This invention relates to flat speakers of full-face driving and, in particular, to a flat speaker of full-face driving adapted to ultra-thinning of small loudspeakers employed as mounted to portable or mobile telephones, notebook or lap-top personal computers and the like.
As the small loudspeaker mounted to the mobile telephones, lap-top personal computers and the like, such small dynamic loudspeaker having inner-magnet type magnetic circuit as shown in
Now, the mobile telephones have been developed more and more in the multiplicity of types and functions, whereas still further minimization in the dimensions and weight has been demanded in view of the convenience of portability, and necessarily the small loudspeakers mounted thereto have been strongly demanded to be also small and ultra-thin.
Since such general dynamic loudspeaker as shown in
On the other hand, there has been known old such flat speaker of full-face driving as shown in
In the small loudspeakers mounted to mobile telephones and the like, the conventional small loudspeaker of general dynamic type is unable to respond to the demand of minimization to be ultra-thin.
Since it is difficult to have both of the small and light-weight type as well as the sufficient sound pressure and wide band reproduction satisfied, the conventional flat speaker of full-face driving is not suitable for use as the small loudspeaker in the mobile telephone and lap-top personal computer.
The present invention has been suggested in view of such respects, and its object is to easily provide a flat speaker of full-face driving capable of realizing the sufficient sound pressure and wide-band reproduction even being the ultra-thin type, and responding to severe needs of the mobile telephone and the like.
In order to solve the above problem, the flat speaker of full-face driving of the present invention which comprising a plurality of magnets disposed to have magnetized directions mutually reversed in adjacent ones of the magnets or a plurality of magnetic gaps constituted to have magnetic flux directions mutually reversed in adjacent ones of the magnetic gaps, and a planar diaphragm, is characterized in that the plurality of magnets or the plurality of magnetic gaps are formed with respect to a frame comprised of a magnetic member, the plurality of magnets being respectively in similar or homothetic annular shape and disposed concentrically mutually with constant spacings maintained, and that the magnetic gaps for inserting therein a plurality of voice coils provided on the planar diaphragm are constituted within the spacings without provision of any magnetic member above the plurality of magnets or the plurality of magnetic gaps.
Further, the flat speaker of full-face driving of the present invention is characterized in that the plurality of voice coils are made by winding a conducting wire a plurality of times to be vertically stacked in a direction parallel with the thickness direction of the magnets.
Further, the flat speaker of full-face driving of the present invention is characterized in that the plurality of voice coils are connected, for at least two or more, in series, parallel or series-parallel connection.
Further, the flat speaker of full-face driving of the present invention is characterized in that the planar diaphragm is provided with ribs.
Further, the flat speaker of full-face driving of the present invention is characterized in that a yoke or yokes are arranged in place of the magnets mutually reversed in the direction of magnetization, so as to be reversed with each other in the direction of flux of adjacent ones of the magnetic gaps.
a) and 1(b) are diagrams showing an arrangement of the flat speaker of full-face driving in an embodiment of the present invention, in which
a) and 3(b) are diagrams showing an arrangement of the flat speaker of full-face driving in another embodiment of the present invention, in which
a) and 4(b) are diagrams showing an arrangement of the flat speaker of full-face driving in another embodiment of the present invention, in which
a) and 5(b) are diagrams showing an arrangement of the flat speaker of full-face driving in another embodiment of the present invention, in which
a) and 7(b) are to show a basic arrangement of conventional flat speaker of full-face driving, in which
The flat speaker of full-face driving according to the present invention eliminates the magnetic member on the magnet which has hindered the thickness minimization of the magnetic circuit, and constitutes the magnetic circuit with the magnets arranged to render the magnetized direction of adjacent ones of the magnets to be opposite to each other.
With the elimination of the magnetic member on the magnets, any increase in the reactance of the voice coil due to the presence of the magnetic member is excluded, and an improvement is attained in respect of the defect that the loudspeaker unit is deteriorated in the high frequency range by the magnetic member.
Further, a plurality of annular magnets are concentrically arranged and, in addition, the voice coils are constituted, instead of a plane printed wiring, but by means of conducting wires three-dimensionally wound into a vertical stack lying in the thickness direction of the magnets, with which arrangement the magnetic flux can be more efficiently utilized for improvement in the conversion efficiency.
In the followings, embodiments of the present invention shall be described to details with reference to the drawings.
a) and 1(b) are diagrams showing an arrangement of the flat speaker of full-face driving in an embodiment of the present invention, wherein
The present embodiment is of the flat speaker of full-face driving of such ultra-thin type as about 25(W)×25(L)×2(H) mm, and employing four annular magnets 5 and three annular voice coils 2. In the planar diaphragm 1, radial and annular ribs 7 are formed.
On a frame 4 of a magnetic member, four annular magnets 5a–5d are arranged so as to mutually maintain constant spacings 6. Voice coils 2 are of the conducting wire wound annular for a plurality of times into the vertical stacks. The planar diaphragm 1 provided with the voice coils 2 is mounted into the frame 4 through a gasket 3.
Adjacent ones of the magnets 5a–5d are magnetized to be mutually in reverse direction. That is, in the sectioned view of
A zone in which the magnetic flux gathers dense in each spacing 6 is the magnetic gap, in which each of the voice coils 2 is respectively inserted. Since no magnetic member is disposed on the magnets 5, the height of the magnetic circuits can be reduced by that extent, and this can be contributive to the minimization in the thickness and weight of the loudspeaker. Further, in contrast to with any narrow magnetic gap formed by the magnetic member normally disposed on the magnet, it is possible to make the gap wider, which lowers the possibility of the coil's hitting other members. Since no magnetic member is present nearby the voice coils 2, further, there is no increase in the reactance of the magnetic member. Therefore, it is possible to restrain the increase in the impedance of the loudspeaker in the high frequency range.
Since the plurality of magnets 5 are arranged annular and, in correspondence thereto, the plurality of voice coils 2 are also arranged annular, the voice coils are made to intersect the magnetic flux over the entire circumference, so as to eliminate any ineffective part of the coils in contrast to such conventional parallel arrangement of bar-shaped magnets as shown in
While the annular magnets of such appearance as shown in
For the plurality of voice coils 2, further, either one of air-core coil and bobbin-wound coil will be applicable but, from the view point of the minimization in weight and so on, the air-core coil will be advantageous.
Further, the nominal impedance of the loudspeaker can be set optionally by means of series, parallel or series-parallel connection of the plurality of voice coils 2.
Since the ribs are formed in the planar diaphragm 1 to elevate the rigidity, any application of tension is no more required as in the case of conventional full-face driving type flat tweeter in mounting the planar diaphragm 1 to the frame 4, so as to be able to improve the workability and to obtain a loudspeaker of stable performance also in view of the acoustic characteristics.
It has been confirmed that the reproduction of sufficient broad band and sound pressure level for use in the mobile telephone and lap-top personal computer can be obtained.
Other embodiment than that of
Adjacent ones of the magnets 34a–34c are mutually reversed in the direction of magnetization. That is, in the sectioned view of
According to the present embodiment, similar to the embodiment of
Further according to the flat speaker of full-face driving of the present embodiment, similar to the embodiment of
Next, the description shall be made with reference to other embodiment than those of
In the present embodiment, adjacent ones of the magnetic gaps are mutually reversed in the direction of magnetic flux. That is, in the sectioned view of
According to the present embodiment, similar to the embodiment of
According to the flat speaker of full-face driving, further, it is possible to attain the wide band reproduction and sound pressure level sufficient for the use in the mobile telephones and lap-top personal computers, similar to the embodiment of
Next, the description shall be made to other embodiment than those of
In the present embodiment, the adjacent ones of the magnetic gaps are reversed to each other in the direction of magnetic flux. That is, in the sectioned view of
According to the present embodiment, the diaphragm 36 does not require such application of tension as in the conventional full-face driving type flat tweeter for mounting the diaphragm to the frame 33, similar to the embodiments of
Further, it has been confirmed that, according to the flat speaker of full-face driving of the present embodiment, the wide band reproduction and sound pressure level sufficient for the use in the mobile telephones and lap-top personal computers can be obtained, similar to the embodiment of
As has been described in the forgoing, the flat speaker of full-face driving of the present invention which comprises a plurality of magnets disposed to have magnetized directions mutually reversed in adjacent ones of the magnets, and a planar diaphragm, is characterized in that the plurality of the magnets are formed with respect to a frame comprised of a magnetic member respectively in similar or homothetic annular shape, as disposed concentrically mutually with constant gaps maintained, the magnetic gaps are formed in the spacing for inserting therein a plurality of voice coils provided on the planar diaphragm without provision of any magnetic member above the plurality of magnets, whereby the ultra-thickness minimization of the small loudspeakers mounted in the mobile telephones, lap-top personal computers and so on is made possible, and a full-range, flat speaker of full-face driving capable of obtaining the sufficient sound pressure level and wide band reproduction even being the ultra-thin type can be obtained.
Further, the workability in the mounting step of the diaphragm can be improved by the provision of the ribs to the planar diaphragm to elevate the rigidity, the manufacture is made easier, and it becomes possible to obtain stable and uniform performance.
Further, as the flat speaker of full-face driving of the present invention employs the yokes in place of the magnets mutually reversed in the direction of magnetization, it is possible to reduce the manufacturing costs.
Number | Date | Country | Kind |
---|---|---|---|
2001-220999 | Jul 2001 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP02/06170 | 6/20/2002 | WO | 00 | 1/22/2004 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO03/010997 | 2/6/2003 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4334127 | Shimada | Jun 1982 | A |
Number | Date | Country |
---|---|---|
30 24732 | Jun 1980 | DE |
2 055 013 | Jun 1980 | GB |
51-21816 | Feb 1976 | JP |
S51-21816 | Feb 1976 | JP |
S54-107236 | Jul 1979 | JP |
56-7593 | Jan 1981 | JP |
S56-142197 | Oct 1981 | JP |
S58-4309 | Mar 1983 | JP |
1-106700 | Apr 1989 | JP |
09-224297 | Aug 1997 | JP |
2000-152378 | Jun 2000 | JP |
2000-253489 | Sep 2000 | JP |
Number | Date | Country | |
---|---|---|---|
20040202347 A1 | Oct 2004 | US |