JP2009044807A - Actuator, imaging apparatus, and imaging equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain size reduction and thinning with high generated thrust, and to obtain assembability. <P>SOLUTION: This actuator can improve the thrust generated in a coil 13, at size reduction, since the coil 13 is an air-core coil which shapes a polygonal form, and magnets 11 are arranged so that they have equal intervals with the sidewall of the coil 13 forming each side of the polygon. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an actuator, an imaging device, and an imaging 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.

  Further, as a method of supporting the holder that holds the 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.

  Further, a closed magnetic circuit configuration is often used as the configuration of the magnetic circuit. This closed magnetic circuit configuration has two yokes made of a ferromagnetic material. One of the two yokes is attached to the magnet, and the other is arranged at a position facing the surface opposite to the surface to which the yoke is attached with a predetermined distance. A coil is disposed in the gap between these two yokes.

In a conventional actuator, a cylindrical holder has been used. For this reason, the magnet of the magnetic circuit provided on the entire circumference of the holder is also a cylindrical (arc-shaped) magnet. However, arc-shaped magnets are difficult to process and are expensive. For example, Patent Document 1 discloses an autofocus actuator having a magnetic circuit configuration in which a flat magnet is attached to an inner wall surface of a yoke formed in a polygonal cylindrical shape for the purpose of cost reduction.
JP 2006-81387 A (published March 23, 2006)

  However, when the autofocus actuator disclosed in Patent Document 1 is downsized (projection area is reduced) and thinned (reduction in height in the optical axis direction), the thrust generated by the electromagnetic induction phenomenon is reduced. . Hereinafter, the above-described problem relating to the conventional actuator will be specifically described.

  FIG. 6 is a plan view showing a main configuration of a voice coil type actuator used for autofocus of a general portable electronic device. FIG. 7 is a cross-sectional view of the actuator shown in FIG.

  As shown in FIGS. 6 and 7, the conventional actuator employs a closed magnetic circuit type magnetic circuit in which a plate-shaped magnet 111 is used and a coil 113 is arranged in the gap between the magnet 111 and the opposing yoke 116. Yes. More specifically, the yoke 112 made of a ferromagnetic material has a polygonal cylindrical shape, and a flat plate-shaped magnet 111 is attached to the inner wall forming the polygon. Further, the yoke 112 and the magnet 111 are held by the base 110. In the example shown in FIGS. 6 and 7, the yoke 112 has an octagonal cylindrical shape. And the magnet 111 is attached to the eight plate-shaped magnets 111 corresponding to the side wall of the yoke 112 which forms each side of the octagon. Moreover, the yoke 112 is provided with the opposing yoke 116 so as to face the magnet 111 and to be separated from the magnet 111. A coil 113 is disposed in the gap between the opposing yoke 116 and the magnet 111. The coil 113 has a cylindrical shape, and an opposing yoke 116 is disposed inside the cylinder. The holder 114 that holds the optical member 115 is fixed inside the coil 114 and moves in the optical axis direction integrally with the coil 114. Although not shown in FIGS. 6 and 7, the holder 114 is fixed to two leaf springs that are spaced apart in the optical axis direction. The leaf spring is deformed according to the movement of the holder 114 in the optical axis direction, and supports the holder 114. Thereby, the holder 114 is held at a predetermined position in the optical axis direction. Specifically, it becomes possible to hold the holder 114 at a position in the optical axis direction determined when the focus of the imaging object is adjusted. In the actuator shown in FIGS. 6 and 7, when an electric current is applied to the coil 113, an electromagnetic induction phenomenon occurs between the magnet 111 and the coil 113, so that the holder 114 moves in the direction of the arrow (optical axis direction). .

  In the conventional actuator shown in FIGS. 6 and 7, since the flat magnet 111 is attached to the cylindrical coil 113, there arises a problem that the generated thrust is reduced. That is, as shown in FIG. 6, in the conventional actuator, the distance between the magnet 111 and the coil 113 differs depending on the position on the cylindrical side surface of the coil 113. For example, at the position A on the cylindrical side surface of the coil 113, the distance between the magnet 111 and the coil 113 is δ1, and at the position B is δ2.

  It is difficult to assemble the actuator by setting the clearance between the magnet 111 and the coil 113 to a value smaller than a value called an assembly limit value. That is, the assembly limit value is a value that becomes the lower limit of the clearance between the magnet 111 and the coil 113 when the actuator is reduced in size and thickness. For example, the assembly limit value is set to 0.1 mm to 0.15 mm. Regarding the clearance between the magnet 111 and the coil 113, even if the distance δ1 between the magnet 111 and the coil 113 at the position A is set to the assembly limit value, δ2> δ1, that is, the distance δ2 at the position B becomes larger than the assembly limit value. End up. As a result, at position B, there is a problem that the density of magnetic flux passing through the coil 113 is reduced and the generated thrust is reduced.

  Further, as a configuration of a conventional magnetic circuit of an actuator, a moving coil type closed magnetic circuit configuration is widely used. The moving coil system is a system in which the holder 114 holding the optical member 115 is fixed to the coil 113 and the coil 113 moves integrally with the holder 114. In order to reduce the size and thickness of such an actuator, it is necessary to dispose the opposing yoke 116 in a limited space such as a gap between the coil 113 and the holder 114 that holds the optical member 115. In the actuator in which the opposing yoke 116 is arranged as described above, the clearance δ3 between the holder 114 and the opposing yoke 116, the clearance δ4 between the opposing yoke 116 and the coil 113, and the clearance between the coil 113 and the magnet 112 are used. There arises a problem that each δ5 becomes small. In a small actuator having one side of the outer shape of about 20 mm to 5 mm, the assembly limit value that is the limit of actuator assembly is substantially the same. For this reason, as the outer shape of the actuator is reduced, the ratio of the clearances δ3 to δ5 to the internal dimensions of the actuator increases. Therefore, if the actuator is designed to be smaller and thinner, the number of turns of the coil 113 and the thickness of the magnet 111 cannot be increased. As a result, when an actuator having a moving coil type closed magnetic circuit configuration is reduced in size and thickness, there arises a problem that thrust generated by an electromagnetic induction phenomenon is reduced.

  In addition, when the actuator is designed close to the assembly limit, it is difficult to assemble the actuator, which may cause assembly failure. And it leads to a decrease in yield due to an assembly failure and an increase in cost resulting therefrom.

  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 imaging device that are excellent in assemblability and can be reduced in size and thickness with high generated thrust. It is in.

  In order to solve the above problems, an actuator of the present invention includes an optical member, a holder for holding the optical member, a coil provided on the outer periphery of the holder, a magnet and a magnetic body disposed around the coil, And an actuator in which the holder is moved in the optical axis direction by a current applied to the coil, the coil being an air-core coil forming a polygonal shape. The magnets are arranged so as to be equidistant from the side walls of the coils forming the sides of the polygonal shape.

  According to the above configuration, the coil is an air-core coil that forms a polygonal shape, and the magnet is arranged so as to be equidistant from the side wall of the coil that forms each side of the polygonal shape. The clearance between the coil side wall and the magnet side wall is kept constant.

  With conventional actuators, the distance between the magnet and the coil differs depending on the position on the coil side, so even if the actuator is downsized, it is not possible to set the assembly limit value to the minimum distance between the magnet and the coil. Met.

  Therefore, in the conventional actuator, even if the assembly limit value is set to the minimum value of the distance between the magnet and the coil, the density of the magnetic flux passing through the coil differs depending on the position of the coil side surface. It had a problem that it was not possible to plan.

  On the other hand, in the above configuration, the clearance between the coil side wall and the magnet side wall is kept constant. Therefore, the magnetic flux passing through the coil can be reduced by setting the assembly limit value to the clearance when the actuator is downsized. The magnetic flux density inside the coil can be improved by making the density of the coil constant. As a result, according to the above configuration, it is possible to realize a higher generated thrust as compared with the conventional actuator.

  Further, according to the above configuration, in order to realize a high thrust generated when the actuator is downsized, it is only necessary to manage the clearance between the coil side wall and the magnet side wall, so that the assembly of the actuator is facilitated.

  Therefore, according to the above configuration, it is possible to provide an actuator that is excellent in assemblability and can be reduced in size and thickness with high generated thrust.

  In the actuator of the present invention, the magnetic body has a polygonal cylindrical shape, and the side walls forming the sides of the polygon in the magnetic body are provided so as to be parallel to the side walls of the coil. It is preferable.

  According to said structure, since the side wall which forms each side of the said polygon in a magnetic body is provided so that it may become parallel to the side wall of the said coil, the improvement of a generated thrust can be aimed at further.

  In the actuator of the present invention, it is preferable that the magnetic body is disposed only on the outer periphery of the coil, and the magnet is disposed on a surface of the magnetic body facing the coil.

  The above configuration includes a magnetic circuit having a so-called open magnetic circuit configuration in which the magnetic body is disposed only on the outer periphery of the coil, and the magnet is disposed on a surface of the magnetic body facing the coil. It is a configuration.

  In the conventional actuator, since the magnetic circuit has a closed magnetic circuit configuration provided with a counter yoke, it is necessary to manage three clearances including the clearance between the counter yoke and the magnet when assembling the actuator.

  On the other hand, according to the above configuration, since the magnetic circuit has an open magnetic path configuration, it is only necessary to manage only the clearance between the coil side wall and the yoke side wall when assembling the actuator. As a result, the actuator can be easily assembled.

  Moreover, the space provided with the opposing yoke in the conventional actuator can be used effectively. For example, it is possible to improve the thrust by increasing the number of turns of the coil.

  In the actuator of the present invention, it is preferable that the holder is arranged so that a gap is formed between the holder and the coil.

  Thereby, the heat of the coil generated at the time of energization can be efficiently radiated. Furthermore, since the heat of the coil is hardly transmitted to the holder, thermal deformation of the holder and the optical member held inside the holder can be reduced.

  In the actuator of the present invention, it is preferable that a resin material is filled in a gap formed by the holder and the coil.

  As a result, the holder and the coil can be firmly fixed, and the heat of the coil can be prevented from being directly transmitted to the holder. Moreover, in the imaging apparatus provided with the actuator of the present invention, it is possible to prevent the coil and the holder from being damaged when the imaging apparatus is dropped.

  In the actuator of the present invention, it is preferable that the holder has a cylindrical shape, and a wall surface of the holder forming the cylindrical shape is inscribed in a side wall of the coil.

  In said structure, the contact location of a coil and a holder becomes only the said inscribed location, and the location where the coil and the holder were separated exists. For example, a gap is formed by the side wall of the coil and the holder at the polygonal bent portion of the coil. For this reason, the heat of the coil generated during energization can be efficiently radiated.

  In the actuator of the present invention, the holder is parallel to the side wall of the coil and has a wall surface in contact with the side wall, the corner portion formed by the wall surface of the holder and the corner portion formed by the side surface of the coil. It is preferable that a gap is formed between the two.

  According to said structure, the said holder is parallel to the side wall of the said coil, has a wall surface which contacted this side wall, and the angle | corner formed by the corner | angular part formed by the wall surface of a holder, and the side surface of the said coil Since the air gap is formed between the coil and the coil, the heat of the coil generated during energization can be efficiently radiated.

  In the actuator according to the aspect of the invention, it is preferable that the holder includes a structure projecting toward the coil on an outer periphery thereof, and the structure is in contact with a polygonal apex formed by the side wall of the coil. .

  Thereby, the air-core coil which makes the polygonal shape which can accommodate a holder can be formed in the case of an actuator assembly. That is, an air core coil having a polygonal shape can be easily formed by winding the copper wire constituting the coil with the tip portion in the direction in which the structure projects as a fulcrum.

  In the actuator of the present invention, the holder includes a structure projecting toward the coil on an outer periphery thereof, and the holder is in contact with the coil only at a projecting tip portion from which the structure projects. Is preferred.

  According to said structure, the said holder is contact | abutted with the said coil only in the protrusion front-end | tip part from which the said structure protrudes, and the space | gap is formed with the holder and the coil except this contact part. Therefore, the heat of the coil generated during energization can be efficiently radiated.

  In the actuator of the present invention, the magnetic body has a polygonal cylindrical shape, and the magnet has a flat plate shape having the same size as a side wall forming each side of the polygon in the magnetic body. preferable.

  By using a plate-shaped magnet that is relatively inexpensive, it is possible to reduce the cost of the actuator.

  In the actuator according to the present invention, the coil is preferably an air-core coil that forms a regular octagonal shape.

  This makes it possible to secure a region (space) for mounting the optical member when the actuator is downsized.

  In the actuator of the present invention, it is preferable that the magnetic body has a regular octagonal cylindrical shape.

  When the magnetic body is a regular octagonal cylinder, impact resistance can be improved by using the side wall of the magnetic body forming the regular octagon as an actuator side wall.

  In order to solve the above-described problems, an imaging device according to the present invention is an imaging device including the above-described actuator, and the optical member is for imaging an object to be imaged. Yes.

  According to the above configuration, it is possible to provide an imaging apparatus that is excellent in assemblability and can be reduced in size and thickness with high generated thrust.

  In order to solve the above-described problems, an imaging apparatus according to the present invention includes the imaging apparatus and an imaging element that converts an image formed by an optical member into an electrical signal.

  According to the above configuration, it is possible to provide an imaging device that is excellent in assemblability and can be reduced in size and thickness with high generated thrust.

  As described above, in the actuator of the present invention, the coil is an air-core coil that forms a polygonal shape, and the magnet is equidistant from the side wall of the coil that forms each side of the polygonal shape. It is the structure arranged.

  Further, as described above, the imaging apparatus of the present invention has a configuration in which the optical member is for imaging an object to be imaged.

  In addition, as described above, the imaging apparatus of the present invention has a configuration including the imaging device and an imaging element that converts an image formed by the optical member into an electrical signal.

  Therefore, by setting the assembly limit value to clearance when downsizing the actuator, the density of the magnetic flux passing through the coil can be made constant and the magnetic flux density inside the coil can be improved, and high thrust generated can do. Further, since only the clearance between the coil side wall and the magnet side wall needs to be managed, the assembly of the actuator is facilitated.

  Therefore, it is excellent in assemblability and can be reduced in size and thickness with high generated thrust.

  Embodiments according to the present invention will be described with reference to FIGS. In the following description, the same members and components are denoted by the same reference numerals. The names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(Definition of terms)
Definitions of terms used in this specification will be described.

  In this specification, the “optical axis direction” is light from a subject incident on the optical lens and is parallel to the central axis of the light (a direction parallel to a line segment connecting the optical member and the subject). Means.

  Further, in the present specification, when describing the structure of each component, a surface and a part close to the subject are described as an “object side” surface and a part, and a surface and a part located opposite to the object side are referred to as an “image”. It is described as “surface side” surface and part.

  An actuator according to an embodiment of the present invention (hereinafter referred to as the present actuator) will be described below with reference to FIGS. FIG. 1 is a plan view showing a configuration when the actuator is observed from the object side. FIG. 2 is a perspective view showing the appearance of the actuator.

  As shown in FIGS. 1 and 2, the actuator includes a base 10, a magnet 11, a yoke 12, a coil 13, and a holder 14 that holds an optical member 15.

  This actuator is used for autofocusing of an imaging device mounted on a mobile electronic device such as a mobile phone. That is, this actuator forms an image of a subject to be imaged by the imaging device by the optical member 15. Then, the image formed by the optical member 15 is converted into an electric signal by the image sensor 20.

  The yoke 12 has an octagonal cylindrical shape. The holder 14 is disposed so as to be accommodated in the cylindrical shape of the yoke 12. That is, the yoke 12 is arranged around the holder 14. A flat plate-like magnet 11 is fixed to each side wall (hereinafter simply referred to as a side wall of the yoke 12) of the octagonal side of the yoke 12 by an adhesive. Therefore, when this actuator is observed from the object side, the figure formed by the flat magnet 11 is an octagon. The holder 14 that holds the optical member 15 is fixed integrally with the coil 13 so as to be accommodated in the coil 13.

  In the present actuator, the magnet 11, the yoke 12, and the coil 13 constitute a magnetic circuit. That is, when a current is applied to the coil 13, an electromagnetic induction phenomenon occurs between the magnet 11 and the coil 13. Due to this electromagnetic induction phenomenon, thrust in the optical axis direction is generated with respect to the holder 14 that is integrally fixed to the coil 13. The holder 14 moves in the optical axis direction by this thrust. Further, the thrust generated in the holder 14 is proportional to the amount of current applied to the coil 13.

  Although not shown in FIGS. 1 and 2, the actuator includes a parallel leaf spring that applies a preload proportional to the amount of movement (displacement) of the holder 14 in the optical axis direction. The parallel leaf springs are fixed to the object side surface and the image surface side surface of the holder 14.

  Next, the configuration of the magnetic circuit in this actuator will be further described in detail. As shown in FIG. 1, in this actuator, the coil 13 is an air-core coil having an octagonal shape. A side wall (hereinafter simply referred to as a side wall of the coil 13) that forms each side of the octagonal shape in the coil 13 and a side wall of the yoke 12 are disposed so as to face each other. In this actuator, the clearance (interval) δ6 between the side wall of the coil 13 and the side wall of the magnet 11 is kept substantially constant.

  In the conventional actuator, since the coil is an air-core coil having a circular shape, the distance between the magnet and the coil differs depending on the position on the coil side surface. For this reason, even if the actuator is downsized, it is a limit to set the assembly limit value to the minimum value of the distance between the magnet and the coil.

  In general, the density of magnetic flux passing through a coil is proportional to the distance between the magnet and the coil. That is, the closer the distance to the magnet is, the higher the magnetic flux density is, so the generated thrust is larger, and the farther away from the magnet is, the more the magnetic field lines are diffused and the magnetic flux density is lower, so the generated thrust is smaller. Therefore, in the conventional actuator, even if the assembly limit value is set to the minimum value of the distance between the magnet and the coil, the density of the magnetic flux passing through the coil differs depending on the position of the coil side surface. I can't plan. In addition, the effective line length of the coil through which the magnetic flux substantially passes is reduced.

  On the other hand, in the present actuator, the clearance δ6 between the side wall of the coil 13 and the side wall of the yoke 12 is kept substantially constant. Therefore, when the actuator is downsized, the assembly limit value is set to the clearance δ6, thereby passing the coil. The density of the magnetic flux to be generated can be made constant, and the magnetic flux density inside the coil can be improved.

  That is, even if the conventional actuator and the present actuator are set to the same assembly limit value for the distance between the magnet and the coil, the present actuator has a higher density of magnetic flux passing through the coil than the conventional actuator. And this actuator becomes large in the thrust which generate | occur | produces in a coil rather than the conventional actuator.

  Table 1 shows the results of comparing the generated thrusts of the coil 13 of the present actuator (air-core coil having an octagonal shape) and the coil 113 of the conventional actuator (air-core coil having a circular shape).

  Note that the number of turns of the coil, the magnet thickness, and the clearance between the coil and the magnet are the same in the conventional actuator and the present actuator. Specifically, in both the conventional actuator and the present actuator, the number of turns of the coil is set to 164T, the magnet thickness is set to 0.4 mm, and the clearance between the magnet and the coil is set to 0.15 mm. In Table 1, the generated thrust generated in the coil of the conventional actuator is 100%.

  As shown in Table 1, the present actuator including the air-core coil (coil 13) having an octagonal shape is more coiled than the conventional actuator having the air-core coil (coil 113) having a circular shape. It can be seen that the thrust generated is improved by 15%.

  Even if the number of turns of the coil, the magnet thickness, and the clearance between the coil and the magnet are set to the same conditions in the conventional actuator and this actuator, this actuator generates a thrust generated in the coil more than the conventional actuator. It can be seen that is increasing.

  Further, as shown in FIG. 1, in this actuator, the holder 14 that holds the optical member 15 has a cylindrical shape. The cylindrical holder 14 is inscribed in the inner wall surface forming the octagonal shape of the coil 13. In such a case, the contact location between the coil 13 and the holder 14 is only the location surrounded by the broken line shown in FIG. 1, and there is a location where the coil 13 and the holder 14 are separated from each other. For example, a gap is formed by the side wall of the coil 13 and the holder 14 at the bent portion of the coil 13. For this reason, the heat | fever of the coil 13 which generate | occur | produces at the time of electricity supply can be thermally radiated efficiently. Furthermore, since the heat of the coil 13 is difficult to be transmitted to the holder 14, thermal deformation of the holder 14 and the optical member 15 held inside the holder 14 can be reduced. As a result, it is possible to prevent image quality degradation due to heat of the camera module. In particular, the present actuator is effective when the material constituting the optical member 15 is a plastic material.

  The shape of the holder 14 is not limited to a cylindrical shape. The shape of the holder 14 may be any shape that can be accommodated inside the coil 13 and can form a gap between the side wall of the coil 13 and the holder 14. An example is the configuration shown in FIG. FIG. 3 is a plan view showing another shape of the holder in the actuator.

  As shown in FIG. 3, the shape of the holder 14 is a substantially octagonal cylindrical shape. The holder 14 has a side surface 14a that is parallel to the side wall of the coil 13 and is in contact with the side wall (in the top view, the portion where the coil 13 and the holder 14 are in contact is a straight line). ) And the corner | angular part 14r formed of the two side surfaces 14a has an arc-shaped side surface. According to the configuration shown in FIG. 3, since a gap is formed between the arc-shaped side surface of the corner portion 14r and the corner portion 14r of the coil 14, the heat of the coil 13 generated during energization is efficiently radiated. be able to.

  The side surface of the corner portion 14r is not limited to the arc-shaped side surface, and may be any side surface that can form a gap with the corner portion 14r of the coil 14. For example, it may be a flat surface.

  In the present actuator, the yoke 12 is disposed only on the outer periphery of the coil 13, and the magnet 11 is fixed to the surface of the side wall of the yoke 12 that faces the coil 13. That is, the magnetic circuit in this actuator has a so-called open magnetic path configuration in which no opposing yoke is disposed between the holder 14 and the magnet 11.

  In the conventional actuator shown in FIGS. 6 and 7, the magnetic circuit has a closed magnetic circuit configuration including the opposing yoke 116. Therefore, when assembling the actuator, it is necessary to manage three clearances including the clearance between the opposing yoke 116 and the magnet 113.

  On the other hand, in the present actuator, since the magnetic circuit has an open magnetic path configuration as described above, only the clearance δ6 between the side wall of the coil 13 and the side wall of the yoke 12 needs to be managed when assembling the actuator. Therefore, the actuator assembly becomes easy.

  Further, in comparison with a conventional actuator in which the magnetic circuit has a closed magnetic circuit configuration, this actuator can effectively use the space provided with the opposing yoke. For example, the thrust generated in the coil 13 can be improved by increasing the number of turns of the coil 13 and effectively using the space provided with the opposing yoke.

  As described above, when the number of turns of the coil 13 is increased to effectively use the space provided with the opposing yoke, the shape of the holder 14 is such that a gap can be formed between the side wall of the coil 13 and the holder 14. It is desirable to be.

  In general, when the magnetic circuit has an open magnetic circuit configuration, the amount of decrease in the density of the magnetic flux passing through the coil tends to increase in proportion to the distance between the coil and the magnet, compared to the closed magnetic circuit configuration. is there. For this reason, compared with the conventional actuator provided with the closed magnetic circuit structure as a magnetic circuit, generated thrust becomes easy to become small. Therefore, in an actuator having an open magnetic path as a magnetic circuit, it is conceivable to increase the number of turns of the coil in order to maintain the generated thrust. At this time, since the electric resistance of the coil is increased, the amount of heat generated from the coil when the actuator is driven may be larger than that in the configuration including the closed magnetic circuit as the magnetic circuit.

  In the magnetic circuit of this actuator, as described above, since the number of places where the coil 13 and the holder 14 are in direct contact with each other is reduced, the heat generated from the coil 13 can be efficiently radiated. Therefore, as compared with the conventional actuator, this actuator has a configuration that is advantageous for an increase in coil heat generation caused by an increase in the number of coil turns.

  Furthermore, this makes it possible to suppress an increase in the temperature of the holder 14 in contact with the coil 13. As a result, the temperature rise of the optical member 15 held inside the holder 14 can be suppressed, and the deformation and internal stress of the holder 14 and the optical member 15 can be reduced. Furthermore, it is possible to realize an actuator that can suppress degradation of optical characteristics. In particular, in the configuration provided with a plastic lens used for a camera in recent years as the optical member 15, a change in optical characteristics due to a temperature change is large. By applying the magnetic circuit of the present actuator to a configuration including such a plastic lens, it is possible to efficiently suppress changes in optical characteristics due to temperature changes.

  The actuator may include a cured product of a resin material that fills a gap formed by the side wall of the coil 13 and the side wall of the holder 14. Thereby, the adhesive strength between the coil 13 and the holder 14 increases. And in the imaging device provided with this actuator, it becomes possible to prevent the coil 13 and the holder 14 from being damaged when the imaging device is dropped. Note that the resin material filling the voids is preferably a resin having low heat transfer and high heat resistance. Examples of the resin material include an epoxy resin and an ultraviolet curable resin.

(Modification 1)
A modification of the actuator shown in FIGS. 1 and 2 will be described below with reference to FIG. FIG. 4 is a plan view showing a configuration when the actuator as the first modification is observed from the object side. In addition, in order to avoid the complexity of drawing, the base 10, the magnet 11, and the yoke 12 are abbreviate | omitted in FIG.

  The actuator of Modification 1 is different from the configuration shown in FIGS. 1 and 2 in that a structure 17 is provided on the outer peripheral surface of the holder 14. The structure 17 protrudes from the outer peripheral surface of the holder 14 to the coil 13, and is in contact with a bent portion where a side wall forming an octagon in the coil 13 is bent. In other words, when the actuator is observed from the object side, the structures 17 extend radially about the axis O of the holder 15. The octagonal apex 13a on the side wall of the coil 13 and the tip 17a from which the structure 17 protrudes (hereinafter referred to as a protruding tip) 17a abuts (contacts).

  By providing this structure 17, an air-core coil (coil 13) having an octagonal shape that can accommodate the holder 14 can be formed during actuator assembly. That is, an air-core coil having an octagonal shape can be easily formed by winding the copper wire constituting the coil 13 with the protruding tip 17a of the structure 17 as a fulcrum.

(Modification 2)
Another modification of the actuator shown in FIG. 4 will be described below with reference to FIG. FIG. 5 is a plan view showing a configuration when the actuator as the second modification is observed from the object side. In addition, in order to avoid the complexity of drawing, the base 10, the magnet 11, and the yoke 12 are abbreviate | omitted in FIG.

  In the actuator of the first modification, the holder 14 has a cylindrical shape. On the other hand, in the actuator of Modification 2, the shape of the holder 14 is a cylindrical shape that forms an octagonal shape. The outer wall surface 14 a forming each side of the octagon is formed to be parallel to the side wall of the coil 13. That is, in the actuator according to the second modification, the contact portion of the holder 14 with the coil 13 is only the protruding tip portion 17 a of the structure 17. A gap is formed by the side wall of the coil 13, the structure 17, and the outer wall surface 14a.

  Compared with the first modification, the actuator of the second modification has fewer contact points between the coil 13 and the holder 14 and more gaps between the coil 13 and the holder 14. For this reason, the actuator of the modification 2 can further reduce the influence of the heat generated from the coil 13 being transmitted to the holder 14 as compared with the modification 1.

  In this actuator, the yoke 12 has an octagonal cylindrical shape. However, the yoke 12 is not particularly limited as long as it has a polygonal cylindrical shape. For example, the yoke 12 may have a hexagonal or dodecagonal cylindrical shape. In particular, the yoke 12 is preferably a regular octagonal cylinder. When the yoke 12 has a regular octagonal cylindrical shape, impact resistance can be improved by using the side wall of the yoke 12 forming the regular octagon as an actuator side wall.

  Further, the coil 13 is not particularly limited as long as it is an air-core coil that forms a polygon having sides parallel to the side wall of the yoke 12. In particular, the coil 13 is preferably an air-core coil that forms a regular octagon. Thereby, when the actuator is downsized, it is possible to secure a region (space) for mounting the optical member 15.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

(Other configurations)
In addition, this invention is realizable also with the following structures.

(First configuration)
An optical member, a holder for holding the optical member, a coil provided on the outer periphery of the holder, and a magnetic circuit composed of a magnet and a magnetic body around the coil. The holder is moved in the optical axis direction by an electric current applied to the coil. An actuator that moves to a position where the magnetic body and the coil have a polygonal shape.

(Second configuration)
The actuator according to the first configuration, wherein the magnetic body is disposed on the outer periphery of the polygonal coil, and the magnet is fixed to the inner surface of the magnetic body at a position facing the coil.

(Third configuration)
The actuator which concerns on the 1st or 2nd structure which provided the holder inscribed in the coil which has a polygonal shape.

(Fourth configuration)
The structure provided around the holder is formed at a position corresponding to a gap formed by a coil having a polygonal shape and a holder provided in contact with the coil, and the tip of the structure has a polygonal shape. The actuator which concerns on the 3rd structure which contact | connects each vertex of the coil which has.

(Fifth configuration)
An actuator according to a fourth configuration,
The actuator which has a clearance gap between the polygonal shape which connects the front-end | tip part of the structure provided in the periphery of the holder, and the outer periphery of a holder.

(Sixth configuration)
The actuator which concerns on any one of the 1st-5th structure by which resin is filled into the clearance gap formed of the coil which has a polygonal shape, and the holder provided inscribed in the coil.

(Seventh configuration)
The magnet according to any one of the first to sixth configurations, wherein the magnet is a flat plate having the same size as the flat portion of the polygonal magnetic body.

(Eighth configuration)
The actuator according to any one of the first to seventh configurations, wherein the magnetic body and the coil have a regular octagonal shape.

(Ninth configuration)
An imaging apparatus equipped with an actuator according to any one of the first to eighth configurations having an optical member that forms an image of an object to be imaged.

(Tenth configuration)
An imaging apparatus comprising an imaging apparatus according to a ninth configuration.

  The actuator of the present invention and the imaging device using the actuator can be applied to all devices such as a camera mounted on a portable device, and it is possible to achieve both downsizing and assembling of the actuator.

It is a top view which shows the structure at the time of observing the actuator of one Embodiment of this invention from the object side. It is a perspective view which shows the external appearance of the actuator of FIG. It is a top view which shows another shape of the holder in the actuator of this invention. It is a top view which shows the structure at the time of observing this actuator as the modification 1 from the object side. It is a top view which shows the structure at the time of observing this actuator as the modification 2 from the object side. It is a top view which shows the principal part structure of the voice coil type actuator used for the autofocus of a general portable electronic device. FIG. 7 is a cross-sectional view of the actuator shown in FIG. 6.

Explanation of symbols

11 Magnet 12 Yoke (Magnetic material)
13 Coil 14 Holder 15 Optical member 17 Structure

Claims (14)

An optical member;
A holder for holding the optical member;
A magnetic circuit comprising a coil provided on the outer periphery of the holder and a magnet and a magnetic body disposed around the coil, and the holder is moved in the optical axis direction by an electric current applied to the coil. An actuator,
The coil is an air-core coil that forms a polygonal shape,
The actuator, wherein the magnet is arranged so as to be equidistant from a side wall of a coil forming each side of the polygonal shape. The magnetic body has a polygonal cylindrical shape,
2. The actuator according to claim 1, wherein a side wall forming each side of the polygon in the magnetic body is provided so as to be parallel to the side wall of the coil. The magnetic body is disposed only on the outer periphery of the coil,
The actuator according to claim 1, wherein the magnet is disposed on a surface of the magnetic body facing the coil.   The actuator according to any one of claims 1 to 3, wherein the holder is arranged so that a gap is formed between the holder and the coil.   The actuator according to claim 4, wherein a resin material is filled in a gap formed by the holder and the coil. The holder has a cylindrical shape,
6. The actuator according to claim 4, wherein a wall surface of the holder that forms a cylindrical shape is inscribed in a side wall of the coil. The holder is parallel to the side wall of the coil and has a wall surface in contact with the side wall;
The actuator according to claim 4 or 5, wherein a gap is formed between a corner formed by a wall surface of the holder and a corner formed by a side surface of the coil. The holder includes a structure projecting toward the coil on the outer periphery thereof,
The actuator according to claim 1, wherein the structure is in contact with a vertex of a polygon formed by a side wall of the coil. The holder includes a structure projecting toward the coil on the outer periphery thereof,
The actuator according to any one of claims 1 to 7, wherein the holder is in contact with the coil only at a protruding tip from which the structure protrudes. The magnetic body has a polygonal cylindrical shape,
The actuator according to any one of claims 1 to 9, wherein the magnet has a flat plate shape of the same size as a side wall forming each side of the polygon in the magnetic body.   The actuator according to any one of claims 1 to 10, wherein the coil is an air-core coil that forms a regular octagonal shape.   The actuator according to any one of claims 1 to 11, wherein the magnetic body has a regular octagonal cylindrical shape. An imaging apparatus comprising the actuator according to any one of claims 1 to 12,
An imaging apparatus, wherein the optical member is for imaging an object to be imaged. An imaging device according to claim 13,
An imaging device comprising: an imaging device that converts an image formed by an optical member into an electrical signal.

Images