JP4244687B2 - Linear vibration actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear vibration actuator mounted on various portable devices such as a mobile phone, a PDA, a game device, a watch, and an information portable terminal.
[0002]
[Prior art]
Conventionally, as the above linear vibration actuator, a magnetic circuit having a magnetic gap is formed by a magnet and a magnetic yoke, and a moving coil is arranged as a movable element in the magnetic gap, or a magnet, a magnetic yoke, and this magnetic yoke are installed. A magnetic circuit having a magnetic gap is formed with the driving coil, and a magnetic armature as a movable element, that is, a magnetic piece is disposed in the magnetic gap. The magnetic circuit has a high compliance portion on a rigid support. There is a structure in which a movable element is fixed to this support body, supported by a damper. When a low-frequency drive current lower than the audio frequency is applied to the coil, the magnetic circuit is flexibly supported by a high-compliance spring formed on the damper in a spiral shape, so it vibrates with this low-frequency signal and passes through the damper. Thus, the low-frequency vibration is transmitted to the support body, and the vibration can be transmitted to the human body via the support body. When an AC drive current having a sound frequency is applied to the coil, the magnetic circuit is supported by the high compliance portion of the damper, so that the movable element, not the magnetic circuit, vibrates at the sound frequency, and the vibration is transmitted to the support. The thin plate or diaphragm coupled to the oscillates and generates an audible sound. In other words, a linear vibration actuator has been proposed that aims to generate audible frequency vibration and bodily sensation vibration with a single mechanism (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-316268 A (page 2-5, FIG. 1)
[0004]
[Problems to be solved by the invention]
In order to meet the recent demand for smaller and thinner portable devices, it is necessary to further reduce the size and thickness of linear vibration actuators. In order to reduce the thickness, it is difficult to ensure the vibration amplitude (stroke), so it is necessary to increase the mass of the movable part. However, the linear vibration actuator disclosed in Patent Document 1 is supported by a support through a damper having a high compliance portion so that an audible frequency vibration and a sensory vibration can be generated by one mechanism. Since the magnetic circuit itself becomes a movable part when low-frequency body vibration is generated, the vibration direction tends to be unstable with respect to the support, and there is a restriction on increasing the weight of the movable part. It had the problem that it was difficult to generate. In order to solve this problem, the present invention has developed a linear vibration motor that can obtain sufficient body vibration while being small and thin by specializing in the generation of body vibration. Therefore, first, a configuration in which a part of the magnetic circuit is a movable part and the rest is a fixed part, and both ends in the vibration direction of the movable part are supported by an elastic body with respect to the fixed part, so that The direction was surely settled. In addition, in order to increase the mass of the movable part, a mover is constituted by a ring-shaped core and a permanent magnet fixed to the inner peripheral side thereof, and a magnet facing the permanent magnet via a gap is formed on the fixed part side. The rest of the circuit was placed.
[0005]
Since the vibration direction with respect to the fixed portion of the movable portion is reliably determined by the above configuration, the gap between the magnetic circuit and the permanent magnet can be reduced, so that an efficient magnetic circuit can be configured. The coil is wound around a core different from the core constituting the remaining part of the magnetic circuit on the fixed part side.
[0006]
The configuration will be described with reference to FIGS. 7A and 7B. FIG. 7A is a plan view of the linear vibration actuator at the initial stage of development (the cover is seen through), and FIG. 7B is a coaxial sectional view. A ring-shaped first core 43, a mover 41 having a permanent magnet 42 fixed to the inner peripheral side of the first core 43, and an inner peripheral side of the permanent magnet 42, facing each other via a gap, A stator 46 having a second core 45 having an axially symmetric shape with a cut-out cross section and a coil portion 44 wound around the central portion of the second core; A plate spring 47 having the second core 45 of the stator 46 and the other end fixed to the first core 43 of the mover 41 is provided above and below the mover 41, and the mover 41 is fixed to the stator 46 by the plate spring 47. Is supported so as to be displaceable in the axial direction. The permanent magnet 42 on the inner circumference side of the mover 41 is magnetized to a single pole so that the inner circumference side has the same pole and is different from the outer circumference side. For example, the inner peripheral side is magnetized to the N pole and the outer peripheral side is magnetized to the S pole. The mover 41 vibrates up and down in accordance with the magnetic flux generated when an alternating current or pulse current is applied to the coil portion 44, and the kinetic energy of the mover 41 is extracted as vibration.
[0007]
At the initial stage of development, the leaf spring 47 has a shape having four arms 472 from its center to the outer ring part 471 as shown in FIG. An annular portion 471 is fixed to the first core 43 of the mover 41. However, in order to increase the perceived vibration level, it has been found that it is not sufficient to increase the mass of the mover 41, and it is necessary to increase the vibration amplitude, that is, the stroke of the mover 41. It was necessary to lengthen the arm portion 472 of the spring 47. Therefore, as shown in FIG. 8, the leaf spring 56 is concentric from the outer periphery toward the center of the stator and is concentric and has an arc-shaped outer arm 561, inner arm 562, and outer arm 561. It tried to lengthen the effective length of a spring and enlarge a stroke by making it the structure provided with the connection part 563 of the substantially U shape which connects the arm part 562 of an inner peripheral side. Since the spring having this configuration can form a plurality of arc-shaped arm portions, it is a very effective shape for extending the effective length of the spring. However, portable devices are highly likely to fall due to handling, and resistance to this drop impact is required. In the shape of the leaf spring 56 shown in FIG. 8, the stress concentrates on the connecting portion 563 between the outer peripheral arm portion 561 and the inner peripheral arm portion 562, and there are problems such as deterioration of spring characteristics and breakage of the spring. It was difficult to obtain a small size, a large stroke, that is, a large vibration.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention includes a stator and a ring-shaped mover, and plate springs having one end fixed to the stator and the other end fixed to the mover on both upper and lower sides of the mover. The leaf spring has a configuration in which the mover is supported to be axially displaceable with respect to the stator, and the leaf spring is concentric with respect to the center of the stator and has an arc-shaped arm portion. Are formed from the outer peripheral side of the leaf spring toward the center of the stator, and the arm portion on the outer peripheral side of the arm portion and the arm portion on the inner peripheral side are connected by a substantially U-shaped connecting portion. The gap width of the U-shaped bottom portion of the substantially U-shaped connecting portion is formed to be greater than the gap width between the outer peripheral arm portion and the inner peripheral arm portion, or the substantially U-shaped The width of the U-shaped bottom portion of the connecting portion is determined by any of the width of the outer peripheral arm portion, the inner peripheral arm portion, and the substantially U-shaped connecting portion. A linear vibration actuator which is larger.
[0009]
With this configuration, not only can the mass of the mover be increased and the vibration stroke of the mover be increased, but also local stress concentration of the leaf spring can be mitigated, spring characteristics can be degraded, and the spring can break. It is possible to provide a small, thin and high-performance linear vibration actuator that has been solved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention includes a ring-shaped first core, a mover having a permanent magnet fixed to the inner peripheral side of the first core, and a gap on the inner peripheral side of the permanent magnet. It has a stator that is a coil portion wound in such a manner that it is disposed oppositely and has a cross-sectionally axisymmetrically shaped second core having a notch at the center of the outer periphery and a central portion of the second core. A leaf spring having one end fixed to the stator and the other end fixed to the mover is disposed on the inner side, and the mover is supported by the plate spring so as to be displaceable in the axial direction with respect to the stator. A linear vibration actuator having a configuration, wherein the leaf spring is formed with a plurality of concentric and arc-shaped arm portions from the outer periphery of the leaf spring toward the center of the stator. The U-shaped bottom gap width of the connecting portion of the arm portion is set to be equal to the inner peripheral arm portion. Formed above the gap width between the arms of the side, the line connecting the center of the fixed portion and the second core of the arm tip and the first core of the arc shape of the outer peripheral side of the leaf spring, It has the 2nd arm part formed toward the fixed part of a leaf | plate spring and a 2nd core connected by the arc-shaped arm part of the inner peripheral side of a leaf | plate spring, and a 2nd connection part, It is characterized by the above-mentioned. It is a linear vibration actuator.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the gap width between the outer peripheral side arm portion and the inner peripheral side arm portion is set to the outer peripheral side and inner peripheral side. The linear vibration actuator is characterized in that it is formed larger than both the width of the arm portion and the width of the connecting portion.
[0013]
The invention according to claim 3 of the present invention is the invention described in claim 1 or claim 2 , wherein the outer peripheral side arc-shaped arm portion and the inner peripheral side arc-shaped arm portion of the leaf spring are provided. A plurality of support pieces each including a first connection portion, a second connection portion, and a second arm portion having a substantially U shape are formed in the circumferential direction in point symmetry with respect to the center of the leaf spring.
[0014]
According to a fourth aspect of the present invention, in the first or second aspect of the invention, the arc-shaped arm portion on the outer peripheral side and the arc-shaped arm portion on the inner peripheral side of the leaf spring are substantially the same. A support piece formed of a U-shaped first connection portion, a second connection portion, and a second arm portion is formed by concentrically forming the support pieces in three circumferential directions with respect to the center of the leaf spring. .
[0015]
According to a fifth aspect of the present invention, the first core is a stator and the second core is a mover according to the first to fourth aspects.
[0016]
According to a sixth aspect of the present invention, the linear vibration actuator according to the first to fifth aspects is mounted on a portable device, and a small and high-performance portable device can be realized.
[0017]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
Example 1
FIGS. 1A and 1B show the configuration of an embodiment of the linear vibration actuator according to the present invention. FIG. 1A is a plan view of the linear vibration actuator in this embodiment (the cover is seen through), and FIG. 1B is a coaxial sectional view.
[0019]
A movable element 1 composed of a ring-shaped first core 3 and a permanent magnet 2 fixed on the inside thereof, and an axially symmetric second core 5 having a cross-sectional shape with a gap in the inside via a gap. The stator 6 having the coil portion 4 wound so as to surround the central portion is supported from both the upper and lower sides of the mover 1 by leaf springs 7 that are elastic bodies so as to be displaceable in the axial direction. . Each of the leaf springs 7 is fixed to the stator 6 at one end and the mover 1 at the other end. The permanent magnet 2 inside the mover 1 is magnetized to a single pole so that the inner circumference side has the same polarity and the outer circumference side has a different polarity. (For example, the inner circumference side is the N pole and the outer circumference side is the S pole.) Then, the mover 1 vibrates up and down in accordance with the magnetic flux generated when an alternating current or pulse current is applied to the coil portion 4, and the kinetic energy of the mover 1 is vibrated. Take out as.
[0020]
As shown in FIG. 1A, the leaf spring 7 of the present embodiment has a concentric arc-shaped outer peripheral arm portion 71 and an inner peripheral arm portion 72 from the outer peripheral portion toward the center of the stator 6. And a substantially U-shaped connecting portion 73 for connecting the outer peripheral arm portion 71 and the inner peripheral arm portion 72, and the central portion of the leaf spring 7 is positioned on the stator 6 and the outer periphery of the leaf spring 7. The arm portion distal end is fixed to the mover 1, and the mover 1 is supported so as to be displaceable in the axial direction.
[0021]
With this configuration, since the effective length of the leaf spring 7 can be increased, the vibration amplitude of the mover 1 can be increased, and a small amount of vibration can be obtained. However, when deformed in the axial direction, the spring part is deformed the most at the outer peripheral arm part 71 having a narrow width, the spring vibrates the arm part, and similarly the inner peripheral arm part 72 is also displaced in the displacement direction. In order to exercise, the connecting portion 73 between the arm portion 71 on the outer peripheral side and the arm portion 72 on the inner peripheral side serves as a fulcrum for the exercise, and stress is concentrated locally. In this way, if the stress is excessively concentrated at one location of the spring, the fracture starts from that location, and in the worst case, the spring is broken. Therefore, in order to avoid stress concentration without reducing the amount of vibration, it is sufficient that the stiffness is not significantly changed locally. Therefore, the stress concentration of the connecting portion 73 can be alleviated by appropriately reducing the width of the spring of the connecting portion 73. Therefore, as a result of experimental determination, as shown in FIG. 2, the width a1 of the substantially U-shaped connecting portion 73 is formed to be equal to or larger than the gap width d1 between the outer peripheral arm portion and the inner peripheral arm portion. For example, it was found that the stress concentration of the connecting portion 73 can be distributed to the outer peripheral arm portion 71 or the inner peripheral arm portion 72, and the stress concentration of the connecting portion 73 can be reduced. Therefore, it is possible to provide a small and high-performance linear vibration actuator that solves the problems such as deterioration of the spring characteristics and breakage of the spring without reducing the vibration amount.
[0022]
(Example 2)
FIG. 3 shows the configuration of the linear vibration actuator according to an embodiment of the present invention (plan view, cover is transparent).
[0023]
The configuration of the basic member of the actuator is the same as that of the first embodiment.
[0024]
In this configuration, in order to avoid stress concentration without reducing the vibration amount, it is only necessary that the stress can be distributed to other regions where the stress is not concentrated. In this embodiment, since stress is concentrated on the connecting portion 73 between the outer peripheral arm portion 71 and the inner peripheral arm portion 72, the stress is applied to the outer peripheral arm portion 71 or the inner peripheral portion. What is necessary is just to disperse | distribute to the arm part 72 of a side to some extent. Therefore, the width b2 of the arm portion 72 on the inner peripheral side and the width c2 of the arm portion 71 on the outer peripheral side are set to be equal to those of the slit portion between the arm portion 71 on the outer peripheral side of the leaf spring 7 and the arm portion 72 on the inner peripheral side. It was formed larger than the width a2. With this configuration, the stress concentrated on the connection portion 73 between the outer arm portion 71 and the inner arm portion 71 of the leaf spring is distributed to the thinner outer arm portion 71 and inner arm portion 72. The local maximum stress of the connecting portion 73 was relaxed, and the stress resistance limit value could be improved.
[0025]
In general, the width a2 of the slit portion between the arm portion 71 on the outer peripheral side of the leaf spring 7 and the arm portion 72 on the inner peripheral side, the width b2 of the arm portion 72 on the inner peripheral side, and the arm portion 71 on the outer peripheral side. It was found that the stress concentration at the connection portion 73 can be alleviated if it is formed larger than the width c2. The result of confirming the effect experimentally is shown in FIG.
[0026]
Therefore, it is possible to provide a small and high-performance linear vibration actuator that solves the problems such as deterioration of the spring characteristics and breakage of the spring without reducing the vibration amount.
[0027]
In this embodiment, with respect to the outer diameter φ7.4 mm of the leaf spring, the movable element has an amplitude of ± 0.8 mm and achieves a vibration of 1 G or more.
[0028]
(Example 3)
The second embodiment of the present invention has the same configuration as that of the first embodiment, but has a different leaf spring shape. 5 and 6 are plan views of the leaf springs used in the second embodiment. The leaf spring 7 of the present embodiment includes an arc-shaped arm portion on the outer peripheral portion of the leaf spring, an arc-shaped arm portion on the inner peripheral side, a first connection portion 73 and a second connection portion 74 having a substantially U shape. A plurality of support pieces made of the second arm portion 75 are formed in a circumferential direction with point symmetry with respect to the center of the leaf spring, and the center portion of the leaf spring is located on the outer periphery of the leaf spring. The arm tip is fixed to the mover so that the mover can be displaced in the axial direction.
[0029]
In FIG. 5, the radial rigidity of the leaf spring is increased, and the coaxiality of the mover and the stator can be improved. Further, since the width a3 of the slit portion between the inner peripheral side arm portion and the outer peripheral side arm portion is formed larger than the widths b3 and c3 of the respective arm portions of the leaf spring, no stress is concentrated locally on the leaf spring. Therefore, it is possible to provide a high-performance linear vibration actuator that is small and thin and generates a large stroke, that is, a large vibration.
[0030]
Similarly, FIG. 6 shows an example in which the leaf spring support pieces are four. Since the width a4 of the slit part between the arm part on the inner peripheral side and the arm part on the outer peripheral side is formed larger than the widths b4 and c4 of the arm part of the leaf spring, stress is not concentrated locally on the leaf spring. It is possible to provide a high-performance linear vibration actuator that is small and thin and generates a large stroke, that is, a large vibration.
[0031]
Even when the movable part and the fixed part of the linear vibration actuator according to the first and second embodiments are reversed, the both ends in the vibration direction of the mover are held by leaf springs, and the above-described leaf spring shape is used. It is clear that the same effect as described above can be obtained in
[0032]
【The invention's effect】
The present invention can not only increase the mass of the mover and increase the vibration stroke of the mover, but also reduce the local stress concentration of the leaf spring, thereby deteriorating the spring characteristics, Therefore, it is possible to provide a high-performance linear vibration actuator that is small and thin and has a large vibration and solves the problem of breakage.
[0033]
In addition, by mounting the linear vibration actuator of the present invention, it is possible to realize a small and high-performance portable device such as a mobile phone, a PDA, a game, a watch, and an information device terminal.
[Brief description of the drawings]
FIG. 1A is a plan view of a linear vibration actuator according to a first embodiment of the present invention. FIG. 2B is an axial sectional view of the linear vibration actuator according to the first embodiment of the present invention. FIG. 3 is a plan view of the linear vibration actuator according to the second embodiment of the present invention. FIG. 4 is a stress characteristic diagram illustrating the effect of the second embodiment of the present invention. FIG. 6 is a plan view of the plate spring of the linear vibration actuator according to the third embodiment of the present invention. FIG. 7A is a plan view of the linear vibration actuator at the initial stage of development of the present invention. [Fig. 8] Plan view of the linear vibration actuator under development of the present invention [Fig. 8]
1, 41 Movable element 2, 42 Permanent magnet 3, 43 First core 4, 44 Coil portion 5, 45 Second core 6, 46 Stator 7, 47, 56 Leaf spring 8 Cover 71, 561 Arm on outer peripheral side Portions 72 and 562 Inner circumferential arms 73 and 563 U-shaped connecting portion (first connecting portion)
74 substantially U-shaped connecting part (second connecting part)
75 Second arm portion 471 Annular portion 472 Four arm portions

Claims (6)

A ring-shaped first core, a mover in which a permanent magnet is fixed to the inner peripheral side of the first core, and an inner peripheral side of the permanent magnet are opposed to each other via a gap, and a notch is formed in a central portion of the outer periphery. Having a stator that is a coil portion wound around a second core of a cross-sectional shape and an axially symmetric shape and a central portion of the second core, and one end on the inner side, A linear vibration actuator having a configuration in which a plate spring having the other end fixed to the mover is disposed, and the mover is supported by the plate spring so as to be axially displaceable with respect to the stator, The leaf spring is formed with a plurality of arc-shaped arm portions concentric with the center of the stator from the outer peripheral portion of the leaf spring toward the center of the stator, and a U-shaped bottom gap in the connecting portion of the arm portion The width is equal to or greater than the gap width between the outer arm portion and the inner arm portion. None,
The arc-shaped arm portion on the inner peripheral side of the leaf spring and the second portion are arranged on a line connecting the tip of the arc-shaped arm portion on the outer peripheral side of the leaf spring, the fixing portion of the first core and the center of the second core. A linear vibration actuator characterized in that it has a second arm portion that is connected toward the fixed portion between the leaf spring and the second core by being connected by the connecting portion . A ring-shaped first core, a mover in which a permanent magnet is fixed to the inner peripheral side of the first core, and an inner peripheral side of the permanent magnet are opposed to each other via a gap, and a notch is formed in a central portion of the outer periphery. Having a stator that is a coil portion wound around a second core of a cross-sectional shape and an axially symmetric shape and a central portion of the second core, and one end on the inner side, A linear vibration actuator having a configuration in which a plate spring having the other end fixed to the mover is disposed, and the mover is supported by the plate spring so as to be axially displaceable with respect to the stator, The leaf spring is formed with a plurality of arc-shaped arm portions concentric with the center of the stator from the outer peripheral portion of the leaf spring toward the center of the stator, and the U-shaped bottom gap width of the arm portion is set to the outer periphery. The width of the arm portion on the side, the width of the arm portion on the inner peripheral side, and a substantially U shape Than any of the width of the connection portion is larger,
The arc-shaped arm portion on the inner peripheral side of the leaf spring and the second portion are arranged on a line connecting the tip of the arc-shaped arm portion on the outer peripheral side of the leaf spring, the fixing portion of the first core and the center of the second core. A linear vibration actuator characterized in that it has a second arm portion that is connected toward the fixed portion between the leaf spring and the second core by being connected by the connecting portion . An arc-shaped arm portion on the outer peripheral side of the leaf spring, an arc-shaped arm portion on the inner peripheral side, a substantially U-shaped first connection portion, a second connection portion, and a support piece composed of a second arm portion, claim 1 or claim 2 linear vibration actuator, wherein the forming a plurality circumferentially point symmetry with respect to the center of the leaf spring. An arc-shaped arm portion on the outer peripheral side of the leaf spring, an arc-shaped arm portion on the inner peripheral side, a substantially U-shaped first connection portion, a second connection portion, and a support piece composed of a second arm portion, claim 1 or claim 2 linear vibration actuator, wherein the support piece in the circumferential direction concentrically with respect to the center of the leaf spring is three shapes. The stator of the first core, the linear vibration actuator according to claim 1 to 4, wherein in that the second core to the movable element. It claims 1 to portable devices with linear vibration actuator 5 according.

Images