The present invention relates to a linear vibration motor.
A vibration motor (or “vibration actuator”) vibrates in accordance with a signal, such as an incoming call in a communication device, an alarm in any of a variety of electronic devices, or the like, to communicate to the user of the electronic device, or the user that touches can operating panel (a display panel) of the electronic device, that a signal has been produced, where such vibration motors are provided in a variety of electronic devices, such as in mobile information terminals.
Among the various forms of vibration motors that are under development, there are known linear vibration motors that are able to generate relatively large vibrations through linear reciprocating vibrations of a movable element. This linear vibration motor is provided with a structure wherein a coil is secured to a frame, and wherein an oscillator that is equipped with a weight on a magnet that produces a driving force (a thrusting force) in the axial direction, in cooperation with the coil, is supported by a magnet so as to enable vibration relative to the frame in the axial direction. In the explanation below, “up,” “down,” and “vertical” indicate the direction toward one side the direction toward the other side, in the direction of the vibration, regardless of the direction of the direction of the ground.
The linear vibration motor must be provided in a thin electronic device, and must apply a vibration effectively in response to a contact with the display panel (a touch panel/display panel), and so itself must be thin and must vibrate effectively along the direction of thickness. There is known prior art, set forth in Japanese Unexamined Patent Application Publication No. 2011-30403, below, as a linear vibration motor that satisfies both of these needs.
This prior art was structured from: a case, having a thin interior space; a stator that is provided with a coil that has a bottom end that is secured to a bracket that forms the bottom face of the case; and an oscillator that is made from a magnet, a yoke, and a weight, supported by a spring on the top face portion of the case, so as to be supported so as to enable vibrations up and down within the interior space of the case, wherein: the magnet is supported so as to enable vibration within a coil that is wound into a cylindrical shape around the direction of vibration, wherein a yoke is disposed encompassing the magnet beyond the top end of the coil, and a cylindrical magnetic gap is formed, corresponding to the coil, between the magnet and the yoke.
The thin linear vibration motor according to the prior art has the amplitude thereof limited by the vertical-direction of thickness of the case, and while an effective vibration is to be achieved through increasing the mass of the weight, if the volume of the weight in the interior space, which is constant within the case, is increased, then, given the structure, the diameter of the coil must be reduced, with a structure wherein, at the time of vibration, most of the coil is outside of the magnetic gap, and thus there is a problem in that vibration of the oscillator with a large thrusting force is not possible.
Moreover, the conventional linear vibration motor as described above is structured with the oscillator supported by a spring in a state wherein it is suspended on the top face portion of the case, where only the bottom end of the coil is supported on a bracket, and the yoke is disposed on the top end thereof, and thus the structure is one wherein the center part of the top face portion of the case is not supported. Because of this, extraneous vibrations are produced in the top face portion of the case, and thus there is a problem in that this produces noise.
The present invention is to respond to such problems, and the object thereof is to provide a linear vibration motor wherein the amplitude along the direction of thickness is limited, wherein a vibration can be produced with a large thrusting force while securing an adequate mass for the weight, and able to prevent the occurrence of noise through preventing extraneous vibrations in the top face portion of the case.
In order to achieve such an object, the linear vibration motor of the present invention is equipped with the following structures: a linear vibration motor comprising: a case having a top face portion; a bottom plate that faces the top face portion; a coil that is supported over the bottom plate and that is wound along a plane that is perpendicular to the bottom plate; a magnetic pole portion for producing a thrusting force in the vertical direction through an electric current that flows in the coil; a weight that vibrates together with the magnetic pole portion; and an elastic member for supporting the weight so as to enable vibration in the vertical direction. The linear vibration motor having the distinctive features set forth above enables the provision of a linear vibration motor wherein the amplitude along the direction of thickness is limited, wherein a vibration can be produced with a large thrusting force while securing an adequate mass for the weight. Moreover, this can prevent the occurrence of noise through preventing extraneous vibrations in the top face portion of the case.
An example according to the present invention will be explained below in reference to the drawings.
The case 2 is provided with, at least, a top face portion 2A. In the example in the illustration, the case 2 comprises a top face portion 2A and side face portions 2B that surround the top face portion 2A, having a thin vibration space S on the interior thereof. The bottom plate 3 is provided facing the top face portion 2A, and comprises a flat supporting face 3A for supporting the coil 4. In the example that is illustrated, the top face portion 2A and the bottom plate 3 have essentially circular planar shapes, but if there is no limitation thereto, and instead the top face portion 2A and the bottom plate 3 may be of arbitrary planar shapes, such as rectangles.
The coil 4 is supported on the bottom plate 3, and is wound along a plane that is perpendicular to the bottom plate 3. Through this, the axial direction of the windings of the coil 4 will be in a direction along the bottom plate 3 and the top face portion 2A. In this coil 4, as illustrated in
The top side outer peripheral surface 4b of the coil 4 can be secured to the top face portion 2A of the case 2. In this case, the height of the coil 4, including the height of the cradle portion 5, is set so as to match the spacing between the top face portion 2A of the case 2 and the supporting face 3A of the bottom plate 3. Securing the top side outer peripheral surface 4b of the coil 4 and the top face portion 2A of the case 2 causes the center portion of the top face portion 2A to be supported, and the coil 4 that is interposed between the top face portion 2A and the supporting face 3A of the bottom plate 3 serves as a supporting column, making enabling the prevention of extraneous vibrations in the top face portion 2A of the case 2, enabling the prevention of noise.
Moreover, the coil 4, which is wound along a plane that is perpendicular to the bottom plate 3 is provided with a top side straight portion 4L and a bottom side straight portion 4M that are essentially parallel along the top face portion 2A or the supporting face 3A of the bottom plate 3. The provision of the top side straight portion 4L and the bottom side straight portion 4M cause the coil 4 to be wound into an oval shape. The top side straight portion 4L and the bottom side straight portion 4M are coil parts wherein electrical currents flow in mutually opposite directions, and the lengths thereof can be set to be long, to enable the oscillator 20 to B vibrated up-in-down with a larger thrusting force, in cooperation with the magnetic pole portions 10, described below. Because here the top side straight portion 4L and the bottom side straight portion 4M can be set to be long, regardless of the thickness, even in the case of producing a thin linear vibration motor 1 wherein the spacing between the top face portion 2A of the case 2 and the supporting face 3A of the bottom plate 3 is narrow, this enables up-and-down vibration of the oscillator 20 with a large thrusting force in a thin linear vibration motor 1.
The weight 6 is disposed within a vibration space S, and has a thickness that is greater than the vertical spacing of the vibration space S, extending out of the vibration space, and has a larger planar shape that can be contained within the vibration space S, thereby making it possible to secure a weight that is adequate to achieve an effective vibration. The material for the weight 6 uses a material that is non-magnetic and that has a high specific gravity, where tungsten, for example, may be used.
The weight 6, which vibrates integrally with the magnetic pole portion 10, is formed with an opening portion 6A, in which the magnetic pole portion 10 is installed and through which the coil 4 passes in the vertical direction. The opening portion 6A is formed essentially rectangularly in the plan view, and is provided with a protruding portion 6A1 for maintaining a state wherein the yolks 13A and 13B of the magnetic pole portion 10, described above, are separated from each other.
The weight 6 is supported on the top face portion 2A of the case 2 by the elastic member 7 so as to enable up-and-down vibration thereof. The elastic member 7 is a leaf spring that has an outer peripheral portion 7A that is secured to the top face portion 2A side, an inner peripheral portion 7B that is secured to the top face of the weight 6, and an elastically deformable portion 7C that is formed between the outer peripheral portion 7A and the inner peripheral portion 7B. The weight 6 is elastically supported by the elastic member 7 in a state wherein the weight 6 is suspended from the top face portion 2A. Note that while, in the example that is illustrated, the weight 6 is supported by the elastic member 7 on the top face portion 2A side, it may instead be supported through an elastic member 7 on the supporting face 3A side of the bottom plate 3. In that case, the outer peripheral portion 7A of the elastic member 7 would be secured to the supporting face 3A, and the inner peripheral portion 7b would be secured to the bottom face of the weight 6.
As illustrated in
Additionally, the pair of first magnets 11A and 11B form a magnetic gap with the top side straight portion 4L of the coil 4 held therein, and the pair of second magnets 12A and 12B form a magnetic gap with the bottom side straight portion 4M of the coil 4 held therein. As illustrated in
Here thrusting forces that are always in the same direction will act on the top side straight portion 4L and on the bottom side straight portion 4M of the coiled 4, and thus the thrusting force that is produced by the first magnets 11A and 11B and the thrusting force that is produced by the second magnets 12A and 12B will add together, enabling the oscillator 20 to be vibrated with a large thrusting force. Moreover, the coil 4 is disposed so as to be wide between the top face portion 2A of the case 2 and the supporting face 3A of the bottom plate 3, making it possible to reduce extremely the top side straight portion 4L and the bottom side straight portion 4M from coming out of the magnetic gaps of the first magnets 11A and 11B and of the second magnets 12A and 12B, and enabling the oscillator 20 to be vibrated with a large thrusting force thereby.
As illustrated in
As described above, in the linear vibration motor 1 according to an example according to the present invention, an oscillator 20 that vibrates up-and-down is structured through joining together a weight 6 and a magnetic pole portion 10 that can produce a thrusting force in the vertical direction, through an electric current that flows in the coil 4, where the coil 4 that is wrapped along a plane that is perpendicular to the bottom plate 3 is supported over the bottom plate 3, enabling vibration with a large thrusting force, while securing an adequate weight for the weight 6, in a linear vibration motor wherein the amplitude along the direction of thickness is limited.
Moreover, the coil 4 is interposed between the top face portion 2A of the case 2 and the bottom plate 3, with the bottom side outer peripheral surface 4a of the coiled 4 secured to the bottom plate 3 side and the top side outer peripheral surface 4b of the coil 4 secured to the top face portion 2A side of the case 2, enabling the center portion of the top face portion 2A of the case 2 to be supported by the coil 4, enabling suppression of extraneous vibrations in the top face portion 2A, enabling prevention of noise. At this time, as illustrated in
While examples according to the present invention were described in detail above, referencing the drawings, the specific structures thereof are not limited to these examples, but rather design variations within a range that does not deviate from the spirit and intent of the present invention are also included in the present invention.
Number | Date | Country | Kind |
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2014-206787 | Oct 2014 | JP | national |
This is a U.S. national phase application under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2015/078197, filed Oct. 5, 2015, and claims benefit of priority to Japanese Patent Application No. 2014-206787, filed Oct. 7, 2014. The entire contents of these applications are hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/078197 | 10/5/2015 | WO | 00 |