JP6667364B2 - Flat speaker and method for improving its frequency characteristics - Google Patents

Description

  The present invention relates to a flat speaker that reproduces a sound source by vibrating a diaphragm, and a method of improving the frequency characteristics thereof.

  2. Description of the Related Art A flat speaker that reproduces a sound source by vibrating a planar diaphragm is known. The flat speaker generally has a configuration in which a flat frame, a permanent magnet plate, a nonwoven fabric sheet, a plane diaphragm, a nonwoven fabric sheet, a permanent magnet plate, and a flat frame are sequentially stacked. The plane diaphragm is an FPC (Flexible Printed Circuits) in which a predetermined pattern (voice coil) is printed and wired. When the voice coil is energized, it faces each other across the nonwoven fabric sheet by electromagnetic force according to Fleming's left hand rule. It vibrates in the plate thickness direction between a pair of arranged permanent magnet plates. A sound wave generated by the vibration (that is, a reproduced sound obtained by reproducing a sound source) is radiated to the outside and is heard by a listener. For example, Patent Literature 1 describes a specific configuration of this type of flat speaker.

  In a general cone speaker, since the impedance characteristic increases as the frequency becomes higher, the sound pressure level in the higher frequency is greatly reduced. On the other hand, since the flat speaker does not have an increase in impedance characteristics in a high frequency range, the sound pressure level does not decrease as compared with the cone speaker. In this regard, the flat speaker is advantageous for reproducing a sound source including a high-frequency range such as high-resolution audio.

Japanese Patent No. 3192372

  However, even with a flat speaker, a decrease in sound pressure level in a high frequency range cannot be avoided. In order to achieve high reproduction performance for sound sources including high-frequency ranges, it is necessary to further suppress the decrease in sound pressure level in the high frequency range even for flat speakers (improve the sound pressure level in the high frequency range compared to conventional models). Is desired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for improving frequency characteristics (particularly, a sound pressure level in a high frequency range) and a flat speaker having improved frequency characteristics. That is.

A flat speaker according to one embodiment of the present invention includes a flat diaphragm on which a wiring pattern forming a voice coil is printed and wired . The diaphragm has a cover material that covers the wiring pattern. In this flat speaker, the thickness of the diaphragm is different for each region because the thickness of the cover member is different for each region.

  In one embodiment of the present invention, the diaphragm may be configured to include a first region having a reference thickness and at least one second region having a thickness smaller than the first region.

  Further, in one embodiment of the present invention, the cover material covers the wiring pattern in the first region and the second region has an opening, so that the second region does not cover the wiring pattern. It may be.

  In one embodiment of the present invention, the wiring pattern may be plated in a second region not covered with the cover material.

  Further, the flat speaker according to the embodiment of the present invention may have a shape drawn out from the diaphragm and include a drawer portion in which a terminal for connecting a wiring pattern to an external circuit is formed. In this case, the wiring pattern and the terminal are formed on a common base material of the diaphragm and the lead portion, and the wiring pattern is covered at the opening of the diaphragm on the opposite side of the base material with the wiring pattern and the terminal therebetween. The terminal is not covered with the cover material, and the terminal is not covered with the cover material and is exposed at the drawer portion.

  In one embodiment of the present invention, the cover material has a first thickness that covers the wiring pattern in the first region and a first thickness that covers the wiring pattern in the second region. It may be configured to have a second cover material having a smaller thickness and a second thickness.

  Further, in one embodiment of the present invention, the cover material may be configured to include a cover portion covering the entire area of the wiring pattern, and a sticking portion stuck on the cover portion. The attaching unit may be attached only to the first region.

  In one embodiment of the present invention, the second region has, for example, a circular shape or an elliptical shape having a major axis in a direction orthogonal to a direction in which the wiring pattern extends.

  In one embodiment of the present invention, the second region is located, for example, substantially at the center of the diaphragm.

  In one embodiment of the present invention, there may be a plurality of second regions, and each of the second regions may be located at a peripheral portion of the diaphragm.

Furthermore, the method according to an embodiment of the present invention, in the flat diaphragm which a wiring pattern is printed circuit to form a voice coil, a cover member for covering the wiring pattern formed in different thicknesses for each region, the vibration This is a method of improving the frequency characteristics of a flat loudspeaker by varying the thickness of the plate for each region .

  According to one embodiment of the present invention, there is provided a method for improving frequency characteristics (particularly, sound pressure level in a high frequency range) and a flat speaker having improved frequency characteristics.

1 is an external perspective view showing the external appearance of a flat speaker according to an embodiment of the present invention. 1 is an exploded perspective view illustrating a configuration of a flat speaker according to an embodiment of the present invention. It is the front view and side sectional view of the plane diaphragm provided in the flat speaker concerning one embodiment of the present invention. It is the front view and side sectional view of the plane diaphragm provided in the flat speaker concerning the 1st modification of the present invention. It is the front view and side sectional view of the plane diaphragm provided in the flat speaker concerning the 2nd modification of the present invention. It is a figure explaining the method of reducing the weight of a plane diaphragm. It is a figure explaining the method of reducing the weight of a plane diaphragm. It is a figure explaining the method of reducing the weight of a plane diaphragm.

  Hereinafter, a flat speaker according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view showing the external appearance of a flat speaker 1 according to one embodiment of the present invention. As shown in FIG. 1, the flat loudspeaker 1 is a thin, substantially rectangular parallelepiped thin speaker in appearance. The flat speaker 1 is a full digital speaker that is directly driven by a digital sound source by a digital signal processing technique such as Dnote (registered trademark), and is mounted on an electronic device such as a thin television or a headphone.

  FIG. 2 is an exploded perspective view showing the configuration of the flat speaker 1 according to one embodiment of the present invention. As shown in FIG. 2, the flat loudspeaker 1 has a plane diaphragm 10, a pair of permanent magnet plates 20 opposed to each other at a predetermined interval across the plane diaphragm 10, and a pair of permanent magnet plates 20. And a metal housing (front cover 30 and back plate 40) housed therein and fixedly supported therein, and a nonwoven fabric sheet 50 interposed between the planar diaphragm 10 and each permanent magnet plate 20.

  The plane diaphragm 10 is a substantially rectangular FPC on which a voice coil 10aa made of a meandering copper foil pattern is printed and wired on at least one surface. The base film and the coverlay of the plane diaphragm 10 are formed of a flexible insulating resin film such as a polyethylene terephthalate film or an aromatic polyimide film, for example.

  The flat speaker 1 is configured to be driven by a multi-voice coil, that is, a plurality of voice coils in order to secure sound pressure and achieve high-quality sound reproduction while being driven at a low voltage. Therefore, a plurality of voice coils (meandering copper foil pattern) 10aa are printed and wired on the planar diaphragm 1. In the drawings, a plurality of voice coils 10aa wired in a meandering shape are shown by one pattern for convenience.

  The permanent magnet plate 20 has a substantially flat plate shape having a size similar to that of the planar diaphragm 10, and is formed of, for example, a resin magnet or rubber magnet containing ferrite or rare earth magnetic powder. The permanent magnet plate 20 has a multi-pole magnetized pattern in the form of parallel stripes in which strip-shaped N-poles and S-poles appear alternately over the entire surface facing the plane diaphragm 10. In the multipolar magnetization patterns of the pair of permanent magnet plates 20, the north poles and the south poles face each other with the plane diaphragm 10 (and the nonwoven fabric sheet 50) interposed therebetween.

  On the multi-pole magnetized pattern surface of the permanent magnet plate 20 on which the multi-pole magnetized pattern is formed, the vicinity of each boundary between the N pole and the S pole is called a neutral zone, and is adjacent to each other so as to straddle the neutral zone. A magnetic field from the matching north pole to the south pole is formed. That is, a magnetic field is formed along the surface of the planar diaphragm 10.

  The permanent magnet plate 20 has a plurality of circular sound emission holes 20a penetrating the permanent magnet plate 20 at appropriate positions (for example, in a staggered lattice) on each neutral zone.

  The plane diaphragm 10 has a configuration in which the linear portion of the voice coil 10aa (the linear portion extending in the Y-axis direction in the drawing) corresponds to the neutral zone of each permanent magnet plate 20 (specifically, the linear portion of the voice coil 10aa). A positional relationship with the pair of permanent magnet plates 20 is set so that the portion extends in a direction crossing the magnetic field.

  The front cover 30 is a metal component having a high magnetic permeability such as an iron plate, and has a substantially rectangular parallelepiped shape with one surface opened. The permanent magnet plate 20 is tightly fixed to the inner surface of the front cover 30 by its own magnetic attraction. Similar sound emission holes 30a are also formed in the front cover 30 at positions corresponding to the respective sound emission holes 20a of the permanent magnet plate 20. The permanent magnet plate 20 may be fixed to the inner surface of the front cover 30 with an adhesive in addition to its own magnetic attraction.

  The back plate 40 is also a metal component having a high magnetic permeability such as an iron plate, and has a substantially rectangular parallelepiped shape with one surface opened. The permanent magnet plate 20 is also tightly fixed to the inner surface of the back plate 40 by its own magnetic attraction. A similar sound emission hole 40a is formed in the back plate 40 at a position corresponding to each sound emission hole 20a of the permanent magnet plate 20. The permanent magnet plate 20 may be fixed to the inner surface of the back plate 40 with an adhesive in addition to its own magnetic attraction.

  The front cover 30 has a plurality of locking claws 30b. Further, cuts 40b are formed in the rear plate 40 at positions corresponding to the locking claws 30b. The front cover 30 and the back plate 40 are fixed by locking the locking claws 30b with the cuts 40b, and a flat, substantially rectangular parallelepiped metal housing is completed.

  FIGS. 3A and 3B are a front view and a side sectional view (sectional view taken along line AA of FIG. 3A) of the planar diaphragm 10 according to one embodiment of the present invention, respectively. As shown in FIG. 3, the planar diaphragm 10 is composed of a base film 10b, a copper foil pattern (voice coil 10aa and terminals 10ab described later) formed on the base film 10b, and a cover lay 10c covering the copper foil pattern. The FPC includes a substantially rectangular portion 10A that is a diaphragm main body portion, and a drawn portion 10B that is drawn out of the substantially rectangular portion 10A.

  A meandering wiring pattern (voice coil 10aa) forming a magnetic circuit is formed on the base film 10b in the roughly rectangular portion 10A. The general rectangular portion 10A is housed in a metal housing formed by the front cover 30 and the back plate 40, at a position between a pair of permanent magnet plates 20 (more precisely, a pair of nonwoven fabric sheets 50). . The movement of the plane diaphragm 10 in the XY directions (the plate surface direction of the plane diaphragm 10) is substantially restricted by the inner wall surface of the metal housing.

  A terminal (copper foil pattern) 10ab is formed on the base film 10b in a state where the terminal (copper foil pattern) 10ab is exposed from the cover lay 10c at the tip of the drawn portion 10B drawn out of the metal housing. Note that a reinforcing film may be attached to the base film 10b on the rear side surface of the leading end of the lead portion 10B (the portion where the terminal 10ab is formed).

  The voice coil 10aa has its input / output end connected to the terminal 10ab via a lead pattern formed in the lead portion 10B, and is energized by a current supply circuit connected to the terminal 10ab.

  When the voice coil 10aa is energized, the plane diaphragm 10 is moved between the pair of permanent magnet plates 20 (more precisely, the pair of nonwoven fabric sheets 50) in the Z-axis direction (plane) by electromagnetic force according to Fleming's left hand rule. It vibrates in the thickness direction of the diaphragm 10). Sound waves generated by the vibration (that is, reproduced sounds obtained by reproducing the sound source) are radiated outside from the sound wave emission holes of the permanent magnet plate 20 and the front cover 30 and from the sound wave emission holes of the permanent magnet plate 20 and the back plate 40. , Will be heard by the listener. The flat speaker 1 can reproduce a digital sound source with high sound quality because the sound quality does not deteriorate due to the conventional analog conversion or the like.

  In the present embodiment, by reducing a part of the shape of the cover lay 10c to reduce its weight, the general rectangular portion 10A which is the diaphragm main body is lightened. In other words, by reducing the thickness of a part of the general rectangular portion 10A with respect to the reference thickness, the general rectangular portion 10A is reduced in weight. Specifically, as shown in FIG. 3, a hole is formed in the central region of the general rectangular portion 10A of the coverlay 10c (a circular opening 10ca is formed), so that the general rectangular portion 10A is reduced in weight. ing. By reducing the weight of the general rectangular part 10A, the electromagnetic force required to vibrate the general rectangular part 10A is suppressed to a small value, and the gain in a high frequency range is improved.

  As described above, according to the present embodiment, a frequency characteristic with a high sound pressure level in a high frequency range can be obtained as compared with a configuration in which the general rectangular portion 10A is not reduced in weight.

  The formation of the opening 10ca locally changes the rigidity of the substantially rectangular portion 10A, so that resonance is suppressed and a frequency characteristic closer to flat is obtained.

  In addition, by forming the opening 10ca, high-frequency components are concentrated and output from around the opening 10ca. For this reason, the effect that the treble range stands out from the viewpoint of hearing can be obtained. As the opening 10ca is made smaller, the treble components are concentrated and output from around the opening 10ca, so that the treble is more prominent. On the other hand, as the opening 10ca is made larger, the treble components are not concentrated and are dispersed and output. As a result, the sense of spaciousness of the sound increases.

  Further, since the opening 10ca is formed, the voice coil 10aa is not covered by the coverlay 10c and is exposed in the opening 10ca. Therefore, rust of the voice coil 10aa is concerned. Therefore, the voice coil 10aa in the opening 10ca is plated (for example, gold plated) for rust prevention.

  In addition, since the strength of the voice coil 10aa in the opening 10ca is reinforced by performing the above-described plating, the rigidity of the entire rectangular portion 10A is increased as compared with the case where the plating is not performed. Accordingly, the roughly rectangular portion 10A easily vibrates finely, which is advantageous for improving the gain in a high frequency range. That is, as a secondary effect of performing the above plating process, it is possible to obtain a frequency characteristic with a higher sound pressure level in a high frequency range.

  As the size of the opening 10ca increases, the weight of the general rectangular portion 10A can be reduced. On the other hand, there is a concern that the rigidity of the general rectangular portion 10A lowers, thereby lowering the sound pressure level in a high frequency range. Thus, the size of the opening 10ca may be determined in consideration of the balance between the extension of the high frequency range (sound pressure level in the high frequency range) and the feeling of sound expansion.

  The above is the description of the exemplary embodiment of the present invention. The embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiments of the present application also include examples and the like exemplarily shown in the specification or contents obtained by appropriately combining obvious examples and the like.

  In the following, the same or similar components as those of the flat speaker 1 according to the above-described embodiment will be denoted by the same or similar reference numerals, and description thereof will be appropriately simplified or omitted.

  FIGS. 4A and 4B are a front view and a side cross-sectional view (BB cross-sectional view of FIG. 4A) of the planar diaphragm 10M1 according to the first modification of the present invention, respectively. is there.

  As shown in FIG. 4, in the first modified example, a total of four openings 101ca are formed in the peripheral portion (four corners) of the general rectangular portion 10A. According to the first modified example, by forming a plurality of relatively small openings 101ca, the output of the high-frequency range component is appropriately dispersed while the low rigidity of the roughly rectangular portion 10A is moderately suppressed. (A sound pressure level in a high frequency range) and a feeling of sound spread can be achieved at a high level. In addition, since the local change in rigidity of the substantially rectangular portion 10A becomes complicated, resonance can be further suppressed and a flat frequency characteristic can be obtained.

  FIGS. 5A and 5B are a front view and a side sectional view (a CC sectional view of FIG. 5A) of a planar diaphragm 10M2 according to a second modified example of the present invention, respectively. is there.

  As shown in FIG. 5, in the second modification, an opening 101ca is formed at the center of the general rectangular portion 10A. The opening 101ca according to the second modification has an elliptical shape having a major axis in a direction orthogonal to the direction in which the voice coil 10aa extends. By forming the elliptical opening 101ca in such a direction, the number of the voice coils 10aa exposed from the coverlay 10c can be reduced (for example, when the opening 101ca is formed in a circular shape or in a direction in which the voice coil 10aa extends). (Compared to the case of an elliptical shape having a major axis in the direction), so that the lowering of the rigidity of the substantially rectangular portion 10A due to the formation of the opening 101ca is suitably suppressed. Therefore, it is possible to obtain a frequency characteristic having a higher sound pressure level in a high frequency range.

  Note that the shape of the opening 101ca is not limited to a circular shape or an elliptical shape, and may be, for example, an I shape, an L shape, a polygonal shape, or the like.

  In the above-described embodiment, in order to reduce the weight of the general rectangular portion 10A, a part of the region of the general rectangular portion 10A has an opening shape. However, the method of reducing the weight of the general rectangular portion 10A is not limited thereto. 6 to 8 illustrate another method for reducing the weight of the general rectangular portion 10A.

  In the example of FIG. 6, the voice coil 10aa is covered with the coverlay 10c having the reference thickness in principle, but only a part of the area (for example, the area corresponding to the opening 101ca in the above embodiment) is It is covered with another thinner coverlay 10c1.

  In the example of FIG. 7, the entire area of the voice coil 10aa is covered with the coverlay 10c2 having a thickness smaller than the reference, and only a part of the area (for example, the area other than the opening 101ca in the above-described embodiment) is covered. A sheet 10c3 is attached on 10c2 by bonding or the like. The sheet 10c3 is, for example, the same material as the cover lay 10c2. For example, the reference thickness is the total of the coverlay 10c2 and the sheet 10c3.

  In the example of FIG. 8, the entire area of the voice coil 10aa is covered by the coverlay 10c4. The coverlay 10c4 has a reference thickness in principle, but only a part of the area (for example, an area corresponding to the opening 101ca in the above-described embodiment) is thinner than this (in FIG. 8, the arrow indicates a finger). Area).

  In any of the examples of FIGS. 6 to 8, since the thickness of a part of the coverlay is formed smaller than the reference, the weight of the general rectangular portion 10A is reduced. Therefore, a frequency characteristic with a high sound pressure level in a high frequency range is obtained. Further, since the coverlay is formed over the entire area of the general rectangular portion 10A, the rigidity of the general rectangular portion 10A can be suitably suppressed, and the plating process on the voice coil 10aa becomes unnecessary.

REFERENCE SIGNS LIST 1 flat speaker 10 plane diaphragm 10aa voice coil 10ab terminal 10b base film 10c coverlay 10ca opening 10A roughly rectangular portion 10B drawer 20 permanent magnet plate 20a sound emission hole 30 front cover 30a sound emission hole 30b locking claw 40 back plate 40a Sound emission hole 40b Cut 50 Non-woven fabric sheet

Claims (20)

It has a flat diaphragm on which the wiring pattern forming the voice coil is printed and wired ,
The diaphragm,
Having a cover material for covering the wiring pattern,
By the thickness of the cover member is different for each region, the thickness of the diaphragm is different for each of the areas,
Flat speaker. The diaphragm,
A first region having a standard thickness,
At least one second region having a thickness smaller than the first region;
Having,
The flat speaker according to claim 1. The cover material,
Covering the wiring pattern with the first region,
Since the second region is an opening, the second region does not cover the wiring pattern,
The flat speaker according to claim 2. The wiring pattern is
Plated in a second area not covered by the cover material,
The flat speaker according to claim 3 . A lead portion having a shape pulled out from the diaphragm and having a terminal formed to connect the wiring pattern and an external circuit is provided,
The wiring pattern and the terminals are formed on a common base material of the diaphragm and the lead portion,
On the opposite side of the base material across the wiring pattern and the terminal, the wiring pattern is not covered with the cover material at the opening of the diaphragm, and the terminal is covered with the cover material at the lead portion. Not exposed,
The flat speaker according to claim 3 or 4 . The cover material,
A first cover material having a first thickness covering the wiring pattern in the first region,
A second cover material having a second thickness, which is smaller than the first thickness and covers the wiring pattern in the second region,
Having,
The flat speaker according to claim 2. The cover material,
A cover portion covering the entire area of the wiring pattern,
An attaching portion attached on the cover portion,
Including
The sticking unit,
Affixed only to the first area,
The flat speaker according to claim 2. The second area,
A circular shape or an elliptical shape having a major axis in a direction orthogonal to a direction in which the wiring pattern extends,
The flat speaker according to any one of claims 3 to 7 . The second area,
Located substantially at the center of the diaphragm,
The flat speaker according to any one of claims 3 to 8 . The second region is plural,
Each of the second regions is located at a peripheral portion of the diaphragm,
The flat speaker according to any one of claims 3 to 8 . In a flat diaphragm on which a wiring pattern forming a voice coil is printed and wired , a cover material covering the wiring pattern is formed with a different thickness for each region, and the thickness of the diaphragm is made different for each region. To improve the frequency characteristics of a flat speaker. The diaphragm has a configuration including a first region having a reference thickness and at least one second region having a thickness smaller than the first region,
A method for improving the frequency characteristic of the flat speaker according to claim 11 . The second region has an opening shape for the cover material,
A method for improving the frequency characteristics of the flat speaker according to claim 12 . Plating the wiring pattern in a second region not covered with the cover material,
A method for improving the frequency characteristics of the flat speaker according to claim 13 . The wiring pattern formed on the base material in the diaphragm is covered with the cover material,
A terminal for connecting the wiring pattern and an external circuit is formed on a common base material with the diaphragm in a drawer portion having a shape pulled out from the diaphragm,
On the opposite side of the base material with the wiring pattern and the terminal interposed therebetween, the wiring pattern is not covered with the cover material in the opening-shaped portion of the diaphragm, and the terminal is formed of the cover material in the lead portion. Uncovered and exposed,
A method for improving the frequency characteristics of the flat speaker according to claim 13 or 14 . The cover material, a first cover material having a first thickness covering the wiring pattern in the first region, and a second thinner than the first thickness covering the wiring pattern in the second region. And a second cover material having a thickness of
A method for improving the frequency characteristics of the flat speaker according to claim 12 . The cover material has a configuration including a cover portion that covers the entire area of the wiring pattern, and an attachment portion attached on the cover portion,
The attaching unit is attached only to the first area,
A method for improving the frequency characteristics of the flat speaker according to claim 12 . The second region is a circular region or an elliptical region having a major axis in a direction perpendicular to a direction in which the wiring pattern extends,
A method for improving the frequency characteristic of a flat speaker according to any one of claims 13 to 17 . The second region is located substantially at the center of the diaphragm,
A method for improving the frequency characteristics of a flat speaker according to any one of claims 13 to 18 . The second region is plural,
Positioning each of the second regions at the periphery of the diaphragm,
A method for improving the frequency characteristics of a flat speaker according to any one of claims 13 to 18 .

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