JP4341939B2 - Multi-functional pronunciation body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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. FIG. 3 shows an outline of the structure of the conventional multi-function sounding body.
[0003]
FIG. 3 is a schematic cross-sectional view of a conventional multi-function sounding body in which each main part has a substantially cylindrical shape. Reference numeral 1 denotes a casing made of a synthetic resin and having a substantially cylindrical shape. 2 is a diaphragm for sound output, and a drive coil 3 is integrated. Reference numeral 4 denotes a magnetic circuit, and a yoke 4a, a permanent magnet 4b, and a circular flat pole piece (also referred to as a top plate) 4c concentrate a driving magnetic field in the magnetic gap 4d. The magnetic circuit 4 is coupled to the housing 1 by a support spring 5. 4e is a cylindrical additional mass, which is fixed to the magnetic circuit 4 and serves as a weight for sufficiently reducing the natural frequency, and is included in the mass of the magnetic circuit 4 to increase the sensibility of low-frequency vibration in the audible range. The natural frequency of the magnetic circuit is about 10 to several tens Hz. The upper surface or the lower surface of the housing 1 is fixed to the outer wall or circuit board (not shown) of the small electroacoustic apparatus.
[0004]
Due to such a configuration, when a drive current is input to the drive coil 3 from an external circuit (not shown), an electromagnetic force is generated relative to the magnetic circuit 4. If the drive current is an acoustic or audio frequency, the magnetic circuit 4 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 4, the diaphragm 3 hardly responds, and the magnetic circuit 4 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.
[0005]
[Problems to be solved by the invention]
When trying to improve the sensibility at low frequencies below the audible frequency, it is important that the vibration mass is as large as possible. Therefore, in the prior art, as shown in FIG. 3, a ring-shaped additional mass 4e is fitted into the yoke 4a to increase the vibration mass. However, this additional mass is independent of the magnetic properties of the sounding body. Anyway, if the mass of the magnetic circuit is increased, the mass of the components necessary for the magnetic circuit should be increased, and even if the mass increase is slight, the magnetic characteristics of the sounding body should be positively added. It is desirable. In view of the demand for downsizing and thinning of the sound generator, and hence the acoustic electronic device in which the sound generator is incorporated, it is desirable that the increased mass be disposed in a space that has not been used effectively.
[0006]
In addition, there was a single-function sounding body as a speaker or buzzer, which is a more ancient technology that can only generate sound output but not low-frequency sensation. In these sounding bodies, the magnetic circuit is fixed to the casing. However, in the above conventional example, the magnetic circuit can be made movable to serve as a vibrating mass, and can be multi-functionalized. However, this caused new problems. In other words, since a magnetic circuit with a large mass was supported by a relatively soft support spring, when an impact due to dropping or the like was applied to an electronic device equipped with a sounding body, the heavy magnetic circuit was greatly displaced, and the sounding body itself This is a cause of deformation or breakage of the casing, the support spring, the coil, the diaphragm, or other adjacent components.
[0007]
An object of the present invention is to increase the vibration mass in a multifunctional sound producing body, in particular, by giving an unusual shape to some parts of a magnetic circuit and by itself or in combination with other means. is there. Another object is to make effective use of the internal space of the sounding body when the mass of some parts of the magnetic circuit is increased. Yet another object is to simultaneously provide an effective shock resistance means for preventing damage to the sounding body due to the increased mass of the magnetic circuit.
[0008]
[Means for Solving the Problems]
In order to solve this problem, the structure of the multifunctional sounding body of the present invention has the following feature (1). In addition, (2) the following features may be provided at the same time.
[0009]
(1) A casing, a diaphragm that is supported by the casing and vibrates by receiving electromagnetic force of an acoustic frequency, and a vibration system that is elastically supported by the casing and constitutes a relatively low frequency vibration system. 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 vibration, the diaphragm is formed as a convex surface facing the outside of the casing, the surface of the permanent magnet on the diaphragm side is formed into a convex surface, and the shape of the convex surface is The surface should be almost parallel to the convex surface of the diaphragm .
[0010]
(2) A dish-shaped magnetic pole piece that forms a part of the magnetic circuit and follows the convex surface is fixed to the convex surface side of the permanent magnet .
[0011]
(3) Most of the mass elements constituting the relatively low-frequency vibration system are the sum of the masses of the parts constituting the magnetic circuit, and the spring elements are the sum of the spring properties of the support springs supporting the magnetic circuit. Be.
[0012]
(4) A motion limiting member is provided on the casing and the magnetic circuit to come into contact with each other when the relative displacement exceeds a predetermined value.
[0013]
(5) The motion limiting member provided on the housing side protrudes in the inner peripheral direction, the motion limiting member provided on the magnetic circuit side protrudes in the outer peripheral direction, and one of them extends in the thickness direction. It shall be configured so that the gap is maintained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of a multifunctional sound producing body according to the first embodiment of the present invention. Parts that are common in function to those already described in FIG. 3 are given the same symbols and names, and redundant description is omitted, and different parts are described. First, what is characteristic of the present invention is that the pole piece (top plate) 4c is not shaped like a disk as in the prior art, but is given a shape with a thick central portion like a plano-convex lens. The increase in mass is added to the vibration mass. The outer wall of the yoke 4a is further compensated for its mass by providing a sufficient radial thickness. In this way, the magnetic circuit 4 obtains a sufficient mass, and the additional mass (conventional example 4e) is omitted.
[0015]
The yoke 4a is not fixed to the casing 1, and is supported by a flat support spring 5 having a planar shape as shown in FIG. 5 so as not to touch the casing 1, and vibrates in the vertical direction (center axis direction). It is possible. The support spring 5 has an inner ring-shaped portion welded to the upper surface of a yoke 4a (not shown in FIG. 3), and has four flexible arms on the outer side. The upper case 1a is insert-molded and fixed. As a result, the magnetic circuit 4 has a structure in which the casing 1 is caught by a spring.
[0016]
Note that the natural frequency in the vertical direction of the magnetic circuit 4 is substantially determined by the mass of the magnetic circuit 4 mainly composed of the sum of the yoke 4a, the permanent magnet 4b, and the magnetic pole piece 4c, and the spring property of the arm portion of the support spring 5. . Therefore, when a low frequency current input close to the natural frequency is applied to the drive coil 3, the magnetic circuit 4 resonates and vibrates with a large amplitude, and outputs a low frequency vibration that can be experienced.
[0017]
Thickening the central portion of the pole piece 4c is a preferable shape that is magnetically meaningful. In any case, the pole piece 4c plays a role of bending the magnetic flux generated in the axial direction on the entire surface of the cylindrical permanent magnet 4b in a substantially right angle so as to reach the ring-shaped magnetic gap 4d from the inside. Since the magnetic flux density in the state should be large at the central portion of the pole piece 4c and small at the peripheral portion, a thick cross-section at the central portion can equalize the internal magnetic flux density, reduce the leakage magnetic flux and reduce the magnetic properties of the material used ( It is possible to provide a margin for the magnetic permeability.
[0018]
Increasing the thickness of the central portion of the pole piece 4c is meaningful in effectively utilizing the internal space of the multifunctional sounding body. In any case, since the diaphragm 2 needs to be rigid even if it is thin, it normally has a convex surface (substantially a part of a spherical surface) whose central portion faces outward. The substantially spherical surface of the pole piece 4c is substantially parallel to the curve of the diaphragm 2, and the increase in the thickness of the pole piece 4c fits well in the space behind the diaphragm 2, and the thickness of the multi-function sounding body Will not increase.
[0019]
The resin case 1 has an upper case 1a and a lower case 1b, which are fixedly attached to each other, and each includes movement limiting members 1c and 1d projecting inward of the cylindrical main body. A ring-shaped space having a “U” -shaped cross section is formed at an intermediate portion between both the movement limiting members. The yoke 4a is integrally formed from a soft magnetic metal material, and has a motion limiting member 4f projecting outward on the outer periphery.
[0020]
The movement limiting member 4 f on the outer periphery of the yoke 4 a is fitted into the ring-shaped space having a “U” -shaped cross section formed in the housing 1. However, an interval that does not contact the inner wall is set at an amplitude that gives a specified vibration output. However, when an impact or the like is applied and the magnetic circuit 4 is excessively displaced in any direction with respect to the housing 1, the motion limiting member 4f comes into contact with the motion limiting member 1c or 1d on the housing side and the maximum amount of displacement is increased. Limited. When the displacement of the outermost outermost part of the “U” -shaped cross-section space and the base cylindrical surface of the motion limiting member 4f is substantially cylindrical and the radial direction (lateral direction) of the sounding body, the motion limiting function May be fulfilled.
[0021]
FIG. 2 is a cross-sectional view of a multifunctional sound producing body according to the second embodiment of the present invention. The difference from the first embodiment of FIG. 1 is the shape of the permanent magnet 4b and the pole piece 4c, both of which are different in cross section from FIG. Other structures are the same as those in the first embodiment. In this example, the permanent magnet 4b has a convex lens shape to increase the vibration mass, and a dish-shaped magnetic pole piece 4c is in close contact with the convex surface. In the case of this example, the volume of the permanent magnet 4b itself increases, and therefore the amount of magnetic flux can also increase. The magnetic flux distribution inside the pole piece 4c is not as ideal as the first embodiment described above, but the effective magnetic flux gathered in the magnetic gap can be increased even if the leakage magnetic flux is somewhat increased. In a more extreme case, a structure in which the plate-shaped magnetic pole piece 4c is omitted can be considered. In any case, the space behind the diaphragm 2 can be used effectively, as in the first embodiment. As a modification of the present embodiment, a convex lens-shaped permanent magnet and a meniscus lens-shaped pole piece having a concave surface adapted to the surface thereof can be used.
[0022]
4A and 4B show a planar shape of the motion limiting member of the present invention, wherein FIG. 4A is a plan view showing a part of one embodiment, and FIG. 4B is a plan view of another embodiment. Each plan view shows only the housing 1 and the yoke 4a, and the other parts are not shown. In addition, since the motion limiting member of the present invention has an intricate structure, (1) when the magnetic circuit generates a vibration output, the air inside the “U” -shaped cross-section space is not in the motion limiting member 4f. There is a problem in that it must move around the outer narrow channel, fluid resistance is generated against vibration of the yoke, and vibration amplitude is insufficient. Further, (2) a problem in assembling the housing and the yoke occurs. Solutions to these problems in each embodiment will be described below.
[0023]
In the first embodiment shown in FIG. 4 (a), as a countermeasure of the above (1), a large number of small holes 4g are formed in the motion restricting member 4f, and an increase in air flow path is avoided to avoid an increase in fluid resistance. Yes. In the figure, a small hole is provided only on the yoke side, but if the movement limiting member on the housing side facing is provided with a hole to allow air to escape to the outside, the resistance will be further reduced. The position and shape of the small holes are also free, and a number of notches may be provided instead of the holes. Further, as a measure of the above (2) for providing the motion restricting member without any breaks on the entire circumference, as already described in the explanation of FIG. 1, the housing is composed of the case 1 and the case 2 and the yoke 4a is sandwiched between them. While trying to assemble.
[0024]
Further, in the second embodiment shown in FIG. 4B, each motion limiting member is not provided on the entire circumference but is divided by a large notch, and a space region in which air is confined as a plurality of sector shapes has a circumferential length. The above measures (1) were made by significantly reducing only the upper part and only the upper and lower sides. Of course, a small hole may be further provided on each sector. Further, since the motion limiting members 1c and 1d are provided so as not to overlap each other, the casing 1 is not separated, and integral injection molding is facilitated. When the yoke 4a is assembled, the motion limiting member 4f is rotated by about 22.5 ° (in the case of four sectors) from the position where it overlaps the motion limiting member 1d, so that the motion members 1c and 1d are overlapped in half. Thereafter, the yoke 4a and a support spring (not shown) are fixed by welding or the like, and the measure (2) is taken. Alternatively, the yoke and the support spring may be fixed first, the structure may be fitted from the back side of the housing, and then the periphery of the support spring and the housing may be fixed.
[0025]
Although each example of the embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above. Although the shape of the pole piece or permanent magnet in the present invention is relatively clearly defined, the material and details of the shape, the basic structure of the sounding body combined therewith, the presence or absence of a motion limiting member, the shape structure, and support Various other embodiments can be adopted by variously changing the spring shape or the like or mixing the characteristics of the components. For example, the motion limiting member may be provided at a different position or on another member, or at least one of the motion limiting members may be made of a soft material or coated. In the illustrated embodiment, the motion limiting member is two on the housing side and one on the yoke side. However, it is obvious that a substantially equivalent configuration and effect can be obtained even if the number relationship is reversed.
[0026]
【The invention's effect】
(1) In the present invention, the mass of the magnetic circuit can be increased by devising the shape of the pole piece or the permanent magnet into a convex shape.
[0027]
(2) By aligning the convex shape of the pole piece or the permanent magnet with the convex shape of the diaphragm, the internal space of the multifunctional sound producing body can be effectively used to prevent an increase in size.
[0028]
(3) By making the vibration mass substantially only the mass of the magnetic circuit, no additional mass is required, and the number of parts of the multifunctional sound producing body can be reduced.
[0029]
(4) Further, by providing a motion limiting member on the housing and the magnetic circuit, it was possible to prevent damage to the sounding body due to the application of impact to a large mass.
[0030]
(5) By engaging the member protruding in the inner peripheral direction from the housing and the member protruding in the outer peripheral direction from the magnetic circuit side, an effective motion limiting member structure can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multifunctional sounding body according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a multifunctional sounding body according to a second embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of a conventional multi-functional sounding body.
FIGS. 4A and 4B are plan views of a motion limiting member used in the present invention, and FIGS. 4A and 4B show different embodiments.
FIG. 5 is a plan view showing an example of a shape of a support spring used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 1a Upper case 1b Lower case 1c Motion limiting member 1d Motion limiting member 2 Diaphragm 3 Drive coil 4 Magnetic circuit 4a Yoke 4b Permanent magnet 4c Magnetic pole piece 4d Magnetic gap 4e Additional mass 4f Motion limiting member 4g Hole 5 Support spring 5a spoke

Claims (5)

A casing, a diaphragm that is supported by the casing 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 casing; 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 the multi-function type sounding body that vibrates , the diaphragm is formed as a convex surface facing the outside of the housing, the surface of the permanent magnet on the diaphragm side is formed into a convex surface, and the shape of the convex surface is formed on the diaphragm. A multifunctional sounding body characterized by a surface substantially parallel to the convex surface . 2. The multifunctional sound producing body according to claim 1, wherein a plate-like magnetic pole piece that forms a part of the magnetic circuit and follows the convex surface is fixed to the convex surface side of the permanent magnet . Most of the mass elements constituting the relatively low-frequency vibration system are the sum of the masses of the parts constituting the magnetic circuit, and the spring element is the sum of the spring properties of the support springs supporting the magnetic circuit. The multifunctional sounding body according to claim 1 or 2, wherein   The multifunctional type according to claim 1, 2 or 3, wherein the casing and the magnetic circuit are provided with a movement limiting member that comes into contact with the case when the relative displacement exceeds a predetermined value. Pronunciation body.   The motion limiting member provided on the housing side protrudes in the inner peripheral direction, the motion limiting member provided on the magnetic circuit side protrudes in the outer peripheral direction, and one of them maintains the gap in the thickness direction. The multifunctional sounding body according to claim 4, wherein the multifunctional sounding body is configured to be sandwiched.

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