JP2013085331A - Electromagnetic driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic driving device in which the driving magnet and driving coil are downsized, the device still has good linear motion and strong driving force.SOLUTION: The electromagnetic driving device comprises: a lens holder 12 that is a moving member; a case 13 that is a securing member for supporting the lens holder 12 so that it can move in a direction of the axis line of the holder 12; a driving coil 15 that is wound around the axis line of the lens holder 12; and a driving magnet 16 magnetized in a radiation direction of the axis line. The driving magnet 16 is arranged around the axis line of the lens holder 12. The driving coil 15 is arranged, in either of one and the other or both sides of the axis line of the driving magnet 16, coaxially with the driving magnet 16, and arranged across a void oppositely to the surface different from the magnetic surface of the driving magnet 16.

Description

  The present invention relates to an electromagnetic drive device used in, for example, an autofocus lens drive device and a linear actuator.

In recent years, in cameras mounted on mobile phones and the like, the number of pixels of an image sensor has been increased and the quality of captured images has been increasing. However, since the conventional fixed-focus camera module is defocused and cannot cope with the resolution of the high-pixel-number image sensor, a movable-focus camera module has been adopted. As a lens driving method in the movable focus camera module, an electromagnetic driving lens driving device 50 as shown in FIG. 18 is often used (for example, see Patent Document 1).
The lens driving device 50 is attached to a yoke 51 made of a magnetic material such as soft iron, a driving magnet 52 attached to the inner wall side of the yoke 51, a lens holder 54 that holds the lens 53 at the center position, and the lens holder 54. A driving coil 55, a case 56 on which the yoke 51 is mounted on the inner peripheral side, and front and rear leaf springs 57A and 57B for connecting the lens holder 54 and the case 56 are provided.

As the driving magnet 52, a cylindrical magnet that is magnetized in a radial direction with respect to the axis of the lens holder 54, or a magnet in which a plurality of magnets on an arc are arranged annularly on the inner wall side of the yoke 51 is used. .
The yoke 51 includes an outer part 51a disposed on the inner peripheral side of the case 56, an inner part 51b inserted on the inner peripheral side of the driving coil 55, and a connecting part 51c that connects the outer 51a and the inner part 51b. Is provided.
The driving coil 55 is disposed between the inner portion 51b of the yoke 51 and the driving magnet 52 with a gap therebetween. Since a radial magnetic field is applied to the drive coil 55 by the drive magnet 52 and the inner portion 51b of the yoke 51, when the drive coil 55 is energized, the Lorentz force toward the subject is applied to the drive coil 55. Thus, the lens holder 54 can be moved to a position balanced with the restoring force of the front and rear leaf springs 57A and 57B. Therefore, by controlling the current value supplied to the driving coil 55, the amount of movement of the lens holder 54 can be adjusted, and the position of the lens 53 can be moved to a predetermined position.

JP 2004-280031 A

On the other hand, the space that can be occupied by the camera module is steadily decreasing due to the increase in the volume occupied by electronic circuit components accompanying the downsizing and thinning of mobile phones and the increase in functionality. For this reason, the lens driving device is required to be further reduced in size, but the lens 53 is required to have a higher resolution in accordance with an increase in the number of pixels of a captured image. Therefore, improvement of lens performance is prioritized over miniaturization of lens diameter and lens thickness. From such a background, in the lens driving device, it is necessary to reduce the dimension, particularly the outer dimension OD in the width direction (see FIG. 18) while maintaining the lens dimension.
In the conventional lens driving device 50, in order to reduce the outer dimension OD and realize the miniaturization, it is necessary to reduce the dimensions of the components arranged in the space between the lens 53 and the outer dimension OD. Therefore, for example, as shown in FIG. 19, the driving magnet 52 is cut in accordance with the reduction of the outer dimension OD, and the outer edge 51a of the yoke 51 having a rectangular outer edge is arranged at the four corners. Alternatively, a method of securing the space by deleting the inner portion 51b of the yoke 51 can be considered.

However, when the driving magnets 52 are arranged at the four corners of the outer portion 51a of the yoke 51, the volume of the driving magnets 52 is reduced, the generated magnetic force is weakened, and the area facing the driving coil 55 is reduced. Since the utilization factor of the driving coil 55 decreases and the driving force decreases, there is a problem in that the driving force decreases.
Further, when the inner portion 51 b of the yoke 51 is omitted, it is difficult to effectively guide the magnetic flux from the driving magnet 52 in the direction intersecting the driving coil 55, which is sufficient for the driving coil 55. There is a problem in that the driving force is reduced because it is impossible to apply an amount of magnetic flux. Furthermore, the uniformity of the magnetic field is lost with the miniaturization of the magnet, resulting in a problem that the linearity of the drive sensitivity is deteriorated.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide an electromagnetic drive device that has excellent linearity of operation and a strong driving force even if the drive magnet and the drive coil are downsized. And

The invention according to claim 1 of the present application includes a columnar or cylindrical movable member, a fixed member that suspends and supports the movable member so as to be movable in the axial direction of the movable member, and a winding around the axis of the movable member. An electromagnetic drive device comprising: a drive coil configured to be driven; and a drive magnet magnetized in a radial direction with respect to the axis, wherein the drive magnet is disposed around the axis of the movable member, and the drive The driving coil is coaxial with the driving magnet on one side or both sides of one side in the axial direction of the driving magnet and the other side in the axial direction, and the magnetic pole of the driving magnet It is characterized by being arranged to face a surface different from the surface with a gap.
Here, assuming that the axial direction of the movable member is the + Z direction indicated by the arrow in FIG. 1, the driving coil is disposed on one or both of the + Z side and the −Z side of the driving magnet. The
In this way, by configuring the drive magnet and the drive coil along the axial direction of the movable member, the radial thickness of the drive magnet can be reduced even if the drive unit of the electromagnetic drive device is downsized. Since it can be ensured, a uniform and strong magnetic field can be applied to the drive coil. Therefore, it is possible to obtain an electromagnetic driving device that has excellent linearity of operation and has a strong driving force. Further, since the cross-sectional shape of the winding can be made wider in the radial direction, there is an advantage that the drive current can be reduced.

Invention of Claim 2 is the electromagnetic drive device of Claim 1, Comprising: From the inner peripheral side magnetic pole surface of the said drive magnet, one side of the axial direction of the said movable member, and the other side of the axial direction An inner magnetic yoke that is extended to one or both of them and is disposed to face the inner peripheral side of the driving coil with a gap, and from the outer peripheral side magnetic pole surface of the driving magnet to the axial direction of the movable member Any one of the outer magnetic yokes extended to one or both of the one side and the other side in the axial direction and arranged to face the outer peripheral side of the driving coil with a gap therebetween Or, both are provided.
As described above, since the magnetic yoke having the L-shaped or U-shaped cross section contacting the magnetic pole surface of the driving magnet and the surface perpendicular to the axial direction is provided, the magnetic field from the driving magnet is applied to the driving coil. Can be effectively led to. Therefore, the driving force and the linearity of the operation of the electromagnetic drive device can be further improved.

The invention according to claim 3 is the electromagnetic drive device according to claim 1 or 2, wherein the movable member is supported by a spring member so as to be movable with respect to the fixed member. To do.
Thereby, it is possible to support the movable member so as to be movable in the axial direction of the movable member with a simple configuration.
A fourth aspect of the present invention is the electromagnetic drive device according to the first or second aspect, wherein the movable member includes a ring member made of a soft magnetic material, an auxiliary magnet, and the movable member in the axial direction. A support member having a guide member that guides to the fixed member is movably supported with respect to the fixed member, and either the ring member or the auxiliary magnet is attached to the fixed member, and the other is attached to the movable member. It is characterized by being.
Accordingly, the movable member can be supported so as to be reliably movable in the axial direction of the movable member, and thus the movable member can be stably moved. In addition, there is an advantage that the initial position of the movable member can be easily changed only by changing the shape of the auxiliary magnet, the strength of magnetization, the shape of the ring member, and the like.

  The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a longitudinal cross-sectional view which shows the structure of the lens drive device which concerns on Embodiment 1 of this invention. FIG. 3 is a perspective view and a cross-sectional perspective view of a main part of a driving unit of the lens driving device according to the first embodiment. 1 is an exploded perspective view of a lens driving device according to Embodiment 1. FIG. It is a figure which shows the arrangement | positioning and dimension symbol of the drive coil in the lens drive device concerning Embodiment 1, and the conventional lens drive device, a drive magnet, and a magnetic yoke. It is sectional drawing which shows distribution of the magnetic field of the drive part vicinity in the lens drive device concerning Embodiment 1, and the conventional lens drive device. It is a figure which shows magnetic flux density distribution of the Z-axis direction in the lens drive device which concerns on Embodiment 1, and the conventional lens drive device. It is the figure which compared the drive sensitivity of the lens drive device of Embodiment 1 and the conventional lens drive device. It is the figure which compared the displacement characteristic of the lens drive device of this Embodiment 1, and the conventional lens drive device. It is a figure which shows the other example of the lens drive device by this invention. It is a figure which shows the other structure of the drive part of the lens drive device by this invention. It is a figure which shows the lens drive device which reduced the external dimension OD. It is the figure which compared the lens drive device of this invention which reduced the external dimension OD, and the conventional lens drive device. It is a figure which shows the structure of the lens drive device which further reduced the external dimension OD. It is a figure which shows the structure of the lens drive device which concerns on this Embodiment 2. FIG. It is a disassembled perspective view of the lens drive device concerning this Embodiment 2. FIG. It is a figure which shows the structure of the linear actuator which concerns on this Embodiment 3. FIG. It is a figure which shows the other example of the linear actuator by this invention. It is a figure which shows the structure of the lens drive device of the conventional electromagnetic drive system. It is a figure which shows the conventional lens drive device which reduced the external dimension OD.

  Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration of a lens driving device 10 as an electromagnetic driving device according to the first embodiment, and FIGS. 2A and 2B are a perspective view of a main part and a cross-sectional perspective view of a main part of a driving unit 10K. FIG. 3 is an exploded perspective view. In each figure, 12 is a lens holder as a movable member, 13 is a case as a fixed member, 14A and 14B are spring members for suspending and supporting the lens holder 12 on the case 13, 15 is a driving coil, and 16 is a driving member. A magnet, 17A is an inner magnetic yoke, and 17B is an outer magnetic yoke. The driving coil 15, the driving magnet 16, the inner magnetic yoke 17 </ b> A, and the outer magnetic yoke 17 </ b> B constitute a driving unit 10 </ b> K of the lens driving device 10.
The lens holder 12 is a member having a cylindrical holder main body 12a that holds a lens 11 that is a combination of an objective lens and an eyepiece lens on the inner side, and the axial direction of the holder main body 12a is that of the lens 11 when the lens 11 is mounted. It coincides with the direction of the optical axis. Hereinafter, the axial direction of the holder main body 12a is referred to as the Z-axis direction, and the subject direction when the lens 11 is mounted as indicated by the arrow in FIG.
A hollow disc-shaped flange portion 12b that protrudes outside the holder body 12a is provided behind the holder body 12a of the lens holder 12 in the Z-axis direction. In addition, a coil support portion 12c that protrudes forward from the flange portion 12b to the Z-axis is provided at the outer edge portion of the flange portion 12b.

As shown in FIG. 3, the case 13 has a square plate-like pedestal 13a with a circular opening 13h formed at the center, and four drives provided so as to protrude upward at the four corners of the pedestal 13a. And a locking portion 13c provided on the inner edge side of the opening 13h so as to protrude toward the lens holder 12 and abutting against the rear end of the lens holder 12. The drive unit support column 13b is formed with an attachment step 13k for attaching the outer peripheral side of the outer magnetic yoke 17B on the opening 13h side.
As shown in FIG. 3, each of the spring members 14A and 14B includes an annular outer ring 14a, an annular inner ring 14b, and four substantially arc-shaped arm portions 14c that connect the outer ring 14a and the inner ring 14b. Is provided. Hereinafter, the spring member 14A disposed in front of the Z axis is referred to as a front spring member, and the spring member 14B disposed in the rear of the Z axis is referred to as a rear spring member. The outer ring 14 a of the front spring member 14 </ b> A is fixed to the upper end side of the drive unit support column 13 b of the case 13, and the inner ring 14 b is fixed to the outer edge of the lens holder 12 in front of the Z axis. On the other hand, the outer ring 14a of the rear spring member 14B is fixed between the opening 13h of the pedestal 13a of the case 13 and the drive unit support column 13b, and the inner ring 14b is fixed to the outer edge of the lens holder 12 at the rear of the Z axis. . The four arm portions 14c function as springs that suspend and support the lens holder 12 on the case 13 so as to be movable in the Z-axis direction.
In this example, the case 13 is provided with a locking portion 13c that comes into contact with the rear end of the lens holder 12, and the spring members 14A and 14B are offset so that the lens holder 12 is always urged rearward in the Z-axis direction. Yes.

As shown in FIGS. 2A and 2B, the drive unit 10 </ b> K includes a drive coil 15 that is wound around the Z axis and has an annular shape, and a drive coil 15 that is in front of the Z axis of the drive coil 15. And a driving magnet 16 disposed coaxially and annularly with a gap, and an inner magnetic yoke 17A and an outer magnetic yoke 17B respectively disposed on the inner peripheral surface side and the outer peripheral surface side of the driving magnet.
The driving coil 15 is attached to the coil support portion 12 c of the lens holder 12.
As shown by the thick arrow in FIG. 2B, the drive magnet 16 is radiated with respect to the axis of the holder body 12a of the lens holder 12, that is, in a direction perpendicular to the Z axis in a plane including the Z axis. Magnetized.
The magnetic pole surface of the driving magnet 16 is, for example, an N-pole on the inner peripheral surface side and an S-pole on the outer peripheral surface side. Therefore, the driving coil 15 of this example is arranged in the axial direction of the lens holder 12 of the driving magnet 16. The front surface is coaxial with the drive magnet 16 and faces a surface different from the magnetic pole surface of the drive magnet 16 with a gap. The driving magnet 16 may be an annular magnet or an arc-shaped magnet arranged in a ring.
The inner magnetic yoke 17A is made of a soft magnetic material such as soft iron, and an annular portion 171 disposed in contact with the inner peripheral side magnetic pole surface of the driving magnet 16 and a direction perpendicular to the Z axis from the rear of the annular portion 171 in the Z axis. A flange portion 172 that protrudes so as to face the inner peripheral side of the winding portion of the drive coil 15 with a gap therebetween is provided.
The outer magnetic yoke 17B includes an annular portion 173 disposed in contact with the outer peripheral side magnetic pole surface of the driving magnet 16 and a winding portion of the driving coil 15 in a direction perpendicular to the Z axis from the Z axis rear side of the annular portion 173. A flange portion 174 that protrudes so as to face the outer peripheral side with a gap is provided. The outer magnetic yoke 17B is also made of a soft magnetic material such as soft iron.

In the drive unit 10K, the drive coil 15 is disposed between the outer peripheral surface of the flange portion 172 of the inner magnetic yoke 17A and the inner peripheral surface of the flange portion 174 of the outer magnetic yoke 17B. The lines of magnetic force from the N pole, which is the inner peripheral surface of the drive magnet 16, are mainly guided from the annular portion 171 of the inner magnetic yoke 17A through the flange portion 172 to the flange portion 174 of the outer magnetic yoke 17B. Since the S pole, which is the outer peripheral surface of the driving magnet 16, passes through the flange portion 174 of 17 </ b> B, the driving coil 15 intersects with a magnetic flux that faces in a direction opposite to the magnetization direction of the driving magnet 16. Therefore, when the drive coil 15 is energized, a Lorentz force is generated in the drive coil 15 that faces the front of the Z axis or the rear of the Z axis.
Even in the absence of the inner magnetic yoke 17A and the outer magnetic yoke 17B, the driving coil 15 intersects with a magnetic flux that is substantially opposite to the magnetization direction of the driving magnet 16, but in this example, the inner magnetic yoke 17A and Since the outer magnetic yoke 17B is provided, the magnetic flux between the outer peripheral surface of the flange portion 172 of the inner magnetic yoke 17A where the driving coil 15 is disposed and the inner peripheral surface of the flange portion 174 of the outer magnetic yoke 17B. The density can be made high and uniform. As a result, the driving coil 15 generates a strong and uniform Lorentz force as compared with the case where the inner magnetic yoke 17A and the outer magnetic yoke 17B are not provided, so that the driving force is strong and has excellent linearity. Can be obtained. Therefore, in the lens driving device 10 of this example, the lens holder 12 can be efficiently and accurately moved to a position that balances the restoring force of the front and rear spring members 14A and 14B.

図４（ａ），（ｂ）に示すように、従来のレンズ駆動装置５０では、駆動用磁石５２の内周側に、駆動用コイル５５とヨーク５１のインナー部５１ｂとがそれぞれ空隙を隔てて配設されているのに対し、本実施の形態１のレンズ駆動装置１０では、駆動用コイル１５が駆動用磁石１６のＺ軸後方に配設されている。したがって、レンズ駆動装置１０では、駆動用磁石１６を径方向に拡大できるので、駆動用磁石１６を径方向に厚い形状、すなわち、外径と内径との差の大きな形状にすることができる。 Next, the performance of the lens driving device 10 shown in FIG. 1 will be described in comparison with the conventional lens driving device 50 shown in FIG.
FIG. 4A is a diagram showing the arrangement and dimension symbols of the driving coil 15, the driving magnet 16, the inner magnetic yoke 17A, and the outer magnetic yoke 17B constituting the driving unit 10K of the lens driving device 10. FIG. 4B is a diagram showing the arrangement and dimensional symbols of the drive coil 55, the drive magnet 52, and the yoke 51 that constitute the drive unit 50 </ b> K of the conventional lens drive device 50. Specific dimension values corresponding to the dimension symbols are shown in Table 1 below.

As shown in FIGS. 4A and 4B, in the conventional lens driving device 50, the driving coil 55 and the inner portion 51b of the yoke 51 are spaced apart from each other on the inner peripheral side of the driving magnet 52. In contrast, in the lens driving device 10 according to the first embodiment, the driving coil 15 is disposed behind the driving magnet 16 in the Z-axis. Therefore, in the lens driving device 10, since the driving magnet 16 can be expanded in the radial direction, the driving magnet 16 can be made thick in the radial direction, that is, a shape having a large difference between the outer diameter and the inner diameter.

FIG. 5A is a cross-sectional view showing the distribution of the magnetic field in the vicinity of the driving unit 10K in the lens driving device 10, and FIG. 5B shows the distribution of the magnetic field in the vicinity of the driving unit 50K in the conventional lens driving device 50. It is sectional drawing.
In the conventional lens driving device 50, the magnetic force lines intersecting the driving coil 55 are inclined from the radial direction in front of the moving range, whereas in the lens driving device 10, the magnetic force lines intersecting the driving coil 15 are substantially linear. It turns out that it is applied efficiently toward the radiation direction.
When the drive coil 15 and the drive coil 55 are energized, Lorentz force is generated in the drive coil 15 and the drive coil 55. Therefore, the drive coil 15 and the drive coil 55 are respectively shown in FIG. It moves in the direction of the arrow of the Z axis shown in (b) (front of the Z axis).
In the lens driving device 10, before energization, the position in the Z-axis direction of the point P on the average winding diameter of the Z-axis rear end (hereinafter referred to as the lower end) of the driving coil 15 is the inner magnetic yoke 17 </ b> A and The lower end of the outer magnetic yoke 17B is at the same position as the position in the Z-axis direction. When energized, the end on the Z-axis front side of the drive coil 15 (hereinafter referred to as the upper end) contacts the lower end Q of the drive magnet 16. Move to touching position.
In the conventional lens driving device 50, the position in the Z-axis direction of the point P ′ on the winding average diameter at the lower end of the driving coil 55 is the same position as the position in the Z-axis direction of the lower end of the driving magnet 52; By energization, the upper end of the driving coil 55 moves to a position where it abuts on the lower end Q ′ of the connecting portion 51c.
As shown in FIGS. 4A and 4B and Table 1, the distance (H _y −H _m ) between the point P and the point Q that is the movable range of the driving coil 15 of the lens driving device 10 and the driving The winding height of the coil 15 (the difference from H _c and the distance between the points P ′ to Q ′ that are the movable range of the conventional lens driving device 50 (the height H _m of the driving magnet) and the driving The difference from the height (H _c ) of the coil 55 winding is 0.3 mm.

FIG. 6 is a diagram showing the magnetic flux density distribution in the Z-axis direction in the movement range of the driving coils 15 and 55 in the lens driving device 10 of the first embodiment and the conventional lens driving device 50. FIG. The horizontal axis of the figure is the distance [mm] between the point P or the point P ′ and the point P or the point P ′ and the measurement point, and the vertical axis is the magnetic flux density [Tesla]. Further, in the figure, the ◯ marks indicate data of the lens driving device 10, and the X marks indicate data of the conventional lens driving device 50.
As shown in FIG. 6, in the conventional lens driving device 50, the magnetic flux density changes rapidly. Although the magnetic flux density is partially larger than that of the lens driving device 10 of the first embodiment, the magnetic flux density is near the point P ′ (h = 0 mm) and near the point Q ′ (h = 1 mm). It can be seen that the decrease in As described above, in the conventional lens driving device 50, the driving coil 55 having a high winding height and thin in the radial direction is disposed in a region where the magnetic flux density is rapidly changed. Is widely wound even in a region where the magnetic flux density is low. As a result, the total amount of magnetic flux that intersects the driving coil 55 is reduced.

On the other hand, in the lens driving device 10 according to the first embodiment, the magnetic flux density is flat, and a high magnetic flux density is obtained over the entire area between the points P and Q (h = 0 to 0.5 mm). Maintained. In addition, since the drive coil 15 is disposed behind the Z axis of the drive magnet 16, the cross-sectional shape of the winding can be made wider in the radial direction in accordance with the dimensions of the drive magnet 16. That is, the driving coil 15, it is possible to winding height H _c of the Z-axis direction is small flat wide.
As described above, in the lens driving device 10, the driving coil 15 can be arranged in a flat and high magnetic flux density area, so that the total amount of magnetic flux that intersects the driving coil 15 even when the lens holder 12 moves in the Z-axis direction. The change in (number of magnetic field lines) is small.
The above suggests that the lens driving device 10 is a high linearity lens driving device having a large driving force per unit current and hardly changing, that is, a stable driving sensitivity. This is demonstrated below.
FIG. 7 is a diagram comparing the driving sensitivities of the lens driving device 10 according to the first embodiment and the conventional lens driving device 50. In the figure, the horizontal axis represents the moving distance [mm] of the driving coils 15 and 55, the vertical axis represents the driving sensitivity [mN / mA], the ◯ mark represents the data of the lens driving apparatus 10, and the X mark represents the conventional lens driving apparatus. 50 data.
As shown in the figure, the driving sensitivity of the lens driving device 10 is 16 to 41% larger than the driving sensitivity of the conventional lens driving device 50, and is stable at a substantially constant level.

このように、実施の形態１のレンズ駆動装置１の変位特性は、感度が高くかつリニアリティに優れていることが分かる。 FIG. 8 is a diagram comparing the displacement characteristics of the lens driving device 10 of the first embodiment and the conventional lens driving device 50, where the horizontal axis is the drive current [mA], and the vertical axis is the movement amount (displacement) of the lens holder 12. Amount) [mm]. A circle indicates data of the lens driving device 10, and a cross indicates data of the conventional lens driving device 50.
In the lens driving device 10, as shown in FIG. 1, the lens holder 12 is suspended and supported on the case 13 by a front spring member 14A and a rear spring member 14B. At this time, the front and rear spring members 14A and 14B are bent by applying a bending moment so that the fulcrum position on the case 13 side is behind the fulcrum position on the lens holder 12 side. It is attached to the case 13 and the lens holder 12 so as to be in a state.
Also in the conventional lens driving device 50, as shown in FIG. 18, the lens holder 54 is suspended and supported on the case 56 by the front plate spring 57A and the rear plate spring 57B, and the front and rear plate springs. 57A and 57B are arranged so as to be bent with a bending moment so that the position of the fulcrum on the case 56 side is behind the Z-axis from the position of the fulcrum on the lens holder 54 side. It is attached to the lens holder 54.
The spring coefficients of the front and rear spring members 14A and 14B and the spring coefficients of the front and rear leaf springs 57A and 57B are the same. In addition, the same offset amount of 0.1 mm is applied to both the lens holder 12 and the lens holder 54.
As is apparent from FIG. 8, in the lens driving device 10, the lens holder 12 starts moving forward in the Z axis when the driving current reaches 25 mA, whereas in the conventional lens driving device 50, the driving current is When reaching 29 mA, the lens holder 54 starts moving forward in the Z axis. This is because the driving sensitivity of the lens driving device 10 when the lens holder 12 is moved is 16% higher than that of the conventional lens driving device 50 as shown in FIG.
Further, as the drive current is increased, the difference in displacement amount increases. This is because, as shown in Table 2 below, the difference in displacement sensitivity with respect to the drive current increases as the lens holder advances. That is, the driving sensitivity of the lens driving device 10 is substantially constant and stable, whereas in the conventional lens driving device 50, the driving sensitivity is halved at the maximum displacement position, and the change is remarkable.

Thus, it can be seen that the displacement characteristics of the lens driving device 1 of Embodiment 1 are high in sensitivity and excellent in linearity.

  In the first embodiment, the driving coil 15 is disposed behind the Z-axis of the driving magnet 16. However, as shown in FIG. 9A, the driving coil 15 is positioned in front of the Z-axis of the driving magnet 16. May be arranged. At this time, the flange portion 172 of the inner magnetic yoke 17A and the flange portion 174 of the outer magnetic yoke 17B are configured to protrude forward in the Z-axis direction, that is, to face the drive coil 15 with a gap. The driving coil 15 is disposed at a position where it abuts on the upper end side of the driving magnet 16. In this case as well, in the same manner as in the first embodiment, the gap between the outer peripheral surface of the flange portion 172 of the inner magnetic yoke 17A and the inner peripheral surface of the flange portion 174 of the outer magnetic yoke 17B, where the drive coil 15 is disposed. Since the magnetic flux density is large and uniform, a driving force that is strong and excellent in linearity can be obtained. Therefore, the lens holder 12 can be efficiently and accurately moved to a position that balances the restoring force of the front and rear spring members 14A and 14B.

Alternatively, as shown in FIG. 9B, the front and rear drive coils 15A and 15B may be arranged on the front side and the rear side of the Z axis of the drive magnet 16, respectively. In this case, two front and rear flange portions 175 and 176 are provided on the inner magnetic yoke 17A, and two front and rear flange portions 177 and 178 are provided on the outer magnetic yoke 17B. 15A is arranged between the outer peripheral surface of the front flange portion 175 of the inner magnetic yoke 17A and the inner peripheral surface of the front flange portion 177 of the outer magnetic yoke 17B, and the rear drive coil 15B is a rear flange portion of the inner magnetic yoke 17A. If it is arranged between the outer peripheral surface of 176 and the inner peripheral surface of the rear flange portion 178 of the outer magnetic yoke 17B, the magnetization direction of the driving magnet 16 in the front and rear driving coils 15A and 15B is as follows. Magnetic fluxes facing in opposite directions can be efficiently crossed.
At this time, the lower end of the front drive coil 15A is disposed at a position in contact with the upper end of the drive magnet 16, and the lower end of the rear drive coil 15B is disposed at the lower ends of the inner magnetic yoke 17A and the outer magnetic yoke 17B. If the front and rear drive coils 15A and 15B are energized so as to generate a low lens force directed to the front of the Z axis as indicated by the arrows in the figure, the lens holder 12 is efficiently driven forward of the Z axis. be able to.

  In the arrangement of FIG. 9B, between the outer peripheral surface of the flange portions 175 and 176 before and after the inner magnetic yoke 17A and the inner peripheral surface of the flange portions 177 and 178 before and after the outer magnetic yoke 17B. The magnetic flux density is large and uniform, and when the front drive coil 15A is close to the drive magnet 16, the rear drive coil 15B is separated from the drive magnet 16, and the front drive coil 15A is the drive magnet 16. Since the rear drive coil 15B is closer to the drive magnet 16 when it is away from the front, the front and rear drive coils 15A and 15B can compensate for the difference in Lorentz force due to the difference in distance from the drive magnet 16. As a result, the uniformity of the driving force is further improved. In addition, since the number of turns increases, the lens driving device 10 with higher driving sensitivity can be obtained.

  In the above example, the inner magnetic yoke 17A and the outer magnetic yoke 17B are separately formed. However, as shown in FIG. 10, a connecting portion 17C for connecting the inner magnetic yoke 17A and the outer magnetic yoke 17B is provided. Alternatively, the inner magnetic yoke 17A and the outer magnetic yoke 17B may be connected to each other, and the inner magnetic yoke 17A and the outer magnetic yoke 17B may be configured integrally.

Moreover, in the said example, although the drive magnet 16 was made into an annular | circular shape, as shown to Fig.11 (a)-(d), an outer peripheral part can be cut into a rectangular shape, and external dimensions can be made. Further reduced lens drive device 10A can be obtained. 4A is a plan view showing the drive magnet 16, the inner magnetic yoke 17A, and the outer magnetic yoke 17B, and FIG. 4B is a plan view showing an example in which the drive coil 15 is disposed behind the Z axis of the drive magnet 16. FIG. FIGS. 2C and 2C are cross-sectional views taken along the cut line AA ′ in the diagonal direction of FIG. 2B, and FIG. 4D is a cross-sectional view taken along the cut line BB ′ in the side direction of FIG. 11A to 11D, the case 13 and the front and rear spring members 14A and 14B are omitted.
As shown in FIGS. 11A and 11B, the inner magnetic yoke 17A remains in an annular shape, but the outer magnetic yoke 17B has a rectangular shape as the outer dimensions are reduced. As shown in FIGS. 11C and 11D, the inner peripheral surface and the outer peripheral surface of the driving coil 15 have gaps between the outer peripheral surface of the inner magnetic yoke 17A and the inner peripheral surface of the outer magnetic yoke 17B, respectively. They are arranged opposite to each other in a direction perpendicular to the Z axis.
By adopting such a configuration, the driving magnet 16 is driven by the driving magnet 52 of the lens driving device (hereinafter referred to as the lens driving device 50A) in which the external dimensions of the conventional lens driving device 50 shown in FIG. 19 are reduced. In addition, since it can be enlarged in the inner diameter direction, the driving magnet 16 can be disposed over the entire circumference of the driving coil 15. Accordingly, the magnetic fluxes can be crossed over the entire circumference of the driving coil 15, so that a large driving force can be obtained.

FIG. 12 is a diagram comparing the lens driving device 10A with a reduced outer dimension OD and the lens driving device 50A. The left half is the lens driving device 10A and the right half is the conventional lens driving device 50A. This figure also omits the case 13, the case 56, the front and rear spring members 14A and 14B, and the front and rear leaf springs 57A and 57B.
As can be seen from the figure, in the lens driving device 10A, since the driving coil 15 does not exist on the inner peripheral side of the driving magnet 16, the inner peripheral side of the driving magnet 16 is enlarged and thickened in the radial direction. In contrast, in the lens driving device 50A, since the driving coil 55 exists on the inner peripheral side of the driving magnet 52, the driving magnet 52 is provided at the center of the four sides of the rectangular portion on the outer peripheral side. It can be seen that there is no space, and as a result, the drive magnet 52 can be disposed only at the four corners of the outer portion 51 a of the yoke 51.
As described above, the lens driving device 10A having the reduced outer dimension OD can arrange the driving magnet 16 over the entire circumference of the driving coil 15, so that the magnetic flux can intersect the entire circumference of the driving coil 15. . Therefore, the use efficiency of the driving coil 15 can be increased, and high sensitivity and high linearity can be maintained even when the lens driving device 10 is downsized.

FIGS. 13A and 13B are diagrams showing the configuration of the lens driving device 10B in which the outer dimensions of the lens driving device 10A are further reduced. The driving magnet 16 is divided into four corners of a rectangular case (not shown). The inner magnetic yoke 17A and the outer magnetic yoke 17B are also divided and arranged at the four corners of a rectangular case (not shown).
In this case, the driving force is reduced as compared with the lens driving device 10A described above, but the thickness in the radial direction of the driving magnets 16 divided and disposed at the four corners is the lens driving device 50A shown in FIG. The thickness of the drive magnet 52 can be larger than the radial thickness of the drive magnet 52, so that not only the magnetic field from the drive magnet 16 is strengthened, but also the length of the drive magnet 16 facing the drive coil 15 ( Since the opposing length in the circumferential direction can be increased, the amount of magnetic flux intersecting the drive coil 15 increases. Accordingly, it is possible to obtain a lens driving device 10B that is smaller and more sensitive than the lens driving device 50A.

Embodiment 2. FIG.
FIG. 14 is a diagram showing a configuration of a lens driving device 20 as an electromagnetic driving device according to the second embodiment, and FIG. 15 is an exploded perspective view.
The lens driving device 20 includes a lens holder 21, a case 22, a driving coil 15, a driving magnet 16, an inner magnetic yoke 17A, an outer magnetic yoke 17B, a guide pin 23, a slide guide 24, and a circle. An annular auxiliary magnet 25 and a suction ring 26 are provided. Since the parts having the same reference numerals as in the first embodiment from the driving coil 15 to the outer magnetic yoke 17B and the arrangement thereof are the same as those in the first embodiment, the description thereof is omitted.
The lens holder 21 is provided on the inner side with a cylindrical holder main body 21a for holding the lens 11 composed of a combination of an objective lens and an eyepiece lens, and a hollow projecting to the outside of the holder main body 21a. A disc-shaped flange portion 21b and a coil support portion 21c provided so as to protrude forward from the outer edge portion of the flange portion 21b in the Z-axis direction are provided. An auxiliary magnet 25 is attached to the lower end of the holder body 21a, and a slide guide 24 having a guide hole 24h is attached to the side surface of the coil support portion 21c.
On the other hand, the case 22 includes a square plate-like pedestal 22a with a circular opening 22h formed in the center, and four drive unit support columns 22b provided to protrude upward at the four corners of the pedestal 22a. The guide pin 23 is provided so as to protrude forward from the center of the side forming the outer periphery of the base 22a. The guide pin 23 is inserted into the guide hole 24h of the slide guide 24, and supports the lens holder 21 so as to be movable in the Z-axis direction.
The attraction ring 26 is an annular member made of a soft magnetic material, and urges a force to pull the lens holder 21 backward in the Z axis by an attraction force acting between the auxiliary magnet 25 and the attraction ring 26.
Similarly to the first embodiment, the driving coil 15 includes the outer peripheral surface of the flange portion 172 of the inner magnetic yoke 17A and the flange portion of the outer magnetic yoke 17B, which are disposed on the inner peripheral side and the outer peripheral side of the driving magnet 16, respectively. Since it is arranged between the inner peripheral surface of 174, the driving coil 15 intersects with a magnetic flux directed in a direction opposite to the magnetization direction of the driving magnet 16. Accordingly, when the drive coil 15 is energized, a Lorentz force is generated in the drive coil 15 that faces the front or rear of the Z axis, so that the lens holder 21 has the Lorentz force, the auxiliary magnet 25, the suction ring 26, It moves to a position where the suction force acting between the two is balanced.
As described above, in the second embodiment, instead of the spring members 14A and 14B, the lens holder 21 is pulled back by the suction ring 26 and the auxiliary magnet 25, and the lens holder 21 is guided by the guide pin. 23, the lens holder 21 can be reliably moved in the Z-axis direction.

Embodiment 3 FIG.
FIGS. 16A and 16B are views showing the configuration of a linear actuator 30 as an electromagnetic drive device. FIG. 16A is a perspective view showing the appearance of the linear actuator 30, and FIG. 16B is a cross-sectional view. .
In each figure, 31 is a case as a fixed member, 32 is a movable shaft as a movable member, 33A and 33B are drive coils, 34 is a drive magnet, and 35 is an outer magnetic yoke.
Hereinafter, the extending direction of the movable shaft 32 is referred to as the Z-axis direction, the upper side in FIG. 16 is referred to as the Z-axis front, the lower side is referred to as the Z-axis rear, the driving coil 33A is the front driving coil and the driving coil 33B is the rear driving. It is called a coil for use.
The case 31 includes a cylindrical cylindrical body 31a, and an upper lid 31b and a lower lid 31c that are attached to the cylindrical body 31a on the front side and the rear side of the Z axis, respectively, and have a through-hole into which a movable shaft 32 is inserted. An outer magnetic yoke 35 that holds a driving magnet 34 is attached to the inner peripheral side of the cylindrical body 31a.
The movable shaft 32 is a cylindrical member extending in the Z-axis direction, and driving coils 33A and 33B are wound and held coaxially with the movable shaft 32 at the front and rear of the outer peripheral surface in the Z-axis direction. . The front drive coil 33A is positioned forward of the drive magnet 34 in the Z-axis direction, and the rear drive coil 33B is positioned rearward of the drive magnet 34 in the Z-axis direction.
The outer magnetic yoke 35 is an annular member in which a mounting recess 35 s is formed on the side surface of the movable shaft 32 that is the inner peripheral surface, and the annular drive magnetized in the direction perpendicular to the Z axis in the mounting recess 35 s. A magnet 34 is attached. Further, the portions protruding from the movable shaft 32 (hereinafter referred to as guide portions), which are the front and rear portions of the mounting recess 35s of the outer magnetic yoke 35, respectively face the drive coils 33A and 33B with a gap therebetween. doing.

As a result, the driving coils 33A and 33B are crossed by magnetic fluxes in the direction opposite to the magnetization direction of the driving magnet 34. Therefore, when the driving coils 33A and 33B are energized, the driving coils 33A and 33B have Z A Lorentz force that faces the front of the shaft or the rear of the Z-axis is generated. Therefore, the movable shaft 32 can be moved with high accuracy in the Z-axis direction.
At this time, if the movable shaft 32 is made of a soft magnetic material, the movable shaft 32 can have the same function as that of the inner magnetic yoke 17A of the first embodiment. Therefore, the magnetic flux density intersecting with the drive coils 33A and 33B. Can be increased. Therefore, by energizing the drive coils 33A and 33B, the movable shaft 32 can be driven more strongly in the Z-axis direction, and the linearity of drive sensitivity can be further improved.

In the third embodiment, the drive coils 33A and 33B are disposed on the front and rear sides of the Z axis of the drive magnet 34. However, as shown in FIG. The front and rear drive magnets 34 </ b> A and 34 </ b> B may be held on the movable shaft 32 coaxially with the movable shaft 32.
In this case, the cylindrical outer magnetic yoke 35 is disposed on the inner peripheral side of the case 31, and the driving coil 33 is disposed at the center of the inner peripheral surface of the outer magnetic yoke 35. The front and rear drive magnets 34A and 34B are formed in an annular shape magnetized in a direction orthogonal to the Z axis, and the front drive magnet 34A is positioned in front of the drive coil 33 in the Z axis direction. What is necessary is just to arrange | position so that the magnet 34B may be located in the Z-axis direction back of the drive coil 33. FIG. As a result, the driving coil 33 crosses with the magnetic flux directed in the direction opposite to the magnetization direction of the driving magnets 34A and 34B. Therefore, when the driving coil 33 is energized, the driving coil 33 is moved forward of the Z axis or Z A Lorentz force facing the rear of the shaft is generated. Since the driving coil 33 is attached to the case 31 which is a fixed member, the front and rear driving magnets 34A and 34B attached to the movable shaft 32 have a Z-axis rearward or Z-axis which is a reaction force of the Lorentz force. Since the force directed toward the front of the axis acts, the movable shaft 32 can be moved with high accuracy in the Z-axis direction.
Also in this case, if the movable shaft 32 is made of a soft magnetic material, the movable shaft 32 can have the same function as the inner magnetic yoke 17A, so that the movable shaft 32 can be driven more strongly in the Z-axis direction, The linearity of drive sensitivity can be further improved.
The linear actuator 30 according to the third embodiment can be used not only as a driving source for movement and vibration but also as a sound generator such as a speaker.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, since a uniform and strong magnetic field can be efficiently applied to the driving coil, an electromagnetic driving device excellent in driving force and linearity and capable of being miniaturized can be provided.

10 lens driving device, 11 lens, 12 lens holder,
12a holder body, 12b flange part, 12c coil support part, 13 case,
13a pedestal, 13b driving part supporting column, 13c locking part, 13h opening,
13k mounting step, 14A front spring member, 14B rear spring member,
15 driving coil, 16 driving magnet, 17A inner magnetic yoke,
17B Outer magnetic yoke.

Claims (4)

A columnar or cylindrical movable member, a fixed member that supports the movable member so as to be movable in the axial direction of the movable member, a driving coil wound around the axis of the movable member, and the axis An electromagnetic drive device comprising a drive magnet magnetized in the radial direction,
The driving magnet is arranged around an axis of the movable member;
The driving coil is coaxial with the driving magnet on one side or both sides of one side in the axial direction of the driving magnet and the other side in the axial direction, and the driving magnet. An electromagnetic driving device, wherein the electromagnetic driving device is disposed so as to be opposed to a surface different from the magnetic pole surface with a gap. It extends from the inner peripheral side magnetic pole surface of the driving magnet to one or both of one side in the axial direction of the movable member and the other side in the axial direction so as to separate the gap from the inner peripheral side of the driving coil. Inner magnetic yokes disposed opposite to each other,
Extending from the outer peripheral side magnetic pole surface of the driving magnet to one or both of the one side in the axial direction of the movable member and the other side in the axial direction, and the gap between the outer peripheral side of the driving coil and the gap The electromagnetic drive device according to claim 1, comprising either one or both of outer magnetic yokes arranged to face each other at a distance.   The electromagnetic drive device according to claim 1, wherein the movable member is supported by a spring member so as to be movable with respect to the fixed member. The movable member is
Supported by a support means including a ring member made of a soft magnetic material, an auxiliary magnet, and a guide member for guiding the movable member in the axial direction, so as to be movable with respect to the fixed member;
3. The electromagnetic drive device according to claim 1, wherein one of the ring member and the auxiliary magnet is attached to the fixed member, and the other is attached to the movable member.

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