JP4514273B2 - Multi-functional pronunciation body - Google Patents

Description

[0001]
The present invention relates to a structure of a multifunctional sounding body that responds to a plurality of frequency bands and outputs an acoustic frequency or even a low frequency vibration.
[0002]
[Prior art]
For example, an acoustic signal is output in response to an electrical input having an acoustic frequency of several hundreds to several kHz, and a vibration (vibration) output that can be felt in response to an electrical input having a low frequency of about 10 to 100 Hz is also performed. Multi-function sound generators are known. Since this is a single acoustic transducer, it can generate a plurality of types of signals, and is therefore highly effective as a means for reducing the size and cost of devices such as mobile phones. 4 and 5 show an outline of the structure of a conventional multi-function sound generator.
[0003]
FIG. 4 is a cross-sectional view schematically showing the structure of a multi-function sounding body as a first conventional example. Reference numeral 1 denotes a cover made of synthetic resin, which has a substantially box shape. Reference numeral 2 denotes a diaphragm for sound output. A peripheral portion is fixed to the cover 1 and the voice coil 3 is integrated. Reference numeral 5 denotes a cylindrical permanent magnet which is magnetized in the axial direction of the cylinder and is fixed to the center of a cylindrical cup-shaped yoke 7 made of a high magnetic permeability material. A top plate 6 is also a pole piece made of a high permeability material and is fixed to the upper end of the permanent magnet 5.
[0004]
The permanent magnet 5, the top plate 6 and the yoke 7 constitute a magnetic circuit. A suspension spring 8 is fixed to the yoke 7. The suspension spring 8 has a plurality of arm portions (shown only in a sectional view) extending toward the outside of the yoke 7, and the outer ends of the arm portions are fixed to the cover 1. Accordingly, the magnetic circuit is elastically suspended on the arm portion of the suspension spring 8 and can vibrate in the axial direction (vertical direction in the figure) as a unit. The ring-shaped portion of the outer periphery of the yoke 7 is an additional mass 9 that occupies the outside of the main part of the magnetic circuit and serves as an additional mass for sufficiently reducing the natural frequency of the magnetic circuit rather than as a magnetic flux path. Have. Therefore, the yoke 7 may be made of a different material and coupled.
[0005]
The magnetic flux generated by the permanent magnet 5 is concentrated in a ring-shaped magnetic gap between the peripheral side surface of the top plate 6 and the inner surface near the cup-shaped upper end of the yoke 7 to create a strong magnetic field. A voice coil 3 is inserted into the magnetic gap, and when a signal current having an acoustic frequency flows through the voice coil, the diaphragm 2 vibrates and emits sound. The cover 1 is fixed to the outer wall of a small electroacoustic apparatus or a circuit board (not shown).
[0006]
Due to such a configuration, when a drive current is input to the voice coil 3 from an external circuit (not shown), an electromagnetic force is relatively generated between the voice coil 3 and the magnetic circuit. When the drive current is an acoustic or audio frequency, the magnetic circuit does not respond because its natural frequency is much lower, and only the diaphragm 2 vibrates and outputs sound. However, if the drive current has a low frequency close to the natural frequency of the magnetic circuit, the diaphragm 3 hardly responds, and the magnetic circuit resonates and vibrates in the axial direction with a large amplitude. Then, in an environment where sound is disliked, or in an environment where the noise is high and the sound signal is inappropriate, a signal is generated that is silent and can be experienced.
[0007]
In general, a magnetic circuit always has a leakage magnetic flux, and it is not preferable that the magnetic flux reaches far away because it affects other parts and devices. In FIG. 4, a ring-shaped groove 11 provided in the yoke 7 is provided to prevent leakage of magnetic flux. That is, since the inside of the groove 11 provided in the high magnetic permeability material has high magnetic resistance, the magnetic flux that makes a round with the permanent magnet 5 → the top plate 6 → the magnetic gap → the upper end of the yoke 7 → the lower end of the yoke 7 → the permanent magnet 5 is This portion is rarely exceeded, leakage to the outside is reduced, and the magnetic flux is concentrated in a necessary magnetic gap.
[0008]
FIG. 5 is a cross-sectional view schematically showing the structure of a multi-function sounding body as a second conventional example. The structure is almost the same as that of the first conventional example of FIG. 4, and the reference numerals assigned to the respective parts are also common. The difference from the first conventional example is a structure for preventing leakage magnetic flux. In the second conventional example, the magnetic shield 10 is made of a material having a higher magnetic permeability than the material of the yoke 7 instead of the groove. Close up. Most of the magnetic flux generated from the permanent magnet passes through the inside of the magnetic shielding ring 10 having a low magnetic resistance, and the ratio of the leakage magnetic flux becomes small.
[0009]
[Problems to be solved by the invention]
Each of the above conventional examples employs an internal magnet type structure in which the yoke surrounds the permanent magnet at the central shaft portion. On the other hand, there is an outer magnet type structure in which the permanent magnet is ring-shaped and the main part of the magnetic flux generated by the permanent magnet is concentrated in the magnetic gap inside the permanent magnet ring. Try to adopt the configuration. The outer magnet type structure can easily make the volume of the permanent magnet larger than that of the inner magnet type, and can use a large magnetic energy. If the volume of the permanent magnet is reduced, there is an advantage that a relatively thin magnetic circuit can be designed. However, since the permanent magnet is on the outside, the magnetic flux leakage to the outside tends to be somewhat large, and it is necessary to effectively suppress this. However, a highly effective magnetic flux leakage prevention structure for the outer magnet type structure has not yet been proposed. Not.
[0010]
An object of the present invention is to provide a multi-function sounding body adopting an outer magnet type structure that can effectively reduce the leakage magnetic flux to the outside and sufficiently exhibit the advantages of the outer magnet type. It is.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the multi-function sounding body of the present invention has the following characteristics.
(1) A cover, a diaphragm that is supported by the cover and vibrates by receiving an electromagnetic force of an acoustic frequency, and a relatively low-frequency vibration system that is elastically supported by the cover by an elastic member is formed on the diaphragm. On the other hand, it comprises a magnetic circuit having a relatively large mass including a permanent magnet that provides a magnetic field for generating the electromagnetic force, and the diaphragm or the magnetic circuit mainly corresponds to an electrical input of a plurality of frequency bands. In the multifunctional sounding body that vibrates in response to
The permanent magnet has a ring shape to form the magnetic field inside thereof, and the elastic member is formed of a suspension spring having an outer portion fixed to the cover and an inner portion fixed to the magnetic circuit . In order to reduce leakage of magnetic flux to the outside, the cover disposed outside the permanent magnet with a non-fixed portion of the suspension spring is formed of a material obtained by mixing a powder of high permeability material with synthetic resin. thing.
[0012]
The multi-function sounding body of the present invention may further include at least one of the following features.
(2) The suspension spring is composed of an upper suspension spring and a lower suspension spring, which are two leaf springs arranged in parallel to the axis direction of the multi-function sounding body, and the outer portion of each suspension spring is the shaft. Are fixed to the upper cover and the lower cover constituting the cover, respectively, and the planar shapes on the inner surface side of the upper cover and the lower cover toward the axis are substantially the same, It is arranged to keep substantially the same distance from the outer periphery of the permanent magnet.
(3) the high-permeability material is that it is a soft ferrite.
[0013]
(4) The elastic member is insert-molded in the cover material.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of a multifunctional sound producing body as an example of an embodiment of the present invention. Parts having common functions with those already described with reference to FIGS. 5 and 6 are denoted by the same symbols and names, and redundant description is omitted. The following parts are mainly different from the conventional example.
(1) The permanent magnet 5 is not cylindrical but ring-shaped (magnetization is in the thickness direction), occupies the outside of the magnetic circuit, and has a so-called outer magnet type structure. Accordingly, in the pole piece 4 corresponding to the yoke 7 of the conventional example, the high magnetic permeability soft magnetic part is not the outer peripheral part but the core part as shown in the perspective view of FIG. Also, the top plate 6 has a ring shape unlike the conventional example.
[0015]
(2) The synthetic resin cover 1 has two upper and lower bodies, and the upper cover spring 8a and the lower suspension spring 8b, which are elastic members that elastically support the magnetic circuit, are integrally formed on the upper cover 1a and the lower cover 1b by an insert mold. Being made. This structure and the processing method therefor are the eyes of the present invention. Moreover, the planar shape of the cover is not square but circular. The upper and lower covers are joined together when assembling the multi-function sounding body (the upper and lower arms are 90 ° different). Inside, the magnetic circuit is elastically suspended by the arms of the upper and lower suspension springs as in the prior art.
[0016]
(3) In the outer magnet type structure, a strong gap magnetic flux can be obtained by using a large-volume permanent magnet, but there is a tendency that a relatively large amount of magnetic flux leaks from the permanent magnet to the outside. Therefore, a high magnetic permeability material, for example, soft ferrite powder is mixed in the cover located slightly outside the outer periphery of the permanent magnet 5 to give high permeability, and the leakage flux is collected in the cover and leaked to the outside. To reduce as much as possible.
[0017]
FIG. 2A is a plan view of the upper cover in the above-described embodiment of the present invention, and FIG. 2B is a plan view of the lower cover, both showing a state where the insert molding of the suspension spring is completed. . Each of the upper suspension spring 8a and the lower suspension spring 8b has a flat plate shape and has concentric ring portions on the inner side and the outer side, and both the rings are connected by a pair of substantially semicircular arc-shaped arm portions arranged symmetrically. Yes. As shown in FIG. 1, the outer ring is molded in the cover, the lower suspension spring 8b is on the stepped portion on the lower surface of the pole piece 4, and the upper suspension spring 8a is on the stepped portion on the upper surface of the top plate 6. Press fit.
[0018]
Both the upper cover 1a and the lower cover 1b are substantially ring-shaped, but the upper cover 1a has a terminal portion 1f that is a rectangular protrusion. Two terminal pins 1g are planted in this portion. These are connected to lead wires from both ends of the voice coil 3 when assembling the multi-function sound generator. Further, a part of the upper suspension spring 8a extends through the terminal portion 1f and becomes the ground terminal 8d. A diaphragm 2 with concentric pleats is bonded to the upper portion of the upper cover 1a at the outer periphery thereof.
[0010]
Although an example of the embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to this embodiment. For example, not only the material, ratio, particle size and shape of the high permeability material mixed into the resin material in the cover, but also the shape of the cover, the shape of the suspension spring, the number of arms and the number, the shape of the diaphragm, the shape of the permanent magnet, the pole piece The shape, the shape of the top plate, the provision of additional mass, the shape of other details, the addition of other members, or the material of each part can be variously changed.
[0020]
【The invention's effect】
(1) In the present invention, since the material of the cover located outside the ring-shaped permanent magnet is given high magnetic permeability, even in a simple structure and a small size, even in an external magnetic structure. There is an effect that the leakage magnetic flux can be sufficiently reduced.
[0021]
(2) Furthermore, an effective magnetic-shielding structure was realized by using the material mixed in the cover as soft ferrite.
[0022]
(3) Since the elastic member for supporting the magnetic circuit is insert-molded in the cover having high permeability, a magnetic shielding effect is obtained by a simple structure and the magnetic circuit vibrating in the multifunctional sounding body There is an effect that accurate positioning can be achieved simultaneously.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multifunctional sounding body as an example of an embodiment of the present invention.
2A is a plan view of an upper cover in an example of an embodiment of the present invention, and FIG. 2B is a plan view of a lower cover in the same example.
FIG. 3 is a perspective view of a pole piece in an example of an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a first conventional example of a multifunctional sounding body.
FIG. 5 is a cross-sectional view of a second conventional example of a multi-function sounding body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cover 1a Upper cover 1b Lower cover 1f Terminal part 1g Terminal pin 2 Diaphragm 3 Voice coil 4 Pole piece 5 Permanent magnet 6 Top plate 7 Yoke 8a Upper suspension spring 8b Lower suspension spring 8d Ground terminal 9 Additional mass 10 Magnetic shield ring 11 Groove

Claims (4)

A cover, a diaphragm that is supported by the cover and vibrates by receiving an electromagnetic force of an acoustic frequency, and constitutes a relatively low-frequency vibration system that is elastically supported by the cover by an elastic member; The magnetic circuit includes a permanent magnet that provides a magnetic field for generating electromagnetic force and has a relatively large mass. The diaphragm or the magnetic circuit mainly responds to electrical inputs in a plurality of frequency bands. In a multifunctional sounding body that vibrates
The permanent magnet has a ring shape and forms the magnetic field inside thereof, and the elastic member is formed of a suspension spring having an outer portion fixed to the cover and an inner portion fixed to the magnetic circuit . In order to reduce the leakage of magnetic flux to the outside, the cover disposed outside the permanent magnet with the non-fixed portion of the suspension spring interposed therebetween is formed of a material obtained by mixing high permeability material powder with synthetic resin. Multi-function sound generator characterized by that. The suspension spring includes an upper suspension spring and a lower suspension spring that are two leaf springs arranged in parallel to the direction of the axis of the multifunctional sounding body, and the outer portion of each suspension spring is in the direction of the axis. The upper cover and the lower cover that overlap each other are fixed to the upper cover and the lower cover, respectively, and the planar shapes on the inner surface side toward the shaft of the upper cover and the lower cover are substantially the same, both of which are the permanent magnets 2. The multi-function sounding body according to claim 1, wherein the multi-functional sounding body is disposed at substantially the same distance from the outer periphery of the sounding member. The multifunctional sounding body according to claim 1 or 2 , wherein the high magnetic permeability material is soft ferrite. The multifunctional sounding body according to any one of claims 1 to 3, wherein the elastic member is insert-molded in the cover material.

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