JP2016036254A - Linear type vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear type vibration actuator by which the location accuracy of a coil in a case can be increased easily.SOLUTION: In a linear type vibration actuator 1, a magnetic circuit is formed by a magnet 13 with a weight 15 fixed thereto and a shaft 20 in a case 2, and a coil 24 causes the weight 15 and the magnet 13 to reciprocate in the case 2. The vibration actuator 1 comprises: the shaft 20 provided upright on the case 2 and made of a magnetic material; the coil 24 supported by the shaft 20 and having a first coil part 22 and a second coil part 23 which are arrayed in parallel along a direction of an axial line L and are wound in directions opposite to each other; the ring-shaped magnet 13 disposed so as to surround the coil 24 and the shaft 20; the weight 15 fixed to the magnet 13; and a leaf spring 17 disposed in the case 2, and serving to urge the magnet 13 and the weight 15 toward the direction of the axial line L of the shaft 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a linear vibration actuator that generates vibrations when a weight reciprocates.

  Conventionally, there is JP, 2011-30403, A as a technique of such a field. The linear vibration actuator described in this publication is one in which a weight linearly vibrates up and down by the interaction between a magnetic force generated by a magnet and an electromagnetic force having a predetermined frequency generated in a coil portion. The ring-shaped coil is fixed on the circuit board, and the magnet is fixed to the bottom of the cup-shaped yoke. Is fixed. Further, the bottom of a truncated cone-shaped spring made of a thin plate is fixed to the bottom surface of the cylindrical case, and the outer surface of the yoke is fixed to the top of the spring. The cylindrical coil is fixed on the circuit board and is disposed so as to enter and leave the gap between the inner peripheral surface of the cylindrical portion of the cup and the outer peripheral surface of the magnet. Accordingly, when a current having a predetermined frequency is input (energized) to the coil, the weight can be vibrated in the up-and-down motion by the cooperation of the magnet and the coil.

JP 2011-30403 A

However, in the conventional linear type vibration actuator described above, the coil enters and exits the gap between the inner peripheral surface of the cylindrical portion of the cup-shaped yoke and the outer peripheral surface of the magnet, so that the coil is accurately fixed on the circuit board. Otherwise, the coil will move closer to the inner peripheral surface of the yoke cylinder or to the outer peripheral surface of the magnet, so that it may collide with the inner peripheral surface of the yoke or the outer peripheral surface of the magnet during a drop impact. Becomes higher. Therefore, in order to fix the coil in an accurate position in the case, it is necessary to fix the coil in an accurate position in advance on the circuit board before assembling the actuator. A special configuration for coil positioning is required on the coil side, and when such measures are not taken, a special jig for accurately fixing the coil to the circuit board is required. For this reason, there is a problem that it is difficult to increase the positional accuracy of the coil in the case.

  It is an object of the present invention to provide a linear vibration actuator that can easily increase the positional accuracy of a coil in a case.

The present invention is a linear vibration actuator in which a magnet and a weight are fixed and a weight and a magnet are reciprocated by a coil in a case.
A shaft that is erected in a case and that is made of a magnetic material and constitutes a magnetic circuit;
A coil supported by a shaft;
A ring-shaped magnet arranged to surround the coil and shaft;
A weight fixed to the magnet;
A biasing means disposed in the case and biasing the magnet and the weight in the axial direction of the shaft;
It is provided with.

  In this linear vibration actuator, a magnet and a shaft constitute a magnetic circuit, and the coil is supported by a shaft that forms part of the magnetic circuit, and is arranged so as to wind around the shaft. Therefore, the coil can be positioned by effectively using the shaft. That is, according to the present invention, it is possible to position the coil with reference to the shaft erected in the case, thereby easily increasing the position accuracy of the coil in the case.

A ring-shaped weight is fixed to the outer peripheral surface of the magnet, and the gap between the outer peripheral surface of the weight and the case is smaller than the gap between the inner peripheral surface of the magnet and the outer peripheral surface of the coil.
If such a configuration is adopted, the outer surface of the weight and the inner surface of the case do not collide with each other at the time of a drop impact. The coil is difficult to break.

The bobbin around which the coil is wound is disposed around the shaft, and the bobbin is provided with a partition portion that protrudes toward the inner peripheral surface of the magnet, and this partition portion is wound around the bobbin by reverse winding. It protrudes from the outer peripheral surfaces of the first coil portion and the second coil portion.
Such a configuration is intended to make effective use of a partition portion for partitioning the first coil portion and the second coil portion. That is, since the free end of the partitioning portion collides with the inner peripheral surface of the magnet at the time of a drop impact, a situation where the coil and the magnet do not collide occurs, and the coil is difficult to be disconnected due to the drop impact. In addition, this partition part makes it easy to wind the coil wire of a different winding direction around a bobbin.

Moreover, in the weight, the recessed part for mass adjustment of a weight is formed in the plane orthogonal to an axis.
By adopting such a configuration, vibration defects caused by individual differences in weights and urging means can be applied by inserting a filling liquid (for example, a mixture of tungsten powder and an adhesive) into a recess provided in the weight. It is possible to easily adjust the vibration failure on the weight side without adjusting the urging force of the urging means.

In addition, the magnet has a pair of ring-shaped plane portions facing each other, and a yoke is not fixed to each plane portion.
By adopting such a configuration, it is possible to increase the thrust of the weight fixed to the magnet compared to the linear vibration actuator of the type in which the coke is fixed to the flat part, and as a result, efficient vibration Can be obtained.

  According to the present invention, the positional accuracy of the coil in the case can be easily increased.

1 is an external perspective view showing a first embodiment of a linear vibration actuator according to the present invention. FIG. 2 is an exploded perspective view of the vibration actuator shown in FIG. 1. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which shows 2nd Embodiment of the linear vibration actuator which concerns on this invention. It is sectional drawing which compares and shows the type with which the yoke is not fixed to the magnet, and the type with which the yoke was fixed to the magnet.

  Hereinafter, preferred embodiments of a linear vibration actuator according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
As shown in FIGS. 1 to 3, the small linear vibration actuator 1 is incorporated in a communication device such as a mobile communication device (for example, a mobile phone) and has a diameter of about 10 mm that is used as a vibration generation source of the calling function. The coin shape is about 3mm thick.

  The case 2 of the vibration actuator 1 has a cup-shaped upper case portion 11 made of a nonmagnetic material (for example, stainless steel) and a disk shape made of a nonmagnetic material (for example, stainless steel) to close the open side of the upper case portion 11. The lower case part 12 is formed. The lower case part 12 is fitted inside the circular open end of the upper case part 11, and then the open end of the upper case part 11 is bent inward. The upper case portion 11 may be welded to the lower case portion 12.

  In the case 2, a ring-shaped magnet 13 is accommodated that is magnetized in the N pole and the S pole in the direction of the axis L of the shaft 20. The yokes 14 and 16 made of a ring-shaped thin magnetic material are fixed to the flat portions 13a and 13b of the magnet 13 with an adhesive so that the magnet 13 is sandwiched between the upper and lower sides. The yokes 14 and 16 have four cross-shaped adhesive filling holes 14a and 16a formed in the circumferential direction. Thereby, the adhesive effect by the adhesive is enhanced.

  An inner peripheral surface 15b of a donut-shaped weight 15 is bonded to the outer peripheral surface 13c of the magnet 13 with an adhesive. This weight 15 is made of, for example, tungsten, and the magnet 13, the yokes 14 and 16, and the weight 15 constitute a mover. And the thin flat spring 17 which makes an example of an urging means is being fixed to the lower side plane part 15a of the weight 15 by welding.

  The leaf spring 17 has an arcuate shape connecting the upper seating portion 17a having a small ring shape, the lower seating portion 17b having a large diameter ring shape, and the upper seating portion 17a and the lower seating portion 17b. Elastic piece 17c. The upper seat portion 17 a is welded to the lower flat portion 15 a of the weight 15, and the lower seat portion 17 b is welded to the inner wall surface of the lower case portion 12.

  The lower case portion 12 includes a disc-shaped main body portion 12a having a shape matching the open end of the upper case portion 11, and a tongue piece 12d protruding in the radial direction from the main body portion 12a. A flexible circuit board 19 is fixed to the inner wall surface of the lower case portion 12. The flexible circuit board 19 includes a ring-shaped main body portion 19 a placed on the inner wall surface of the lower case portion 12 and an extension portion 19 b placed on the tongue piece 12 d of the lower case portion 12. Yes. An opening 19d for inserting the bobbin 21 and the shaft 20 is formed in the main body 19a, and a power supply terminal 19c is provided in the extension 19b to expose the power supply terminal 19c to the outside.

  A press-fit hole 12c for standing the shaft 20 is provided at the center of the main body 12a of the lower case portion 12. A shaft 20 made of a magnetic material supports a resin bobbin 21. The bobbin 21 has a central hole 21a for inserting the shaft 20, flange portions 21b and 21c positioned at both ends in the direction of the axis L, and a flange-shaped partition portion 21d positioned between the flange portions 21b and 21c. ,have. The flange portion 21b, the partition portion 21d, and the column 21e constitute a first bobbin portion 21A, the flange portion 21c, the partition portion 21d, and the column 21f constitute a second bobbin portion 21B, and the first The bobbin portion 21A and the second bobbin portion 21B are juxtaposed in the direction of the axis L. Further, the shaft 20 is press-fitted or inserted with an extremely small error into the central hole 21a penetrating the support column 21e and the support column 21f.

  The coil 24 includes a first coil portion 22 in which a coil wire is wound around a support column 21e of the first bobbin portion 21A, and a coil wire connected to the first coil portion 22 of a support column 21f of the second bobbin portion 21B. It consists of the 2nd coil part 23 wound by the reverse direction, and the 1st coil part 22 and the 2nd coil part 23 are juxtaposed in the axis line L direction. The coil wire of the first coil portion 22 and the coil wire of the second coil portion 23 are connected in series, and the coil 24 is connected to the flexible circuit board 19.

  The ring-shaped magnet 13 is disposed so as to surround the coil 24 supported by the shaft 20 around the axis L, and is held in the case 2 by a leaf spring 17. The leaf spring 17 is a compression spring and urges the magnet 13 and the weight 15 in the direction of the axis L of the shaft 20. The magnet 13 in the power-off state is a partition portion between the inner peripheral surface 13 d of the magnet 13 and the bobbin 21. The first coil portion 22 and the second coil portion 23 are disposed across the first coil portion 22 and the second coil portion 23 so as to face each other.

  In such a linear vibration actuator 1, the magnet 13 and the shaft 20 constitute a magnetic circuit, and the coil 24 wound around the bobbin 21 is supported by the shaft 20 that forms a part of the magnetic circuit. Since it is arranged so as to be wound around the center, the coil 24 can be positioned by effectively using the shaft 20. That is, it is possible to position the coil 24 with reference to the shaft 20 erected in the case 2, whereby the position accuracy of the coil 24 in the case 2 can be easily increased, and the bobbin in the vibration actuator 1. 21 can be easily assembled.

  A clearance P1 between the outer peripheral surface 15c of the weight 15 and the peripheral wall 11b of the upper case portion 11 of the case 2 is smaller than a clearance P2 between the inner peripheral surface 13d of the magnet 13 and the outer peripheral surface 24a of the coil 24. If such a configuration is adopted, the outer peripheral surface 15c of the weight 15 and the peripheral wall 11b of the case 2 may collide with each other during a drop impact, but the outer peripheral surface 24a of the coil 24 and the inner peripheral surface 13d of the magnet 13 collide with each other. Therefore, the coil 24 is difficult to be disconnected due to a drop impact.

  The flange-shaped partition portion 21 d of the bobbin 21 protrudes from the outer peripheral surfaces 22 a and 23 a of the first coil portion 22 and the second coil portion 23. Such a configuration is intended to effectively use the partition portion 21d for partitioning the first coil portion 22 and the second coil portion 23 from each other. That is, since the free end of the partition portion 21d collides with the inner peripheral surface 13d of the magnet 13 at the time of a drop impact, a situation where the coil 24 and the magnet 13 do not collide occurs, and the coil 24 is disconnected by the drop impact. It becomes difficult. And this partition part 21d makes it easy to wind the coil wire of a different winding direction around the bobbin 21.

  In the weight 15, a concave portion 15 e for adjusting the mass of the weight 15 is formed in the upper plane portion 15 d orthogonal to the axis L. When such a configuration is adopted, a filling liquid (for example, a mixed liquid of tungsten powder and an adhesive) is inserted into the recess 15e provided in the weight 15 for vibration failure caused by individual differences of the weight 15 and the leaf spring 17. Thus, it is possible to easily adjust the vibration failure on the weight 15 side without adjusting the spring force of the leaf spring 17.

  When a voltage (for example, 5 V, 200 Hz) having a predetermined frequency is input (energized) from the power supply terminal 19c to the coil 24, the weight 15 vibrates in the direction of the axis L via the leaf spring 17, but at this time, the weight 15 is light. Even if it is too heavy or too heavy, there may occur a situation in which vibration cannot be generated in the case 2 or a desired vibration does not occur. As a correction measure in this case, the upper flat surface portion 15d of the weight 15 is formed with the concave portions 15e for adjusting the mass at equal intervals, and the above-described filling liquid is put therein to increase the mass of the weight 15 so that the coil 15 The weight 15 can be smoothly vibrated at the frequency input to 24. The correction measure in this case is not taken into consideration when the weight 15 is too heavy and no vibration is generated.

  The manufactured vibration actuator 1 is inspected with the upper case portion 11 removed, and the vibration actuator 1 that does not vibrate properly is corrected as described above.

  Both ends of the shaft 20 are press-fitted into the press-fitting holes 11 c of the upper case part 11 and the press-fitting holes 12 c of the lower case part 12, and the shaft 20 is erected at the center of the case 2 and is supported by such a shaft 20. On the flat end surface of the 21 flange portion 21b, hemispherical convex portions 26 are formed at equal intervals in the circumferential direction. Each of the convex portions 26 made of resin is pressed against the inner wall surface of the upper case portion 11 during assembly, so that the bobbin 21 can be firmly sandwiched between the upper case portion 11 and the lower case portion 12. As a result, the backlash of the bobbin 21 can be suppressed, abnormal noise can be prevented and drop impact resistance can be improved.

[Second Embodiment]
The linear vibration actuator 100 according to the second embodiment shown in FIG. 4 is different from the linear vibration actuator 1 according to the first embodiment in that a pair of ring-shaped planes facing each other in the magnet 13. The yokes 14 and 16 employed in the first embodiment are not fixed to the portions 13a and 13b. As for other configurations, the linear vibration actuator 100 according to the second embodiment has the same configuration as the linear vibration actuator 1 according to the first embodiment. The same reference numerals are given and description thereof is omitted.

  As shown in FIG. 5 (b), in the linear vibration actuator 1, when the magnet 13 is at the maximum movement position, that is, when the magnet 13 is at the end, for example, at the uppermost end, the yokes 14, 16 By adoption, the magnetic flux from the magnet 13 toward the shaft 20 tends to pass through the shortest path. This constitutes an efficient magnetic circuit. However, in the magnetic flux from the lower flat portion 13b of the magnet 13 toward the shaft 20, the magnetic flux passing through the first coil portion 22 is increased, thereby increasing the thrust F2 in the opposite direction to the thrust F1. Moreover, since the thrust F2 acts greatly as a brake for the thrust F1, the thrust of the magnet 13 directed in the direction of arrow A is reduced. This makes it difficult to obtain efficient vibration using the weight 15.

  On the other hand, as shown in FIG. 5A, in the linear vibration actuator 100, when the magnet 13 is at the maximum movement position, that is, when the magnet 13 is at the extreme end, for example, at the uppermost end, Since the yokes 14 and 16 are not employed, the magnetic flux from the magnet 13 toward the shaft 20 does not go through the shortest path as in the case where the yokes 14 and 16 exist. As a result, in the magnetic flux from the lower flat portion 13b of the magnet 13 toward the shaft 20, the magnetic flux passing through the first coil portion 22 is reduced, whereby the thrust F2 in the direction opposite to the thrust F1 is reduced by the vibration actuator 1. As a result, the thrust F2 is less likely to act as a brake for the thrust F1, so that the thrust of the magnet 13 in the direction of arrow A is increased. This makes it easy to obtain efficient vibration using the weight 15.

  In increasing the vibration efficiency of the linear vibration actuator 100, the influence of the distance R between the lower end 22b of the first coil part 22 and the lower flat part 13b of the magnet 13 is large, and the distance R increases. Indeed, in the magnetic flux from the lower flat portion 13 b of the magnet 13 toward the shaft 20, the magnetic flux passing through the first coil portion 22 is reduced, which increases the vibration efficiency using the weight 15. It is advantageous. Although not shown, the same applies to the case where the magnet 13 is at the lowermost end, and the weight becomes larger as the distance between the upper end 23b of the second coil portion 23 and the upper flat portion 13a of the magnet 13 becomes larger. It is advantageous to increase the vibration efficiency using the 15.

  In view of such a result, the thinner the magnet 13 is, the greater the disadvantage caused by the presence of the yokes 14, 16. Therefore, the magnet 13 is made thinner in order to increase the reciprocating distance of the magnet 13. In this case, it can be said that a type without the yokes 14 and 16 such as the linear vibration actuator 100 is advantageous.

  In FIG. 5, the weight 15 is omitted, but it goes without saying that the linear vibration actuators 1 and 100 have the weight 15.

  The present invention is not limited to the above-described embodiment, and various modifications as described below are possible without departing from the gist of the present invention.

  For example, a compression coil spring can be used as the biasing means instead of the leaf spring 17.

  DESCRIPTION OF SYMBOLS 1,100 ... Linear type vibration actuator, 2 ... Case, 13 ... Magnet, 14, 16 ... Yoke, 15 ... Weight, 15e ... Recessed part, 17 ... Leaf spring (biasing means), 20 ... Shaft, 21 ... Bobbin, 21d ... partition part, 22 ... first coil part, 23 ... second coil part, 24 ... coil, L ... axis, P1, P2 ... gap.

Claims (5)

In a linear type vibration actuator in which a magnet and a weight are fixed and the weight and the magnet are reciprocated by a coil in a case,
A shaft that is erected in the case and that forms a magnetic circuit made of a magnetic material,
The coil supported by the shaft;
The ring-shaped magnet disposed so as to surround the coil and the shaft;
The weight fixed to the magnet;
An urging means disposed in the case and urging the magnet and the weight in an axial direction of the shaft;
A linear vibration actuator characterized by comprising:   The ring-shaped weight is fixed to the outer peripheral surface of the magnet, and the gap between the outer peripheral surface of the weight and the case is smaller than the gap between the inner peripheral surface of the magnet and the outer peripheral surface of the coil. The linear vibration actuator according to claim 1.   A bobbin around which the coil is wound is disposed around the shaft, and the bobbin is provided with a partition portion projecting toward the inner peripheral surface of the magnet, and this partition portion is wound around the bobbin by reverse winding. 3. The linear vibration actuator according to claim 1, wherein the linear vibration actuator protrudes from outer peripheral surfaces of the rotated first coil portion and second coil portion.   The linear vibration actuator according to any one of claims 1 to 3, wherein a concave portion for mass adjustment of the weight is formed in a plane orthogonal to the axis in the weight. .   5. The magnet according to claim 1, wherein the magnet has a pair of ring-shaped plane portions facing each other, and a yoke is not fixed to each plane portion. Linear vibration actuator.

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