the spherical body 17. That is, this actuator has an effect of reducing the vibration amplitude of the holder 15 and shortening the vibration convergence time as compared with the conventional actuator.

  FIG. 4 is a graph showing the behavior (current-displacement characteristics) of a holder in a conventional actuator. FIG. 5 is a graph showing the behavior (current-displacement characteristics) of the holder in this actuator. The graphs of FIGS. 4 and 5 show the behavior of the holder when current steps of 10 mA (current steps of 30 mA, 40 mA,..., 80 mA) are applied to the magnetic circuit of the actuator. The horizontal axis of the graph is time, and the timing and application time when the current of each step of the current step is applied can be known. The vertical axis of the graph indicates the displacement of the holder in the optical axis direction when the current of each step of the current step is applied. 4 and 5 that the holder vibrates in the optical axis direction when a current of each step of the current step is applied to the actuator.

  In a conventional actuator, when a current step is applied, the holder vibrates, and it takes time for the vibration to converge. In the graph shown in FIG. 4, when a current step of 10 mA was applied, the vibration amplitude of the holder was 30 μm, and the vibration convergence time for the vibration amplitude to converge was about 90 ms. That is, in the conventional actuator, about 90 ms is required to converge the vibration in the optical axis direction of the holder.

  On the other hand, since this holder is held in a state where the holder 15 is in contact with the spherical body 17, the vibration of the holder seen in the conventional actuator can be suppressed and the vibration convergence time can be shortened. In the graph shown in FIG. 5, the vibration amplitude of the holder is 16 μm, and the vibration convergence time for the vibration amplitude to converge is about 15 ms. In this actuator, compared with the conventional actuator, the vibration convergence time is about 1/6, and the vibration amplitude is also about 1/2.

  Therefore, the present actuator can shorten the time required for the holder position to be stabilized as compared with the conventional actuator. Such shortening of the holder position stabilization time contributes to, for example, speeding up the autofocus operation.

  Further, the present actuator is not limited to the configuration in which only the spherical body 17 supports the movement of the holder 15 in the optical axis direction. A configuration in which movement of the holder 15 in the optical axis direction is supported by both the spherical body 17 and the leaf spring 11 may be employed. In other words, the holder 15 may be fixedly supported by the leaf spring 11. In the conventional actuator, two leaf springs 10 are necessary to fix and support the holder 15. On the other hand, since the spherical body 17 is used for supporting the movement of the holder 15 in the optical axis direction, only one leaf spring 11 for fixing and supporting the holder 15 is required. Therefore, even if the same spring constant is set for the leaf spring 11, the strength of the leaf spring 11 per unit increases as compared with a conventional actuator using two leaf springs. The resistance of the leaf spring 11 when the device is dropped can be increased. In this case, the spherical body 17 close to the object side to which the leaf spring 11 and the holder 15 are fixed may be omitted.

  This actuator can be expressed as having the following configuration. That is, an imaging element, an optical member that inputs a video signal to the imaging element, a holder that holds the optical member, a coil that is provided on the outer periphery of the holder, and a magnet that is provided around the coil In addition, in the actuator in which the magnetic body is fixed to the base that fixes the imaging device, the holder is connected to the gap between the holder and the base via a sphere made of a nonmagnetic material so that the holder can move in the optical axis direction. It can be expressed that it is a configured.

  Furthermore, this actuator can be expressed as a configuration in which a magnetic body having ferromagnetism is attached to the base, and a magnet is provided on one surface of the magnetic body.

(Modification 1)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 6 is a cross-sectional view showing the main configuration of the present actuator as the first modification. The configuration shown in FIGS. 1 to 3 is a configuration in which a cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, the present actuator may be configured not to include the yoke 13 as in the first modification shown in FIG.

  As shown in FIG. 6, the magnetic circuit in the actuator of the first modification includes a magnet 12 and a coil 14. The holder 15 that holds the optical member is fixed integrally with the coil 14 so as to be accommodated in the coil 14. A cylindrical magnet 12 is disposed so as to surround the outer periphery of the coil 14. And in the magnetic circuit of the actuator of the modification 1, the member arranged on the outermost periphery is the magnet 12.

(Modification 2)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 1 to 3 will be described. FIG. 7 is a cross-sectional view showing a main configuration of the actuator as the second modification. The configuration shown in FIGS. 1 to 3 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, the present actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 2 shown in FIG.

  As shown in FIG. 7, the magnetic circuit in the actuator of the second modification includes a magnet 12, a yoke 13, and a coil 14. And the magnet 12 is hold | maintained integrally with the holder 15 holding an optical member. The coil 14 is disposed around the magnet 12. That is, the coil 14 is disposed so as to accommodate the magnet 12 and the holder 15. The coil 14 is fixed to the inner wall of the yoke 13.

  In the actuator of the second modification, when a current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, and the optical axis direction is relative to the holder 15 that is integrally fixed to the magnet 12. The thrust is generated.

  Compared with the configuration shown in FIGS. 1 to 3, the actuator of Modification 2 does not need to provide a power supply wire in the holder 15 as a movable part, and thus the structure can be simplified. Play.

  Considering the configurations of the first and second modifications, the actuator can be expressed as having the following configuration. That is, an optical member that forms an image of an object to be imaged, and one of a coil and a magnet that are used to move the optical member in the optical axis direction, and a holder that holds the optical member And a support that supports the other of the coil and the magnet, and the holder and the support, and the holder can be moved in the optical axis direction relative to the support by rotating. It can be expressed as a configuration including a spherical body.

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, for convenience of explanation, members having the same functions as those described in Embodiment 1 are given the same numbers, and explanation thereof is omitted.

  8 and 9 show the configuration of the main part of the actuator of the present embodiment (hereinafter referred to as the present actuator), FIG. 8 is an exploded perspective view, and FIG. 9 is a cross-sectional view.

  In the actuator of the first embodiment, the spherical body 17 is arranged in the gap between the base 18 and the holder 15 and the gap between the upper guide 9 and the holder 15. On the other hand, as shown in FIGS. 8 and 9, the present actuator has a configuration in which the spherical body 17 is disposed only in the gap between the base 18 and the holder 15. A plurality of spherical bodies 17 are arranged in contact with the side surface of the holder 15. A plane perpendicular to the optical axis direction is formed by the individual spherical bodies 17. In other words, the individual spherical bodies 17 are arranged on the same plane perpendicular to the optical axis direction.

  The leaf spring 11 is fixed and supported by the upper guide 9. The upper guide 9 functions as an elastic member fixing portion that fixes and supports the leaf spring 11. Further, only one leaf spring 11 is disposed apart from the plane formed by the individual spherical bodies 17 in the optical axis direction. Therefore, the following effects can be obtained as compared with the conventional actuator in which the holder is fixedly supported by a pair (a plurality) of leaf springs.

  That is, in the conventional configuration, the spring constant necessary for supporting the holder in the optical axis direction is a spring constant synthesized by two leaf springs. Therefore, in the conventional configuration, the strength of the individual leaf springs is weakened to support the movement of the holder in the optical axis direction.

  On the other hand, this actuator has a configuration in which the holder 15 is supported by one leaf spring 11, and is not a configuration in which the holder is fixedly supported by a plurality of leaf springs as in the conventional configuration. Therefore, the spring constant necessary for supporting the holder 15 to move in the optical axis direction can be designed with the spring constant of one leaf spring 11. For this reason, compared with the conventional structure, the spring constant of the leaf | plate spring 11 can be designed largely, and intensity | strength can be enlarged. Even if the actuator is downsized, it is not necessary to reduce the spring constant of the leaf spring as in the prior art, and it is possible to realize an actuator with excellent impact resistance.

  Further, the spherical body 17 provided in the present actuator can be appropriately set according to the volume of the magnetic circuit portion, the amount of current applied to the magnetic circuit, and the like. For example, as for the number of the spherical bodies, it is sufficient that at least three spherical bodies are arranged on either the object side or the image plane side across the coil 14 on the side surface of the holder 15. A configuration in which two spherical bodies are arranged is not preferable because the position of the holder becomes unstable when the holder moves in the optical axis direction.

  Further, a recess 15 a is formed at a position facing the base 18 on the side surface of the holder 15. The spherical body 17 is accommodated in a space formed by the inner wall of the recess 15 a and the inner wall of the insertion groove 18 a of the base 18. Therefore, when the holder 15 moves in the optical axis direction, the spherical body 17 rotates in these spaces and is supported by the frictional force with the inner wall of the recess 15a. Thus, since the hollow part 15a is formed in the holder 15 side surface, when the holder 15 moves to an optical axis direction, the spherical body 17 does not leave | separate from the holder 15 side surface, the holder 15 side surface, the spherical body 17, and Will be more reliable. In addition, the actuator can be miniaturized. In addition, although it demonstrated as a structure which formed the hollow part here, considering the productivity more, it is good also as a structure which formed the hole part which can be easily inserted from an upper surface or a lower surface. In order to prevent the spherical body from being detached from the hole portion, a configuration may be adopted in which an inclination or the like is provided in the hole portion or a cover for closing the hole portion is provided.

  In the present actuator, the spherical body 17 is arranged so that the side surface of the holder 15 and the inner wall of the insertion groove 18a do not contact each other. In a state where the side surface of the holder 15 and the insertion groove 18a are in contact with each other, a frictional force is generated by sliding between the two, and this sliding frictional force is much larger than the frictional force due to rolling of the spherical body. For this reason, compared with the present actuator in which the spherical body 17 is arranged, there is a possibility that the movement of the holder 15 in the optical axis direction is hindered by 10 to several tens of times. In this sense, it can be said that the spherical body 17 in this actuator functions as a guide member that smoothly moves the holder 15 in the insertion groove 18a in the optical axis direction.

  In addition, the structure of the modification 1 and 2 of the said Embodiment 1 can be applied to this actuator. A specific modification thereof will be described below.

(Modification 3)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 10 is a cross-sectional view showing the main configuration of the actuator as the third modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the cylindrical magnet 12 is fixed to the inner wall of the yoke 13 with an adhesive. However, this actuator may be configured not to include the yoke 13 as in the third modification shown in FIG.

(Modification 4)
In the configuration of this actuator, a modified example of the configuration shown in FIGS. 8 and 9 will be described. FIG. 11 is a cross-sectional view showing the main configuration of the actuator as the fourth modification. The configuration shown in FIGS. 8 and 9 is a configuration in which the holder 15 is fixed integrally with the coil 14. However, this actuator may have a so-called moving magnet type configuration in which the holder 15 is fixed integrally with the magnet 12 as in Modification 4 shown in FIG.

  In addition, about this actuator, the structure by which the spherical body 17 was distribute | arranged only to the clearance gap between the base 18 and the holder 15 has been demonstrated. However, the present actuator is not limited to this configuration, and may be a configuration arranged in the gap between the upper guide 9 and the holder 15.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The actuator of the present invention and the imaging device equipped with the actuator can be applied to all devices such as a camera mounted on a portable electronic device, and the actuator can be made smaller, thinner, and improved in impact resistance. Become. In addition, the actuator of the present invention and the imaging device including the actuator are not limited to portable electronic devices, and can be applied to, for example, in-car cameras and other applications that have a large impact and other electronic devices.

It is a disassembled perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is a perspective view which shows the principal part structure of the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the actuator of one Embodiment of this invention. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the conventional actuator. It is a graph which shows the transient characteristic (current-displacement characteristic) of the holder in the actuator of one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIGS. It is a disassembled perspective view which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the actuator of the other form of implementation of this invention. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the other modification of the actuator of FIG.8 and FIG.9. It is sectional drawing which shows the principal part structure of the conventional actuator.

Explanation of symbols

9 Upper guide (support)
9a Insertion groove 10 Leaf spring 11 Leaf spring (elastic member)
12 Magnet 13 Yoke (magnetic material)
14 Coil 15 Holder 15a Recess 16 Optical member 17 Ball 18 Base (support)
18a Insertion groove 19 Image sensor

Claims (16)

An optical member that forms an image of an object to be imaged;
A holder for holding the optical member;
A magnetic circuit for moving the optical member in the optical axis direction;
An actuator comprising a support for supporting the magnetic circuit,
The magnetic circuit includes a coil and a magnet, one of the coil and the magnet is attached to the holder, and the other is supported by the support.
A spherical body is arranged in the gap between the holder and the support,
The actuator according to claim 1, wherein the spherical body is rotated by movement of the holder in the optical axis direction. The support is formed with an insertion groove through which the holder is inserted,
The actuator according to claim 1, wherein the spherical body is disposed so as to contact both the side surface of the holder and the inner wall surface of the insertion groove.   3. The actuator according to claim 1, wherein a plurality of the spherical bodies are arranged, and the spherical bodies are in a positional relationship such that the holders are sandwiched when viewed from the optical axis direction. .   The actuator according to claim 3, wherein the spherical bodies are arranged on the same plane perpendicular to the optical axis direction. A recess is formed on the side of the holder,
The actuator according to any one of claims 1 to 4, wherein a space capable of accommodating the spherical body is formed by an inner wall surface of the recess and the support.   An elastic member that contacts the object side surface of the holder that moves in the optical axis direction and that gives the holder an elastic force proportional to the amount of movement of the holder in the optical axis direction is provided. The actuator according to any one of claims 1 to 5.   The actuator according to claim 6, wherein the elastic member is slidably in contact with a holder that moves in the optical axis direction. A plurality of the spherical bodies are arranged, and each spherical body is arranged on the same plane perpendicular to the optical axis direction,
The actuator according to claim 6, wherein the elastic member is disposed so as to be separated from the plane in the optical axis direction. The support includes a first support that supports one end of the magnetic circuit in the optical axis direction, and a second support that supports the other end.
The spherical body is disposed in any one of a gap between the holder and the first support and a gap between the holder and the second support. The actuator according to any one of 8.   The actuator according to any one of claims 1 to 9, wherein the magnetic circuit further includes a magnetic body having ferromagnetism, and the magnetic body is attached to the support.   The actuator according to claim 10, wherein the magnetic circuit includes a coil provided on the outer periphery of the holder, the magnet disposed around the coil, and the magnetic body.   The actuator according to claim 10, wherein the magnetic circuit includes a magnet provided on an outer periphery of the holder, the coil disposed around the magnet, and the magnetic body.   The actuator according to any one of claims 1 to 12, wherein the spherical body is made of a nonmagnetic material. Two support bodies are provided with a magnet and a coil sandwiched in the optical axis direction,
The actuator according to claim 1, wherein a space for restricting movement of the coil in the optical axis direction is formed by the two support bodies and the magnet. The actuator according to any one of claims 1 to 14,
An imaging device comprising: an imaging device that converts an image formed by an optical member into an electrical signal.   An electronic apparatus comprising the imaging apparatus according to claim 15.

Images