JP4201322B2 - Sound structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a small sounding body having a function of a receiver or a speaker, which is used in an electronic information device such as a mobile phone.
[0002]
[Prior art]
FIG. 2 is a sectional view of a sounding body as an example of a conventional sounding body. The rough shape of the sounding body is a flat cylindrical shape, an elliptical shape or a rectangular shape as estimated from the cross-sectional view. In the figure, reference numeral 1 denotes a frame, which is made of a resin molded in a frame shape and supports and fixes each component of the sounding body. Reference numeral 2 denotes a yoke which forms a part of the magnetic circuit, and is made of a soft magnetic material, and its outer peripheral portion is insert-molded and integrated with the frame 1. A permanent magnet 3 is formed in a disk shape, is magnetized in the axial direction, and is fixed to the central portion of the yoke 2. A top plate 4 made of a soft magnetic material and forming a part of a magnetic circuit is fixed to the top.
[0003]
A cylindrical coil 5 for acoustic drive is inserted into a ring-shaped magnetic gap formed by the yoke 2 and the top plate 4. Reference numeral 6 denotes a vibration plate made of a resin film. The coil 5 is fixed to the lower surface, and the vibration plate 6 vibrates due to an audio current flowing through the coil 5. The diaphragm 6 is dimensioned as much as possible in the frame 1. The protector 7 is a dish-like metal plate for protecting the thin and fragile diaphragm 6 and has a sound emitting hole 7a. The protector 7 has substantially the same outer shape as the diaphragm 6, and the peripheral edges of the diaphragm 6 and the protector 7 are both The frame 1 is fixed to a stepped portion in the recess 1 a provided on the inner peripheral edge of the frame 1.
[0004]
The inner side of the peripheral edge of the diaphragm 6 is given a bent shape with a large number of wrinkles in the cross section in order to facilitate vibration, and the portion 6a inside the coil 5 is called a main dome and imparts appropriate rigidity. Therefore, a relatively simple bent shape such as a convex surface or a concave surface is given. In this conventional example, the main dome 6a has a surface shape that is convex outward at the end edge but concave at the center (convex toward the magnetic circuit). Further, the inner surface of the protector 7 is usually mostly flat.
[0005]
[Problems to be solved by the invention]
For example, when a mobile phone is dropped, the diaphragm is greatly bent by a strong impact, or the air pressure in the part called the rear air chamber inside the diaphragm (on the magnetic circuit side) suddenly increases. Permanent deformation may remain. The rear air chamber is a space on the magnetic circuit side behind the diaphragm. In order to improve the acoustic characteristics of the vibration of the speaker, the rear air chamber is not sealed, but communicates with the space outside the sounding body through a dedicated hole or notch provided in the frame, so pressure changes from outside May be introduced into the rear chamber.
[0006]
Due to such an abnormal force, for example, a permanent deformed portion 6b as indicated by a dotted line in FIG. 2 may remain in the main dome 6a. (In this case, the central portion of the main dome 6a is inverted and the unevenness is reversed.) When the diaphragm is deformed in this way, its original acoustic characteristics are lost, and the volume, sound quality, frequency characteristics, etc. of the speakers are lost. Often worse than the original characteristics.
An object of the present invention is to provide a structure of a sounding body that prevents permanent deformation from remaining in the main dome of the diaphragm due to an abnormal cause.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the sounding body of the present invention has the following characteristics.
(1) Made of a resin film in which a magnetic circuit integrated with a frame and a cylindrical coil that is supported by the frame at the periphery and inserted into a ring-shaped magnetic gap formed by the magnetic circuit are fixed. In a sounding body having a diaphragm and a sound emitting body having a sound emitting hole and a peripheral portion held by the frame and protecting the outside of the diaphragm, a cross-sectional shape of at least a central portion of the main dome of the diaphragm, And a cross-sectional shape of at least the central portion of the portion facing the main dome of the protector is projected with a smooth curved surface so as to be substantially parallel to each other toward the inside of the sounding body, and the central portion of the protector providing the part sound emission hole.
[0008]
The sounding body of the present invention may further have the following features.
The cross-sectional shape of at least the central part of the main dome of the diaphragm, the cross-sectional shape of at least the central part of the part facing the main dome of the protector, and the shape of the surface of the top plate on the diaphragm side are smooth concave surfaces. thing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a sectional view of a sounding body as an example of an embodiment of the present invention. Since it is the same as that of the conventional example shown in FIG. 2 except for the part related to the present invention, the description of the common parts in each figure will be omitted. The difference from the conventional example in this example is that a convex portion 7 b having a convex surface facing inward (magnetic circuit side) is provided at the center of the protector 7.
[0010]
With such a configuration, for example, when the pressure in the rear chamber of the diaphragm 6 suddenly increases, the main dome 6a of the diaphragm tries to invert and protrude outward as shown in 6b in FIG. Due to the air pressure, it is greatly displaced outward and is strongly pressed against the inner surface (lower surface in the figure) of the convex portion 7b of the protector 7, so that reverse deformation is prevented. Further, even when the diaphragm 6 is displaced outward due to the inertia caused by the impact force and is pressed against the protector 7, the convex portion 7b does not allow the main dome 6a to be deformed.
[0011]
Regarding the embodiments of the present invention, various modifications and examples of other forms are conceivable in addition to the above-described forms, and these will be referred to (illustration is omitted).
First, depending on how an abnormal situation occurs (pressure direction, impact direction, etc.), the diaphragm 6 may be displaced inward, and the main dome 6 a may contact the surface of the top plate 4. Therefore, it is preferable to give the surface of the top plate 4 a shape that can prevent the deformation of the main dome 6 a as well as the inner surface of the protector 7. Also in this example, the effect of preventing deformation is to catch at least the central part of the excessively displaced diaphragm with a wide area as much as possible so that the unevenness is not reversed (in a shape substantially along the original unevenness).
[0012]
Although the modified example is not shown again, if the original shape of the central portion of the main dome 6a is convex inward as shown in FIG. 1 or 2, the surface of the protector 7 may be concave. In this case, the top plate 4 form of itself, the side of the permanent magnet 3 is made into a shape similar to the flat plano-concave lens.
[0013]
【The invention's effect】
In the present invention, by providing the inner surface of the protector with a shape corresponding to the shape of the main dome of the diaphragm, permanent deformation of the diaphragm when an abnormal force is applied can be prevented. Furthermore, by changing the shape of the top plate, it was possible to prevent permanent deformation of the diaphragm even when an abnormal force in a different direction was applied.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a sounding body as an example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a sounding body as an example of a conventional sounding body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Frame 1a Concavity 2 Yoke 3 Permanent magnet 4 Top plate 5 Coil 6 Diaphragm 6a Main dome 6b Deformation part 7 Protector 7a Sound emission hole 7b Convex part

Claims (2)

A magnetic circuit integrated with the frame, and a diaphragm made of a resin film, to which a peripheral portion is supported by the frame and a cylindrical coil inserted into a ring-shaped magnetic gap formed by the magnetic circuit is fixed. A sounding body having a sound emitting hole, a peripheral portion of which is held by the frame, and having a protector that protects the outside of the diaphragm, a cross-sectional shape of at least a central portion of the main dome of the diaphragm, and the protector The cross-sectional shape of at least the central portion of the portion facing the main dome of each of the two is protruded with a smooth curved surface so as to be substantially parallel to each other toward the inside of the sounding body, and a part of the central portion of the protector A structure of a sounding body characterized by providing a sound emitting hole . The cross-sectional shape of at least the central part of the main dome of the diaphragm, the cross-sectional shape of at least the central part of the part facing the main dome of the protector, and the shape of the surface of the top plate on the diaphragm side are smooth concave surfaces. The structure of a sounding body according to claim 1.

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