WO2010095351A1

WO2010095351A1 - Speaker

Info

Publication number: WO2010095351A1
Application number: PCT/JP2010/000315
Authority: WO
Inventors: 大沼岳人; 北村肇
Original assignee: スター精密株式会社
Priority date: 2009-02-20
Filing date: 2010-01-21
Publication date: 2010-08-26
Also published as: CN102273225A; JP2010193352A

Abstract

The thickness of an electrodynamic speaker equipped with a voice coil of an approximately rectangular roll shape is reduced, and the acoustic characteristics thereof are improved. A plate member (24) is bonded to the upper side of a diaphragm (12), the plate member (24) covering a central region located inside the inner periphery of the voice coil (14). Thus, the height-direction space necessary over the central region is rendered small and the rigidity of the region is enhanced. This plate member (24) comprises a carbon-fiber-reinforced sheet obtained by infiltrating a resin into band-shaped bundles of unidirectionally extending carbon fiber filaments and curing the resin. Consequently, compared to the case where a carbon-fiber-reinforced sheet comprising plain-weave carbon fibers was bonded, the central region is made to have a lighter weight and the height-direction space necessary thereover is made smaller. The plate member is disposed so that the direction in which the carbon fiber filaments extend is the same as the direction in which the minor sides of the peripheral edge (24a) of the plate member (24) extend. The rigidity of the central region is thereby sufficiently ensured.

Description

Speaker

The present invention relates to a so-called electrodynamic speaker, and particularly to a speaker including a voice coil having a substantially rectangular winding shape.

In general, an electrodynamic speaker includes a diaphragm, a voice coil fixed to the lower surface of the diaphragm, a magnetic circuit unit in which a magnetic gap for accommodating the lower end of the voice coil is formed, and the magnetic circuit unit and the diaphragm. And a frame for fixing and supporting the outer peripheral edge portion.

At that time, “Patent Document 1” describes such an electrodynamic speaker provided with a voice coil having a substantially rectangular winding shape.

JP 2007-60463 A

By adopting a speaker having a voice coil having a substantially rectangular winding shape as described above, the outer shape of the speaker can be easily set to be substantially rectangular. Therefore, space efficiency when this speaker is mounted on an external device such as a cellular phone can be improved.

By the way, in general, it is desirable that the acoustic characteristics of a speaker be a broadband characteristic.

That is, in the sound pressure level frequency characteristic of the speaker shown in FIG. 3, it is desirable to make the high resonance frequency Fh as high as possible while making the lowest resonance frequency Fo as low as possible. At that time, in order to increase the high frequency resonance frequency Fh, it is necessary to increase the rigidity of the central region located on the inner peripheral side of the voice coil in the diaphragm as much as possible.

For this reason, in the conventional speaker, the central region of the diaphragm is formed so as to swell in a dome shape, thereby improving the rigidity.

However, as described in the above-mentioned “Patent Document 1”, when the voice coil has a substantially rectangular winding shape, the peripheral shape of the central region of the diaphragm is not circular. There is a problem that even if the central region is expanded in a dome shape, its rigidity cannot be sufficiently increased.

Further, when the central region of the diaphragm is formed so as to swell in a dome shape as described above, a space in the height direction is required correspondingly, so that there is a problem that the speaker cannot be thinned.

In the speaker described in “Patent Document 1”, the central region of the diaphragm and the peripheral region thereof are configured by separate members in order to enhance the acoustic characteristics. In this case, the central region is the peripheral region. It is comprised with the member whose rigidity is higher than. However, since the members constituting the central region and the peripheral region are all members made of resin, there is a limit in increasing the rigidity of the members.

On the other hand, it is conceivable that an aluminum plate covering the central region is joined to the upper surface of the diaphragm. In such a case, it is possible to increase the rigidity of the central region of the diaphragm and reduce the required space in the height direction to reduce the thickness of the speaker. However, in this case, there is a problem that the sound pressure of the speaker is lowered because the weight of the central region of the diaphragm becomes considerably large.

Also, instead of an aluminum plate, a structure in which carbon fiber reinforced sheets obtained by plain weaving of carbon fibers are joined may be considered. In such a case, it is possible to reduce the weight of the diaphragm while increasing the rigidity of the central region of the diaphragm. However, in such a case, there is a problem that the required space in the height direction of the central region of the diaphragm cannot be sufficiently suppressed, and therefore the speaker cannot be effectively thinned.

The present invention has been made in view of such circumstances, and in an electrodynamic speaker provided with a voice coil having a substantially rectangular winding shape, the acoustic characteristics are improved after achieving a reduction in thickness. An object of the present invention is to provide a speaker capable of achieving the above.

In the present invention, the plate member is joined to the central region of the diaphragm, and the above object is achieved by devising the structure of the plate member.

That is, the speaker according to the present invention is
A diaphragm, a voice coil fixed to the lower surface of the diaphragm, a magnetic circuit unit in which a magnetic gap for accommodating the lower end of the voice coil is formed, and the magnetic circuit unit and the outer peripheral edge of the diaphragm are fixedly supported. A speaker comprising:
The voice coil has a substantially rectangular winding shape,
On the upper surface of the diaphragm, a plate member having a substantially rectangular outer shape that covers a central region located on the inner peripheral side of the voice coil in the diaphragm is joined,
This plate member is composed of a carbon fiber reinforced sheet obtained by impregnating a resin into a band-like bundle of carbon fiber filaments extending in a single direction and curing the resin.
This carbon fiber reinforced sheet is formed so that the direction in which the carbon fiber filament extends is substantially matched with the direction in which the short side portion of the outer peripheral edge of the plate member extends.

In the above configuration, the terms indicating the directionality such as “lower surface” and “lower end” are used for convenience in order to clarify the positional relationship between members constituting the speaker. The directionality when used for is not limited.

The specific joining means for “joining” the plate member to the upper surface of the diaphragm is not particularly limited, and for example, adhesion, thermocompression bonding, insert molding, or the like can be employed.

The above-mentioned “carbon fiber reinforced sheet” may be one in which a band-like bundle of carbon fiber filaments is arranged in a single layer, or is arranged in a plurality of layers so as to align the direction of the bundle. Also good.

The type of carbon fiber constituting the “carbon fiber filament” is not particularly limited, and for example, PAN-based carbon fiber, pitch-based carbon fiber, or the like can be used.

As shown in the above configuration, the speaker according to the present invention is configured as an electrodynamic speaker. However, since the voice coil has a substantially rectangular winding shape, the outer shape of the speaker is also substantially omitted. It can be easily set to a rectangle. As a result, space efficiency when the speaker is mounted on an external device such as a mobile phone can be improved.

Moreover, since the plate member which covers the center area | region located in the inner peripheral side rather than the voice coil is joined to the upper surface of a diaphragm, the speaker which concerns on this invention joins the center area | region of a diaphragm to the dome shape like before. As compared with the case where the diaphragm is formed so as to swell, the rigidity of the central region of the diaphragm can be increased, and the required space in the height direction can be suppressed to be small, so that the speaker can be thinned.

In this case, the plate member has a substantially rectangular outer shape, and this plate member is a carbon fiber reinforced sheet obtained by impregnating a resin into a band-like bundle of carbon fiber filaments extending in a single direction and curing it. Therefore, the following operational effects can be obtained.

That is, as compared with the case where an aluminum plate is used as the plate member, the weight can be significantly reduced, and thereby the sound pressure of the speaker can be increased. Further, as compared to the case where a carbon fiber reinforced sheet in which carbon fibers are plain woven is used as the plate member, the central region of the diaphragm can be further reduced in weight, so that the sound pressure of the speaker is further increased. In addition, since the required space in the height direction of the central region of the diaphragm can be further reduced, the speaker can be made thinner more effectively.

Moreover, the carbon fiber reinforced sheet constituting the plate member is formed so that the direction in which the carbon fiber filaments extend is substantially coincident with the direction in which the short side portion of the outer peripheral edge of the plate member extends. Despite the fact that the carbon fiber filament extends in a single direction, the rigidity of the central region of the diaphragm to which the plate member is joined can be sufficiently secured. And thereby, the rigidity of the center area | region of a diaphragm can be made into the thing close | similar to the rigidity at the time of the carbon fiber reinforcement sheet | seat formed by plain-weaving carbon fiber being joined.

Therefore, according to the present invention, it is possible to improve the acoustic characteristics of the electrodynamic speaker provided with the diaphragm having a substantially rectangular outer shape while reducing the thickness thereof.

In the above configuration, if the plate member is arranged so that the outer peripheral edge is positioned directly above the upper end surface of the voice coil, the rigidity of the central region of the diaphragm is improved, and then the voice coil The winding diameter can be ensured to the maximum, whereby the sound pressure of the speaker can be maximized.

In this case, “directly above the upper end surface of the voice coil” means that the outer peripheral edge of the plate member is located within the range of the width of the upper end surface of the voice coil.

Side sectional view which shows the speaker which concerns on one Embodiment of this invention in the state arrange | positioned upwards II direction view of FIG. Sound pressure level frequency characteristics diagram showing the acoustic characteristics of a typical speaker The figure which shows the sound pressure level frequency characteristic of the speaker which concerns on the said embodiment with two comparative examples. The figure which shows the sound pressure level frequency characteristic at the time of replacing with the structure of the said embodiment and forming the center area | region of a diaphragm in the dome shape. The figure which shows the sound pressure level frequency characteristic at the time of replacing with the composition of the above-mentioned embodiment, and joining the plate made from aluminum

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view showing a speaker 10 according to an embodiment of the present invention in an upwardly arranged state, and FIG. 2 is a view taken in the direction of arrow II in FIG.

As shown in these drawings, the speaker 10 according to the present embodiment is a small electrodynamic speaker, and is used in a state of being mounted on an external device such as a mobile phone. The speaker 10 has a substantially rectangular outer shape in plan view, and the width in the long side direction is set to a value of about 20 mm and the width in the short side direction is set to a value of about 15 mm.

The speaker 10 includes a diaphragm 12, a voice coil 14 fixed to the lower surface of the diaphragm 12, a frame 16 that fixes and supports the outer peripheral edge of the diaphragm 12, and a magnetic gap that houses the lower end of the voice coil 14. A magnetic circuit unit 18, a cover 20 that covers the diaphragm 12 from above, a pair of terminal members 22 fixed to the frame 16, and a plate member 24 joined to the upper surface of the diaphragm 12. It has become.

The diaphragm 12 has a substantially rectangular outer shape slightly smaller than the outer shape of the speaker 10. The diaphragm 12 is formed by subjecting a synthetic resin film such as a polyimide film to hot press molding. The diaphragm 12 includes a central plane portion 12A formed in a planar shape, an upper bulge portion 12B extending in a substantially rectangular ring shape with an upward arcuate cross-sectional shape so as to surround the central plane portion 12A, and the upper bulge portion 12B. The central plane portion 12A and the outer peripheral plane portion 12C formed to be flush with the central plane portion 12A.

The winding shape of the voice coil 14 is set to be substantially rectangular in plan view. The voice coil 14 is fixed to the diaphragm 12 by bonding at the outer peripheral edge portion of the central flat surface portion 12A (that is, in the vicinity of the inner peripheral side of the upper bulging portion 12B). The voice coil 14 is electrically connected to a pair of terminal members 22 via a pair of coil terminals (not shown) extending from the voice coil 14.

The frame 16 is an injection molded product made of synthetic resin, and is arranged so as to surround the magnetic circuit unit 18. The frame 16 has a substantially rectangular outer shape in plan view, and a substantially rectangular opening 16a is formed at the center thereof. A diaphragm support portion 16b for fixing and supporting the outer peripheral plane portion 12C of the diaphragm 12 is formed on the inner peripheral portion of the upper end surface of the frame 16 in a step-down manner.

The magnetic circuit unit 18 is an internal magnetic type magnetic circuit unit, and includes a substantially box-shaped base 28 surrounding the voice coil 14, a magnet 30 bonded and fixed to the upper surface of the bottom wall of the base 28, and the magnet 30. And a yoke 32 fixedly adhered to the upper surface. In the magnetic circuit unit 18, the magnetic gap is formed between the inner surface of the peripheral wall of the base 28 and the outer peripheral surface of the yoke 32. A notch 28 a is formed at each corner of the base 28.

The magnetic circuit unit 18 is adhesively fixed to the frame 16 while being fitted from below into the opening 16a of the frame 16.

The cover 20 is an injection molded product made of synthetic resin, and has substantially the same outer shape as the frame 16 in a plan view. The cover 20 has sound emitting holes 20a at a plurality of locations. The cover 20 is bonded and fixed to the upper end surface of the frame 16 at the outer peripheral edge.

The pair of terminal members 22 includes a pair of land portions 22A formed integrally with the frame 16 by insert molding, and a pair of coil springs 22B protruding downward from the frame 16. The pair of land portions 22 </ b> A are formed so as to be exposed on the lower surface of one short side portion of the frame 16. Further, the pair of coil springs 22B are arranged at two corner portions on one short side portion side of the frame 16, and are electrically connected to an external device through these.

The plate member 24 is joined to the upper surface of the central plane portion 12A of the diaphragm 12. This joining is performed by adhesion using an epoxy adhesive or the like.

The plate member 24 is arranged so that its outer peripheral edge 24a is positioned directly above the upper end surface of the voice coil 14. The plate member 24 covers a central region located on the inner peripheral side of the diaphragm 12 with respect to the voice coil 14.

The plate member 24 is composed of a single-layer carbon fiber reinforced sheet obtained by impregnating a band-like bundle of carbon fiber filaments extending in a single direction and curing the resin. At this time, the thickness of the carbon fiber reinforced sheet is set to a value of 200 μm or less (for example, about 100 μm).

PAN-based carbon fiber is used as the carbon fiber constituting the carbon fiber filament. Further, as the resin impregnated in the band-like bundle of carbon fiber filaments, a thermosetting resin such as an epoxy resin is used.

This carbon fiber reinforced sheet is formed so that the direction in which the carbon fiber filaments extend matches the direction in which the short side portion of the outer peripheral edge 24a of the plate member 24 extends.

When the speaker 10 rings, the diaphragm 12 moves up and down the central flat surface portion 12A so that the upper bulging portion 12B is elastically deformed. At this time, even when the amplitude of the diaphragm 12 is maximized, the height position of the cover 20 is set so that the plate member 24 joined to the upper surface of the central plane portion 12A does not interfere with the cover 20. Is set.

4 to 6 are sound pressure level frequency characteristic diagrams showing the results of experiments conducted to confirm the operational effects of the present embodiment.

In this experiment, sound pressure was measured at a distance of 10 cm from each speaker with a baffle plate disposed around each speaker.

FIG. 4 is a diagram showing sound pressure level frequency characteristics of the speaker 10 according to the present embodiment together with two comparative examples.

In the same figure, the graph shown by the thick solid line is the direction in which the carbon fiber filaments of the carbon fiber reinforced sheet constituting the plate member 24 extend when the direction of the carbon fiber filaments is 0 ° (that is, as in this embodiment, It is a characteristic view of the case where the short side part in the outer periphery 24a of the plate member 24 corresponds with the extending direction.

On the other hand, in the figure, the graph shown by a thin solid line is when the direction of the carbon fiber filament is 90 ° (that is, the direction in which the carbon fiber filament extends is orthogonal to the direction in which the short side portion extends). FIG.

Further, in the figure, a graph indicated by a solid line of medium thickness indicates that the direction of the carbon fiber filament is 45 ° (that is, the direction in which the carbon fiber filament extends is 45 with respect to the direction in which the short side portion extends). It is a characteristic diagram of the case of tilting.

Comparing these three graphs, when the direction of the carbon fiber filament is 0 °, the high frequency resonance frequency Fh becomes the highest, and as the direction of the carbon fiber filament becomes 45 ° and 90 °, the high frequency resonance frequency Fh. Is low. This is considered to be because when the direction of the carbon fiber filament is 0 °, the length of the carbon fiber filament is the shortest, and thereby the rigidity of the carbon fiber reinforced sheet (that is, the plate member 24) is the highest. .

However, in any of these cases, a carbon fiber reinforced sheet obtained by impregnating a resin into a band-like bundle of carbon fiber filaments extending in a single direction and curing is used, so the three graphs shown in FIG. The sound pressures in the frequency region lower than the region resonance frequency Fh are substantially the same value.

FIG. 5 is formed such that the central region of the diaphragm 12 swells in a dome shape instead of the configuration in which the plate member 24 is joined to the upper surface of the central plane portion 12A of the diaphragm 12 as in this embodiment. It is a figure which shows the sound pressure level frequency characteristic in a case.

Although the rigidity of the diaphragm 12 can be increased somewhat by expanding the central area of the diaphragm 12 in this way, the peripheral area of the central area of the diaphragm 12 is not a circle but a substantially rectangular shape, so that the rigidity is sufficiently high. I can't do it. Therefore, even with such a configuration, as shown in the figure, the high-frequency resonance frequency Fh cannot be increased so much. However, since the weight of the diaphragm 12 can be kept small by expanding the central region of the diaphragm 12 in a dome shape, the sound pressure in the frequency region lower than the high frequency resonance frequency Fh can be increased as shown in FIG. it can.

FIG. 6 shows that the plate member 24 is joined to the upper surface of the central plane portion 12A of the diaphragm 12 as in this embodiment, and an aluminum plate having the same size as the plate member 24 is joined. It is a figure which shows the sound pressure level frequency characteristic at the time of setting.

Since the rigidity of the central region of the diaphragm 12 can be increased by using the aluminum plate in this way, the high frequency resonance frequency Fh can be increased as shown in FIG. However, when an aluminum plate is used, the weight of the central region of the diaphragm 12 becomes considerably large. Therefore, as shown in the figure, the sound pressure in the frequency region lower than the high frequency resonance frequency Fh is It will decline.

In that respect, like the speaker 10 according to the present embodiment, a plate member 24 made of a carbon fiber reinforced sheet having a carbon fiber filament direction of 0 ° is joined to the upper surface of the central plane portion 12A of the diaphragm 12. As a result, the high frequency resonance frequency Fh can be increased, and the sound pressure in a frequency region lower than the high frequency resonance frequency Fh can be increased.

As described above in detail, the speaker 10 according to the present embodiment is configured as an electrodynamic speaker 10, but the voice coil 14 has a substantially rectangular winding shape. The outer shape can be easily set to a substantially rectangular shape. As a result, space efficiency when the speaker 10 is mounted on an external device such as a cellular phone can be improved.

Further, in the speaker 10 according to the present embodiment, the plate member 24 covering the central region located on the inner peripheral side of the voice coil 14 is joined to the upper surface of the central plane portion 12A of the diaphragm 12. Thus, as compared with the case where the central region of the diaphragm 12 is formed so as to swell in a dome shape, the rigidity of the central region of the diaphragm 12 can be increased and the necessary space in the height direction can be reduced. Then, the height position of the cover 20 can be lowered by that amount, whereby the speaker 10 can be thinned.

At this time, the plate member 24 has a substantially rectangular outer shape, and the plate member 24 is a carbon fiber obtained by impregnating a band-like bundle of carbon fiber filaments extending in a single direction and curing the resin. Since the reinforcing sheet is used, the following operational effects can be obtained.

That is, as compared with the case where an aluminum plate is used as the plate member 24, the weight can be significantly reduced, and thereby the sound pressure of the speaker 10 can be increased.

Further, as compared with the case where a carbon fiber reinforced sheet in which carbon fibers are plain woven is used as the plate member 24, the central region of the diaphragm 12 is further reduced in weight by the thickness difference. Thus, the sound pressure of the speaker 10 can be further increased. Further, since the required space in the height direction of the central region of the diaphragm 12 can be further reduced by the thickness difference, the speaker 10 can be made thinner more effectively.

In addition, the carbon fiber reinforced sheet constituting the plate member 24 is formed so that the direction in which the carbon fiber filament extends is coincident with the direction in which the short side portion of the voice coil 14 extends. However, the rigidity of the central region of the diaphragm 12 to which the plate member 24 is joined can be sufficiently secured. Thereby, the rigidity of the central region of the diaphragm 12 can be made close to the rigidity in the case of a configuration in which a carbon fiber reinforced sheet obtained by plain weaving of carbon fibers is joined.

Therefore, according to the present embodiment, in the electrodynamic speaker 10 including the diaphragm 12 having a substantially rectangular outer shape, the acoustic characteristics can be improved while the thickness is reduced.

In addition, in the present embodiment, the plate member 24 is arranged so that the outer peripheral edge 24a thereof is positioned directly above the upper end surface of the voice coil 14, so that the rigidity of the central region of the diaphragm 12 is improved. Thus, the winding diameter of the voice coil 14 can be ensured to the maximum, whereby the sound pressure of the speaker 10 can be increased to the maximum.

In the above embodiment, the plate member 24 has been described as being bonded to the upper surface of the central plane portion 12A of the diaphragm 12, but the plate member 24 is thermocompression bonded to the upper surface of the central plane portion 12A of the diaphragm 12. Alternatively, the above-described joining may be performed by insert molding the diaphragm 12 using the plate member 24 as an insert member.

In the above embodiment, the carbon fiber reinforced sheet constituting the plate member 24 has been described as having a configuration in which a band-like bundle of carbon fiber filaments is arranged in a single layer. Even when the layers are arranged so as to be aligned, if the thickness is set in the same manner as in the above-described embodiment, the same effects as those in the above-described embodiment can be obtained.

Furthermore, in the said embodiment, although demonstrated as what uses PAN-type carbon fiber as carbon fiber which comprises the said carbon fiber filament, it is also possible to use pitch-type carbon fiber etc.

Moreover, in the said embodiment, although demonstrated as what uses thermosetting resins, such as an epoxy resin, as resin impregnated to the said strip | belt-shaped bundle of the carbon fiber filament, it is also possible to use resin materials other than this. Is possible.

It should be noted that the numerical values shown as specifications in the above embodiment are merely examples, and it is needless to say that these may be set to different values as appropriate.

DESCRIPTION OF SYMBOLS 10 Speaker 12 Diaphragm 12A Center plane part 12B Upper bulging part 12C Outer peripheral plane part 14 Voice coil 16 Frame 16a Opening part 16b Diaphragm support part 18 Magnetic circuit unit 20 Cover 20a Sound emission hole 22 Terminal member

22A Land part

22B Coil spring 24 Plate member 24a Outer peripheral edge 28 Base 28a Notch 30 Magnet 32 York

Claims

A diaphragm, a voice coil fixed to the lower surface of the diaphragm, a magnetic circuit unit in which a magnetic gap for accommodating the lower end of the voice coil is formed, and the magnetic circuit unit and the outer peripheral edge of the diaphragm are fixedly supported. A speaker comprising:
The voice coil has a substantially rectangular winding shape,
On the upper surface of the diaphragm, a plate member having a substantially rectangular outer shape that covers a central region located on the inner peripheral side of the voice coil in the diaphragm is joined,
This plate member is composed of a carbon fiber reinforced sheet obtained by impregnating a resin into a band-like bundle of carbon fiber filaments extending in a single direction and curing the resin.
The speaker, wherein the carbon fiber reinforced sheet is formed so that a direction in which the carbon fiber filament extends substantially coincides with a direction in which a short side portion of the outer peripheral edge of the plate member extends.
2. The speaker according to claim 1, wherein the plate member is disposed so that an outer peripheral edge of the plate member is positioned right above the upper end surface of the voice coil.