JPH05137194A - Domic speaker - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the peak of the sound pressure frequency characteristics of the first high-frequency resonance in a dome-type speaker. [Structure] A dome type diaphragm 7 is attached to a voice coil 9 inserted in an air gap 5 of a field part, and an edge 6 held on a frame 1 supports a vibration system. The braking piece 11 is provided near the back surface of the dome-shaped diaphragm 7 connected to the voice coil 9.
Is attached in a substantially annular shape. The braking piece 11 damps the entire outer periphery of the dome-shaped diaphragm 7 and suppresses the first-order high-frequency resonance mode of the sound pressure frequency characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of frequency characteristics of a speaker, and more particularly to a dome type speaker with reduced first high frequency resonance.

[0002]

2. Description of the Related Art A dome-type speaker has a sound pressure-frequency characteristic extending to a high frequency range as compared with a cone-type speaker, but does not have a damper used in a cone-type diaphragm in a voice coil section, so It has a high sound pressure peak called the resonance. Therefore, it is desired to reduce the peak of sound pressure at a specific frequency and obtain a flat sound pressure frequency characteristic.

The structure of a conventional dome type speaker will be described with reference to FIG. FIG. 6 is a cross-sectional view taken along the central axis showing an example of a conventional dome type speaker.
In the figure, the frame 1 is a mounting portion having an opening fixed to the housing of the speaker body. A top plate 2 made of an annular magnetic material is attached to the back surface of the frame 1. A cylindrical magnet 3 is coaxially fixed to the rear surface of the top plate 2, and the magnet 3
The yoke 4 is attached to the other surface. The yoke 4 is a member having an inverted T-shape in cross section including the central axis thereof, and is a magnetic body in which a cylindrical center pole and a disk-shaped plate holding the center pole are integrally formed at the center thereof. The upper side surface of the center pole of the yoke 4 forms a uniform space with the cylindrical inner peripheral surface of the top plate 2, and this space is called an air gap 5.

As described above, the magnetic circuit including the top plate 2, the magnet 3, the yoke 4 and the air gap 5 is
It constitutes the field portion of the voice coil described later. In the air gap 5, the magnetic flux generated from the magnet 3 penetrates the center pole of the yoke 4 via the top plate 2 to form a uniform magnetic field. Next, an annular edge 6 is bonded to the inner peripheral portion of the frame 1. Edge 6
A bent portion having an arc-shaped cross section is formed on the inner periphery of the, and the bent portion holds the outer peripheral portion of the dome-shaped diaphragm 7 in a freely vibrating manner.

The dome type diaphragm 7 is a hemispherical diaphragm and is made of, for example, paper, light metal, plastic or the like. Further, the dome-shaped diaphragm 7 includes a hemispherical portion and an elastic portion 7a in the periphery thereof, and is held by the edge 6 via the elastic portion 7a. Further, the dome type diaphragm 7 is connected to the upper end of the cylindrical portion 8. The cylindrical portion 8 is a coil bobbin inserted into the air gap 5, and the voice coil 9 is wound around the outer peripheral side surface thereof. When an exciting current is applied to the voice coil 9, an electromagnetic force is applied by the magnetic field of the air gap 5, and the dome-shaped diaphragm 7 makes a piston movement integrally with the cylindrical portion 8.

FIG. 7A is an equivalent circuit showing the vibration characteristics of the conventional dome type speaker. The driving force F is an electromagnetic force that the voice coil 9 receives from the magnetic field of the air gap 5, and equivalently serves as a power source. The current I flowing in this circuit indicates the vibration speed of the dome-shaped diaphragm 7, and the current value is determined by the load connected to the driving force F. Of this load, the compliance C1 is equivalent to the elastic coefficient of the elastic portion 7a on the outer periphery of the dome diaphragm 7, and the inductance M1 is equivalent to the mass of the dome diaphragm 7. The resonance circuit formed by the compliance C1 and the inductance M1 determines the first high-frequency resonance frequency. The second,
The third-order and higher-order resonance circuits are formed by the compliances C2, C3 ... And the inductances M2, M3.

The frequency characteristic of the sound pressure in the dome type speaker having such a structure is as shown in FIG. 8, for example.
That is, the voice frequency band from 20H _z to 20 kHz _z, but characteristic with a gentle peak around a band of midrange is obtained, the peak of the large sound pressure is generated in the narrowband portion of 4～5KH _z .. This resonance frequency is due to the resonance of the mass of the dome-shaped diaphragm 7 and its elastic portion 7a, and the frequency thereof is the elasticity of the edge 6 and the speed of sound of the material forming the dome-shaped diaphragm 7, the height of the diaphragm, and the diameter. Is known to depend on.

Therefore, in order to reduce this resonance, for example, as shown in FIG. 6, there has been proposed a dome type speaker in which an annular braking piece 10 is attached to the center of the inner surface of a dome type diaphragm 7. The braking piece 10 is, for example, a dome-shaped speaker having a diameter of 12 cm, and is an annular butyl rubber braking piece having a diameter of 20 mm and a thickness of 1 mm. FIG. 9 shows the measured sound pressure frequency characteristics of the speaker when this braking is attached. In this case, the damping effect of the braking piece 10 suppresses the resonance of the central portion of the dome-shaped diaphragm 7, and the peak of the first high-frequency resonance of the sound pressure frequency characteristic is slightly reduced.

FIG. 7B is an equivalent circuit showing the vibration characteristics of the dome-type speaker to which the braking piece 10 is attached. What is different from FIG. 7A is that an inductance Md equivalent to the mass of the braking piece 10 is connected in series with the inductance M1 indicating the mass of the dome-shaped diaphragm 7. Originally, the braking piece 10 has both a mass and a viscous resistance, but exhibits a damping effect only when an external force that deforms the braking piece itself is applied. However, in this embodiment, since it is attached to the top of the dome-shaped diaphragm 7, it is presumed that the braking piece 10 vibrates integrally with this and the damping effect is small, and only the mass effect is exerted.

[0010]

As described above, in the above-mentioned conventional dome type speaker, the outermost deformed outer peripheral portion of the dome type diaphragm 7 is not damped in the first high frequency resonance mode. There is a problem that the secondary high frequency resonance mode cannot be suppressed sufficiently and the resonance peak of the sound pressure frequency characteristic cannot be eliminated.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a dome-type speaker in which the first high-frequency resonance of the sound pressure frequency characteristic is suppressed.

[0012]

According to a first aspect of the present invention, a frame for fixing a speaker body and having an opening,
It includes an annular top plate, a cylindrical magnet fixed to the rear surface of the top plate, a yoke that holds the magnet and has a cylindrical surface facing the inner peripheral side surface of the top plate through an air gap, and is fixed to the back surface of the frame. Field that generates magnetic flux in the air gap, a voice coil that is inserted into the air gap of the field, a dome-type diaphragm that vibrates when attached to the voice coil, and a dome-type that is attached to the opening of the frame A dome-shaped speaker having an edge that vibratably holds the outer periphery of the diaphragm, comprising a braking piece that is concentrically mounted in the vicinity of the voice coil connection portion of the dome-shaped diaphragm.

According to a second aspect of the present invention, a speaker main body is fixed, a frame having an opening, an annular top plate, a cylindrical magnet fixed to the rear surface of the top plate, and a top plate which holds the magnet. A field magnet portion, which includes a yoke having cylindrical surfaces facing each other with an air gap on the peripheral side surface, is fixed to the back surface of the frame and generates a magnetic flux in the air gap, and a voice coil inserted into the air gap of the field magnet portion. A dome-shaped speaker having a dome-shaped diaphragm attached to a voice coil and vibrating, and an edge attached to an opening of a frame and vibratingly holding an outer periphery of the dome-shaped diaphragm, the inner periphery of the voice coil being a voice coil. It is characterized by comprising a braking piece mounted concentrically from the upper end portion to the vicinity of the connection portion on the back surface of the dome-shaped diaphragm.

[0014]

According to the present invention having such characteristics, the dome type diaphragm is attached to the voice coil inserted into the air gap of the field part, and the braking piece is attached near the connection part of the voice coil. This braking piece acts viscously on the diaphragm. For this reason, the outer peripheral portion of the dome-shaped diaphragm, which is most deformed, is damped, so that a speaker having a sound pressure frequency characteristic in which the primary high-frequency resonance mode is suppressed is obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dome type speaker according to a first embodiment of the present invention will be described below with reference to the sectional view of FIG. Since the configuration other than the braking piece is the same as the conventional example shown in FIG. 6,
The same parts are designated by the same reference numerals and detailed description thereof is omitted.

The dome-shaped diaphragm 7 is fixed to the cylindrical portion 8, and the frame 1 of the speaker is provided via the elastic edge 6.
Supported by. The field part is the top plate 2, the magnet 3, the center pole of the yoke 4, the air gap 5
The field magnet portion applies a uniform magnetic field to the voice coil 9 as in the conventional example.

In the present embodiment, the braking piece 11 is attached to the rear surface of the dome type diaphragm 7 in the vicinity of the cylindrical portion 8 connected to the voice coil 9. The braking piece 11 is an annular braking member having elasticity.

In the dome type speaker having such a structure,
When a voice current is applied to the voice coil 9, an electromagnetic force is received by the magnetic flux of the air gap 5, and the cylindrical portion 8 holding the voice coil 9 makes a piston motion according to the voice current. This vibration is transmitted to the dome-shaped diaphragm 7, and sound is generated by the vibration of the air in contact with the diaphragm. As the frequency becomes higher, the entire inner peripheral part of the dome-shaped diaphragm 7 becomes a mass as a driving load, and the outer peripheral part of the diaphragm including the edge 6 elastically operates, and the dome-shaped diaphragm 7 shown in FIG. As shown by the broken line, the portion of the dome-shaped diaphragm 7 near the edge 6 is deformed and vibrates.
This deformation vibration causes a first-order high frequency resonance mode in the sound pressure frequency characteristic. However, here, since the braking piece 11 is attached to the rear surface of the dome-shaped diaphragm 7 in the vicinity of the connection portion with the cylindrical portion 8, the viscous element is connected to the elastically operating portion, which is the most The entire outer circumference of the dome-shaped diaphragm 7 that vibrates with large deformation is damped.

FIG. 2B is an equivalent circuit showing the vibration characteristics of the dome type speaker of this embodiment. Unlike FIG. 7 of the conventional example, the viscous resistance R1 of the vibrating piece 11 is added in series with the equivalent compliance C1 of the elastic portion 7a of the dome type diaphragm 7. Therefore, the equivalent mass M of the dome-shaped diaphragm 7
1 and a damping element are added to the resonance circuit formed by the equivalent compliance C1 of the elastic portion 7a, and the first-order high-frequency resonance mode that has been determined by this resonance circuit is suppressed. Therefore, it is possible to sufficiently reduce the sound pressure peak due to the resonance of the conventional sound pressure frequency characteristic.

FIG. 3 shows the sound pressure frequency characteristics of the dome type speaker in this embodiment. Here, for example, in a dome type speaker having a diameter of 12 cm, butyl rubber having a width of 6 mm and a thickness of 0.5 mm is attached to the inside of the dome type diaphragm 7 via an adhesive material. The dome-type speaker of this embodiment has approximately 4.5 k
It can be seen that the sound pressure peak at the frequency of Hz is sufficiently reduced and a flatter sound pressure frequency characteristic is obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment has the same structure as the first embodiment except that the mounting position of the braking piece is different, so only the braking piece will be described. On the back surface of the dome-shaped diaphragm 7, a braking piece 12 is attached in a belt shape over the vicinity of the connection portion with the voice coil 9 and the inner surface of the end of the cylindrical portion 8. The braking piece 12 is a ring-shaped braking member made of the same material as that of the first embodiment.

The sound pressure generating operation of the dome-type speaker having such a structure is similar to that of the first embodiment, but the upper end portion of the inner circumference of the voice coil 9 is also damped by the braking piece 12, so that the primary height is increased. When the outer circumference of the dome-shaped diaphragm 7 is deformed in the area resonance, the upper end of the cylindrical portion 8 is suppressed from being deformed together. Therefore, the peak of the first-order high-frequency resonance mode can be sufficiently reduced.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the dome type speaker according to the third example when cut at the upper part of the frame. This embodiment also has the same configuration as the first embodiment except that the shape and mounting position of the braking piece are different, so only the braking piece will be described. Four braking pieces 13, for example, are attached on the back surface of the dome-shaped diaphragm 7 in the vicinity of the connection with the voice coil 9. The braking piece 13 is, for example, a belt-shaped braking member made of the same material as that of the first embodiment.

In the dome type speaker constructed as described above, the piston vibration generated in the voice coil 9 is transmitted to the dome type diaphragm 7 to generate sound, but the braking piece 13 is divided into small pieces and attached. Therefore, the mass and the viscosity locally increase in the portion where these braking pieces are attached.
Therefore, the vibration mode of the outer peripheral portion of the dome-shaped diaphragm, which operates elastically in the first resonance mode and has the largest deformation, is made non-uniform. Therefore, the sound pressure frequency characteristic in which the first high-frequency resonance mode is suppressed can be obtained. Also, the braking piece 13
Since it is divided into small pieces, it has an advantage that it can be easily attached to the diaphragm and the speaker is excellent in mass productivity.

In this embodiment, of the braking pieces 13,
Some of them may be attached to the back surface of the dome-shaped diaphragm 7 in the vicinity of the voice coil joint portion, and others may be attached to the rear surface of the dome-shaped diaphragm 7 from the inner peripheral upper end of the cylindrical portion 8. can get. Further, although the number of the braking pieces 13 is four in this embodiment, the same effect can be obtained with a number other than this. or,
Even in the case of a dome-type speaker in which the dome-type diaphragm 7 and the voice coil cylindrical portion 8 are integrally formed, it is apparent that the same effect can be obtained by attaching them as in the first to third embodiments. ..

[0026]

As described above, according to the present invention, the viscous action of the vibrating plate can be obtained by dividing and attaching the braking piece in the vicinity of the voice coil connection portion of the dome type diaphragm in an annular shape or in small pieces. Working, the first high-frequency resonance mode of the sound pressure frequency characteristic is suppressed. Therefore, it is possible to obtain the effect that a dome-type speaker having excellent frequency characteristics can be realized without changing the configurations of the field unit of the speaker and the diaphragm itself.

[Brief description of drawings]

FIG. 1 is an axial sectional view of a dome type speaker according to a first embodiment of the present invention.

FIG. 2A is an explanatory diagram showing a vibration state of a diaphragm of a dome-type speaker, and FIG. 2B is an equivalent circuit showing a vibration characteristic of the dome-type speaker of the first embodiment.

FIG. 3 is a sound pressure frequency characteristic diagram of the dome type speaker of the first embodiment.

FIG. 4 is an axial sectional view of a dome type speaker according to a second embodiment of the present invention.

FIG. 5 is a cutaway view of an upper surface of a frame of a dome type speaker according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional dome type speaker.

FIG. 7 is an equivalent circuit showing vibration characteristics of a conventional dome-type speaker.

FIG. 8 is a sound pressure frequency characteristic diagram of a conventional dome-type speaker (No. 1).

FIG. 9 is a sound pressure frequency characteristic diagram (part 2) of the conventional dome speaker.

[Explanation of symbols]

 1 frame 2 top plate 3 magnet 4 yoke 5 air gap 6 edge 7 dome type diaphragm 8 cylindrical portion 9 voice coil 11, 12, 13 braking piece

Claims (3)

[Claims] 1. A frame for fixing a speaker body and having an opening, an annular top plate, a cylindrical magnet fixed to the rear surface of the top plate, and an air on the inner peripheral side surface of the top plate for holding the magnet. A field coil section including yokes having cylindrical surfaces facing each other through a gap, the field section being fixed to the back surface of the frame to generate a magnetic flux in the air gap; and a voice coil inserted into the air gap of the field section, A dome-shaped speaker having a dome-shaped diaphragm attached to the voice coil and vibrating, and an edge attached to an opening of the frame and vibratingly holding an outer periphery of the dome-shaped diaphragm, the dome-shaped speaker A dome shape including a braking piece attached concentrically in the vicinity of the connection portion of the voice coil of the mold diaphragm. Speaker. 2. A frame for fixing a speaker body and having an opening, an annular top plate, a cylindrical magnet fixed to the rear surface of the top plate, and an air on the inner peripheral side surface of the top plate for holding the magnet. A field coil section including yokes having cylindrical surfaces facing each other through a gap, the field coil section being fixed to the back surface of the frame to generate a magnetic flux in the air gap; and a voice coil inserted into the air gap of the field section, A dome type speaker having a dome type diaphragm attached to the voice coil and vibrating, and an edge attached to an opening of the frame for vibratingly holding an outer periphery of the dome type diaphragm, the voice comprising: A braking piece is concentrically attached from the upper end of the inner circumference of the coil to the vicinity of the connecting portion on the back surface of the dome-shaped diaphragm. Dome type speaker characterized and. 3. The dome type speaker according to claim 1, wherein the braking piece is divided into a plurality of small pieces.