JPH09247791A - Reverse dome type speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the strength of a speaker diaphragm and to secure an accurate position of a voice coil bobbin by providing plural concentric ring- shaped ribs on the back of the diaphragm being undergone the injection molding. SOLUTION: A group 15 of concentric ring-shaped ribs 15a to 15d is provided on the back of a speaker diaphragm 1, and a voice coil bobbin 2 is positioned at the inner circumference of the rib 15b and fixed to the diaphragm 1. In this bonding process, the concave side of the diaphragm 1 is turned up and an adhesive is applied to the inner circumference of the rib 15b. Then the bobbin 2 is put on the rib and fixed there. At the same time, the outflow of the adhesive is prevented by the rib and a sink part is formed to secure the accurate adhesion. The flake type natural or artificial mica having an aspect ratio of 15 or more is added to the olefin resin by the injection molding for production of the diaphragm 1 that has an optional section including a recess part, and the bobbin 2 is fit into this recess part. Thus it is possible to position the bobbin with higher accuracy, to bond the bobbin with high stability and also to prevent or correct the deformation of the bobbin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker which is a type of audio equipment, and more particularly to a reverse dome type speaker in which a diaphragm has a front vertical section and a curved surface thereof projects downward in a dome shape.

[0002]

2. Description of the Related Art The structure of a conventional inverted dome type speaker will be described with reference to FIG. In the figure, reference numeral 1 is a diaphragm made of wood pulp, aluminum or the like having a curved surface protruding downward in a dome shape. Reference numeral 2 is a voice coil bobbin wound with a voice coil 2a, 3 is a damper holding the voice coil bobbin 2, 4 is an edge holding the outer periphery of the diaphragm 1,
Reference numeral 5 denotes a yoke having an inverted T-shaped cross section including a center pole portion 5a and a flange portion 5b, 6 a ring-shaped magnet, 7 a ring-shaped plate, 8 an inner peripheral surface of the plate 7 and an upper outer periphery of the center pole portion 5a. A magnetic gap formed between the surfaces, 9 is a through hole provided in the yoke 5, 10 is a frame, and 11 is a gasket.

The inverted dome type speaker has a shallow dome shape, so that it can obtain an appropriate shape rigidity and, in addition, an ideal performance without the effect of the anterior chamber. On the other hand, in the cone type speaker, the sound pressure characteristic is generally disturbed due to the front chamber effect due to the depression in the front surface of the diaphragm. In addition, it is difficult to obtain the rigidity of the diaphragm in the flat speaker, and the high frequency characteristics do not extend.

Since the inverse dome type speaker does not have the cap portion adhered and the diaphragm is integrated, there is little variation in the high frequency characteristics and it is stable. Further, since the shape is spherical and the rigidity is high, the divided vibration frequency becomes high, and the distortion in the middle frequency range can be reduced.

The inverted dome type speaker has a concave diaphragm and does not require a short horn, so that flat characteristics can be obtained and a clear sound quality can be reproduced without a protector such as an equalizer or a metal cover.

The inverted dome type speaker has a diaphragm outer shape of about 0.
By driving the optimum position inside 75 times and controlling the high frequency characteristics, it is possible to further improve the directivity as compared with the dome type speaker having the same diameter.

In the inverted dome type speaker, since the diaphragm can be made shallow, the difference in signal arrival time from each speaker unit to the listening position is small in the multi-way type speaker, and there is little difference in crossover due to phase shift. Waveform distortion is reduced. In addition, this phase difference can be completely corrected with a slight adjustment of the position before and after the unit, and the structure of the baffle plate becomes simple.

[0008]

However, in the conventional inverted dome type speaker, when the voice coil bobbin is joined to the diaphragm, it is extremely difficult to perform accurate positioning and to apply the adhesive stably, which is a workability problem. There was a problem that was bad. In addition, the conventional diaphragm made of a material such as wood pulp or aluminum has a problem that peaks and f-characteristics are generated in the high range.

The present invention has been proposed in view of the above, and its main object is to accurately position the bonding of the voice coil bobbin to the diaphragm and to easily apply the adhesive. Therefore, it is possible to provide an inverted dome type speaker having improved workability and improved quality by using a diaphragm whose main material is a specific thermoplastic resin.

[0010]

Means for Solving the Problems A plurality of concentric ring-shaped ribs are provided on the back surface of a diaphragm of an inverted dome type speaker. These ribs increase the strength of the diaphragm and are used as guides for positioning the voice coil bobbin. Further, by joining the voice coil bobbin to the diaphragm at the position of the rib, it can be expected that the deformation of the voice coil bobbin is prevented and corrected. Further, the upper diameter of the voice coil bobbin can be processed, molded, or made larger by tapering with an adapter, etc., and the driving position of the diaphragm can be adjusted to select the characteristics.

Further, the voice coil bobbin is joined to the diaphragm with one rib, and a ring-shaped throat is arranged between the upper portion of the voice coil bobbin and the other ribs. Due to this throat, the adhesive strength between the voice coil bobbin and the diaphragm is increased, the reliability at the time of high input is increased, the sound pressure characteristic stability and variation are reduced, and the desired characteristic can be obtained by changing the driving point.

Further, an olefin resin is used as a main material of the diaphragm formed by injection molding. Further, excellent high-frequency characteristics can be obtained by blending a reinforcing material with the olefin resin as the main material. For example, a reinforcing material made of flake-shaped natural mica or artificial mica having an aspect ratio of 15 or more is used in an amount of 20 to 5
Excellent high-frequency characteristics can be obtained by using the one blended with the olefin resin as the main material at a 0% weight ratio.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION To achieve the above object, an inverted dome type loudspeaker according to the present invention is a reverse dome type loudspeaker in which a diaphragm shape is a front vertical section and a curved surface thereof projects downward in a dome shape. Is formed by injection molding using a thermoplastic resin as a main material, and a plurality of concentric ring-shaped ribs 15a, 15b, 15c, 1 are formed on the back surface of the diaphragm 1.
It is characterized in that a rib group 15 composed of 5d to 5d is provided and the voice coil bobbin 2 is fixed to the diaphragm 1 using one of the rib groups 15 as a guide.

The inverted dome type speaker according to the present invention is characterized in that a ring-shaped throat 22 is provided between the voice coil bobbin 2 and another rib of the rib group 15. .

Further, the inverted dome type speaker according to the present invention is characterized in that the diaphragm 1 is made of an olefin resin or a mixture of an olefin resin and a reinforcing material.

Alternatively, the reinforcing material to be blended with the olefin resin is characterized in that the flaky natural mica or artificial mica having an aspect ratio of 15 or more is contained in a weight ratio of 20 to 50%.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view of an inverted dome type speaker according to the first embodiment. The same reference numerals as those in FIG. 6 indicate the same elements, and a description thereof will be omitted.
In the figure, 15 is a plurality of concentric ribs 15a, 15b, 15c, 1 provided on the back surface of the inverted dome-shaped diaphragm 1.
It is a rib group consisting of 5d. In the embodiment, the voice coil bobbin 2 is positioned on the inner circumference of the rib 15b and fixed to the diaphragm 1. That is, in the joining step, an adhesive is applied to the inner circumference of the rib with the convex surface of the vibration plate 1 facing upward, and the voice coil bobbin 2 is placed and bonded from above, and the rib prevents the adhesive from flowing out. Since the adhesive reservoir is formed, the bonding can be performed more easily and accurately.

The vibrating plate 1 is formed by injection molding a mixture of an olefin resin and a reinforcing material composed of flake-shaped natural mica having an aspect ratio of 15 or more or artificial mica in a weight ratio of 20 to 50%. The cross-sectional shape of the ribs of the diaphragm 1 can be designed to be a shape suitable for the application such as a square, a semicircle, and a triangle. In addition, the voice coil bobbin 2 has
It can be expected that more accurate positioning, stable joining, prevention of deformation of the voice coil bobbin 2 and correction thereof can be achieved by fitting.

FIG. 2 is a half sectional view of another inverted dome type speaker according to the first embodiment. The same reference numerals as those in FIG. 1 denote the same elements, and a description thereof will be omitted. In the figure, reference numeral 21 denotes a voice coil bobbin whose upper diameter is machined, molded, or made to have a tapered diameter by an adapter or the like. This voice coil bobbin 21 has a rib 1
It is positioned on the inner circumference of 5c and fixed to the diaphragm 1. Rib 1 with the upper diameter of the voice coil bobbin 21
The characteristic can be selected by adjusting the driving position of the diaphragm 1 by the diameter of 5c.

FIG. 3 is a half cross-sectional view of the inverted dome type speaker according to the second embodiment. FIG. 1 shows a ring-shaped throat 22.
Is added. In the embodiment, this throat 22
Is arranged between the upper portion of the voice coil bobbin 2 and the rib 15d, and the voice coil bobbin 2 is positioned on the inner circumference of the rib 15b and fixed to the diaphragm 1.

However, in the case of this structure, in order to adjust the desired characteristics, the diaphragm 1 and the voice coil bobbin 2 are connected only by the adhesive between the diaphragm 1 and the throat 22, and the voice coil bobbin 2 and the diaphragm 1 are connected. It may not be fixed directly.
The throat 22 increases the adhesive strength between the voice coil bobbin 2 and the diaphragm 1, and the driving position of the diaphragm 1 can be adjusted by the size of the upper aperture of the throat 22 and the diameter of the rib 15d to select the characteristics. Workability is improved

FIG. 4 is a diagram showing the physical properties of the material used for the diaphragm. In each of Examples A and B, polypropylene resin was used as the olefin resin, and the diaphragm in Example A was injection molded 100% polypropylene resin, and corresponds to claim 3.
The diaphragm in Example B is a mixture of polypropylene resin and 40% by weight of a reinforcing material composed of flake-shaped mica with an aspect ratio of 30 and is injection-molded, which corresponds to claim 4. The diaphragm in the conventional example C uses wood pulp. From the Young's modulus, density, internal loss, and propagation speed of these three types of materials, it is understood that the material of Example B is the most excellent.

FIG. 5 shows a comparison of sound pressure-frequency characteristics between the present invention and the conventional example. This comparative test was performed by incorporating the diaphragm using the material in FIG. 4 into a 12 cm midrange speaker. The solid line A is the embodiment A in FIG.
And the solid line B is the embodiment B in FIG. 4, and the broken line C is
Is a conventional example C in FIG. As is clear from the figure, the solid line A has a Young's modulus smaller than that of wood pulp, so that the solid line A does not grow in the high range, but the peak and the f-characteristics are eliminated. The solid line B also has a characteristic that the high range also extends and becomes flat, and the dip in the high range is flattened and a remarkable improvement is seen in the reproduction characteristic in the high range. In the examples, polypropylene was used as the olefin resin,
The same effect can be obtained by using other olefin resin such as polyethylene.

[0024]

As described above, according to the present invention as set forth in claim 1, the diaphragm of the inverted dome type speaker is formed by injection molding using a thermoplastic resin as a main material, and a plurality of concentric rings are formed on the back surface. By providing the ribs, the strength of the diaphragm is increased, and since it is used as a guide for positioning the voice coil bobbin, the positioning can be accurately performed, and the adhesive can be easily applied. The quality and workability can be improved.

According to the second aspect of the present invention, by providing a plurality of concentric ring-shaped ribs on the back surface of the diaphragm of the inverted dome type speaker, the strength of the diaphragm is increased and the voice coil bobbin is formed. It is used as a guide for positioning, and a ring-shaped throat is arranged between the upper part of the voice coil bobbin and other ribs, so that more accurate positioning can be performed and adhesive is easily applied. Therefore, the quality and workability can be improved.

Further, according to the present invention as set forth in claims 3 and 4, an olefin resin is used as a main material of the vibration plate formed by injection molding, and a reinforcing material is mixed with the olefin resin of the main material. In addition, the use of a flake-shaped natural mica or artificial mica having an aspect ratio of 15 or more in the olefin resin as the main material can be increased by 20 to
Excellent high-frequency characteristics can be obtained by using a mixture of the reinforcing materials in a weight ratio of 50%.

[Brief description of drawings]

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

FIG. 2 is a half cross-sectional view of another inverted dome type speaker according to the first embodiment of the present invention.

FIG. 3 is a half sectional view of an inverted dome type speaker according to a second embodiment of the present invention.

FIG. 4 is a diagram showing physical properties of materials used for the diaphragm.

FIG. 5 shows frequency characteristics of the present invention and a conventional example with respect to sound pressure.

FIG. 6 is a half sectional view of an inverted dome type speaker in a conventional example.

[Explanation of symbols]

 1 diaphragm 2 voice coil bobbin 2a voice coil 3 damper 4 edge 5 yoke 5a center pole part 5b flange part 6 magnet 7 plate 8 magnetic gap 9 through hole 10 frame 11 gasket 15 rib group 15a, b, c, d rib 21 voice coil bobbin 22 throat

Claims (4)

[Claims] 1. A reverse dome type loudspeaker in which the shape of a diaphragm is a front vertical section and the curved surface thereof projects downward in a dome shape, wherein the diaphragm (1) is formed by injection molding of a thermoplastic resin as a main material. A rib group (15) composed of a plurality of concentric ring-shaped ribs (15a, 15b, 15c, 15d-) is provided on the back surface of (1), and one of the rib groups (15) is used as a guide for a voice coil bobbin ( An inverted dome type speaker characterized in that 2) is fixed to the diaphragm (1). 2. A ring-shaped throat (22) is arranged between the voice coil bobbin (2) and another rib of the rib group (15). Dome speaker. 3. The oscillating plate (1) is an olefin resin,
Alternatively, the inverted dome type speaker according to claim 1 or 2, which is made of a mixture of an olefin resin and a reinforcing material. 4. The inverted dome type speaker according to claim 3, wherein the reinforcing material mixed with the olefin resin is 20 to 50% by weight of flake natural mica or artificial mica having an aspect ratio of 15 or more. .