JP2010251816A - Thin acoustic electromechanical transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin acoustic electromechanical transducer providing excellent acoustic characteristics compared to a conventional one by preventing the flopping of a vibration plate. <P>SOLUTION: A flat speaker 10 as this thin acoustic electromechanical transducer includes: a vibration film 12 of a structure where a coil is formed tightly on a thin film having flexibility; a pair of permanent magnets 18 and 20 arranged oppositely to the vibration film 12; and a front cover 22 and a back plate 24 as a housing for holding them. When a current flows to the coil, mechanical force along the thickness direction of the vibration film 12 acts on the coil according to the Fleming's left-hand rule. The vibration film 12 vibrates in association with the coil, and thereby acoustic waves are generated. The vibration film 12 is fixed to the housing through terminal boards 62, 64 arranged at two upper and lower parts. Thereby, flopping when the vibration film 12 vibrates is prevented, and an excellent acoustic characteristic is provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin acoustoelectric mechanical converter, and in particular, a vibration film having a structure in which a coil is formed in close contact with a flexible thin film, and is provided to face the vibration film and crosses the extending direction of the coil. A magnet plate that generates a magnetic field, and a casing that holds the diaphragm and the magnet plate, and one of the current flowing through the coil and the mechanical force acting on the coil along the thickness direction of the diaphragm The present invention relates to a thin-type acousto-electromechanical converter that converts to

  Conventionally, as this type of thin acousto-electrical transducer, there is a flat speaker (flat speaker) disclosed in Patent Document 1, for example. The flat speaker includes a permanent magnet plate, a vibration film disposed so as to face the permanent magnet plate, a buffer member interposed between the permanent magnet plate and the vibration film, and a relative position of the vibration film with respect to the permanent magnet plate. And a support member that regulates. On the surface of the permanent magnet plate on the side facing the vibration film, a parallel striped multipolar magnetized pattern in which strip-like N poles and S poles alternately appear is formed over the entire surface. Of the multipolar magnetization pattern surfaces, there is basically no magnetic field in the direction perpendicular to the multipolar magnetization pattern surface near the boundary between the N and S poles. The area near the pole is called the neutral zone. On the other hand, the vibration membrane is a structure in which a coil made of a meandering conductor pattern is printed on a thin and flexible resin film, and the linear portion of the conductor pattern hits a position corresponding to the neutral zone of the permanent magnet plate. Is provided. Furthermore, the vibration film is supported by a support member so that only displacement in the in-plane direction is restricted and can be freely displaced in the thickness direction. The shock-absorbing member is flexible and breathable and has a structure in which sheets having substantially the same size as the vibration film are stacked, and between the sheet and the permanent magnet plate or between the sheet and the vibration film. Are arranged so that a gap is formed between them.

  According to the flat speaker configured in this way, the magnetic lines of force pass in a direction perpendicular to the straight portion of the coil (conductive wire pattern). For this reason, when a drive current is supplied to the coil, a mechanical force (electromagnetic force) along the thickness direction of the diaphragm acts on the coil in accordance with Fleming's left-hand rule. Then, the vibration film (resin film) is vibrated in the thickness direction accompanying the coil, and as a result, sound waves are generated. That is, in order to generate the sound wave, conversion from electrical energy called drive current to mechanical energy called mechanical force is performed. On the other hand, the conventional technology can be applied to conversion from mechanical energy to electrical energy and, in short, to a microphone.

JP-A-9-331596

  By the way, although not explicitly shown in the above-described prior art, both ends of the coil are usually connected to terminals fixed to the casing of the flat speaker. In addition, this terminal is provided at a single location in the prior art from the viewpoint of ease of connection with external wiring and appearance design. However, when the terminals are provided at one location, the vibrating membrane including the coil is fixed to the housing at the one location. Then, when the vibrating membrane vibrates, this one place serves as a fulcrum, and the vibrating membrane is violently fluttered, that is, flutters. This fluttering is not preferable because it adversely affects the acoustic characteristics.

  Therefore, an object of the present invention is to provide a thin acousto-electromechanical transducer that can obtain better acoustic characteristics than conventional ones by eliminating the fluttering of the vibrating membrane.

  In order to achieve this object, the present invention provides a vibrating membrane having a structure in which a coil is formed in close contact with a flexible thin film, and a magnetic field that is provided opposite to the vibrating membrane and crosses the extending direction of the coil. A magnet plate to be generated and a casing for holding the diaphragm and the magnet plate are converted from one of the current flowing through the coil and the mechanical force acting on the coil along the thickness direction of the diaphragm. A thin acoustoelectric mechanical converter is assumed. Under this premise, a pair of terminals of the coil are provided at two positions which are substantially line symmetric with respect to a certain straight line and are substantially point symmetric with respect to a certain point on the straight line. A processing unit is provided. The pair of terminal processing units of the coil are connected to terminals fixed to the housing in correspondence with each of the terminal processing units.

  According to the present invention configured as described above, the magnetic field across the extending direction of the coil is generated from the magnet plate. Here, for example, it is assumed that a current flows through the coil. Then, according to Fleming's left-hand rule, a mechanical force along the thickness direction of the diaphragm acts on the coil. Then, the vibration film (thin film) is vibrated in the thickness direction along with the coil, and as a result, a sound wave is generated. That is, in order to generate the sound wave, conversion from electrical energy called current to mechanical energy called mechanical force is performed, and in short, a speaker is realized. On the other hand, it is assumed that a mechanical force acts on the vibrating membrane when a sound wave hits the vibrating membrane. Then, the vibration film vibrates along the thickness direction, and accordingly, the coil also vibrates. As a result, current flows through the coil according to Fleming's right-hand rule. That is, conversion from mechanical energy acted on by sound waves to electrical energy is performed, and in short, a microphone is realized.

  By the way, in the present invention, a pair of coils is provided at two locations which are side edge portions of the vibration film and are substantially line symmetric with respect to a certain straight line and are substantially point symmetric with respect to a certain point on the straight line. Terminal processing units, for example, both ends of the coil are provided. Then, both ends of the coil are connected to terminals fixed to the housing corresponding to the respective ends. That is, the diaphragm including the coil is fixed to the housing at the two locations. This fixed state is balanced. Therefore, when the vibrating membrane vibrates, the above-described fluttering is prevented.

  In the present invention, an even number of coils may be formed. In this case, each coil has a first terminal portion at one end and a second terminal portion at the other end. And the relationship between the electric current which flows between the 1st terminal part of each coil and the 2nd terminal part, and the mechanical force which acts on the said each coil shall be common between each coil. For example, it is assumed that a mechanical force in a certain direction acts on a certain coil when a current flows from the first terminal portion to the second terminal portion of the certain coil. Then, even when a current flows from the first terminal portion of another coil toward the second terminal portion, the mechanical force in the same direction acts on the other coil. In addition, for example, when a mechanical force is applied to the vibrating membrane due to a sound wave hitting the vibrating membrane, currents in the same direction flow through all the coils. In such a relationship, for each coil, the first terminal portion is provided at one of the two locations described above, and the second terminal portion is provided at the other of the two locations. In addition, it is assumed that the numbers of the first terminal unit and the second terminal unit are the same between these two places. Furthermore, a terminal is provided corresponding to each of all the first terminal units and all of the second terminal units.

  According to this structure, the usage mode (variation) of the thin acousto-electrical transducer of the present invention becomes rich and flexible. For example, when only one thin acousto-electric transducer is used, all the coils may be connected in series. Specifically, on one side of the two locations described above, a terminal connected to the first terminal portion of one of the coils and a terminal connected to the second terminal portion of another coil are connected to the external wiring. As for the other terminals, those connected to an arbitrary first terminal unit and those connected to an arbitrary second terminal unit are connected to each other. On the other side of the two locations, for all the terminals, the one connected to the arbitrary first terminal unit and the one connected to the arbitrary second terminal unit are connected to each other. Thereby, since one long coil is formed, high conversion efficiency is obtained. In addition, since the connections between the terminals are performed at close proximity to each other, the operation is easy and simple.

  Further, for example, when a plurality of thin acousto-electric transducers are used, all the coils may be connected in series between the plurality of thin acousto-electric transducers. Specifically, for each thin acousto-electrical transducer, the terminal connected to the first terminal part of one of the coils and the second terminal part of another coil on one side of the above-described two locations. For all terminals except the connected terminals, those connected to an arbitrary first terminal unit and those connected to an arbitrary second terminal unit are connected to each other. Similarly, on the other side of the two places, all terminals except for a terminal connected to the first terminal part of one of the coils and a terminal connected to the second terminal part of another coil Are connected to an arbitrary first terminal unit and connected to an arbitrary second terminal unit. Among the terminals that are not connected between one side of the two locations described above in a certain thin acoustoelectric transducer and the other side of the two locations in another thin acoustoelectric transducer. The one connected to the first terminal portion and the one connected to the second terminal portion are connected to each other. A similar connection is made between all thin acoustoelectric transducers. However, for one thin acousto-electrical transducer, two unconnected terminals are connected on one side of the two places. In addition, with regard to another thin acoustoelectric machine converter, external wiring is connected to two terminals that are not connected on the other side of the two places. As a result, all the coils are connected in series between the plurality of thin acoustoelectric transducers, in other words, the thin acoustoelectric transducers are connected in series to form a so-called array. In addition, the connection between the thin acousto-electrical transducers is made between the terminals located close to each other, so that the operation is easy and simple.

  The present invention is suitable for a speaker. In particular, a loudspeaker with a large diaphragm is more suitable. That is, when the vibration film is fixed at one place as in the above-described prior art, the larger the vibration film, the easier the above-described fluttering occurs. The present invention is extremely effective for a loudspeaker having a large vibration film that easily generates flutter.

  When the present invention is applied to a speaker, the coil may have a protruding portion that protrudes in a direction crossing its own extending direction. By providing such a protrusion on the coil, the adhesion between the coil and the thin film at the portion where the protrusion is provided increases. This means that the responsiveness of the thin film that vibrates with the coil is improved in the portion where the protrusion is provided. On the other hand, in the portion where the protrusion is provided, the weight increases by the amount of the protrusion, which also affects the responsiveness. In other words, the provision of the protrusion changes the response of the entire diaphragm, and consequently the acoustic characteristics of the entire speaker. In other words, the protrusion functions as a control unit that controls the acoustic characteristics of the entire speaker. Since no current flows through the protrusion, the protrusion does not have a special effect on the current flowing through the coil.

  Furthermore, when a communication path that connects the space in which the vibration film exists and the external space is provided, it is desirable that a protrusion is provided in accordance with the communication path. That is, the communication path referred to here functions as a sound wave emission path for emitting sound waves generated by the vibration of the vibrating membrane toward the external space. Therefore, the effectiveness of the projecting portion becomes more remarkable by providing the projecting portion according to the communication path functioning as such a sound wave emission path.

  As described above, according to the present invention, the vibrating membrane including the coil is fixed in a balanced state at two locations. Therefore, unlike the related art that generates a flutter because the vibration film is fixed at one place, the flutter is prevented. Therefore, better acoustic characteristics than before can be obtained.

It is a figure which shows schematic structure of the planar speaker which concerns on one Embodiment of this invention. It is an assembly drawing of the same planar speaker. It is an illustration figure which shows schematic structure of the diaphragm in the same plane speaker. It is an illustration figure which shows the fixed state of the vibration film. It is an illustration figure which shows the usage condition of the same plane speaker. It is an illustration figure which shows the use aspect different from FIG. It is an illustration figure which shows the fixed state of the diaphragm in the prior art as an object for comparison of this embodiment. It is an illustration figure which shows another example of the prior art. FIG. 4 is an illustrative view showing a vibrating membrane in a mode different from FIG. 3. FIG. 10 is an illustrative view showing a vibrating membrane in a further different mode from FIG. 9. FIG. 11 is an illustrative view showing a vibrating membrane in a further different mode from FIG. 10.

  An embodiment of the flat speaker 10 to which the present invention is applied will be described below.

  As shown in FIG. 1, the flat speaker 10 according to the present embodiment has a flat, substantially rectangular parallelepiped shape in appearance. And, structurally, as can be seen from the assembly diagram shown in FIG. 2, one vibration film 12 and two buffer members 14 and 16 provided so as to sandwich both surfaces of the vibration film 12, It consists of two permanent magnet plates 18 and 20 provided so as to sandwich these buffer members 14 and 16 from the outside, and a front cover 22 and a back plate 24 as a casing.

  As shown in FIG. 3, the vibration film 12 includes a substantially rectangular thin film 26, and meandering coils 28 and 30 formed on the front surface and the back surface of the thin film 26, respectively. Among these, the thin film 26 is a flexible resin film having a thickness of about 30 [μm], for example. Examples of such a resin film include a polyethylene terephthalate film and an aromatic polyimide film. In addition, concave notches 32 and 34 are provided at the centers of the upper and lower edges of the thin film 26.

  On the other hand, the coils 28 and 30 are copper foil patterns with a thickness dimension of 20 [μm] to 50 [μm] formed by, for example, a printed wiring technique, and are in a conjugate relationship with each other. Specifically, one end of the coil 28 on the front surface side, for example, the upper end portion 36 in FIG. 3A is a plus terminal as a first terminal portion, and the plus terminal 36 is an upper notch 32. It is provided in the vicinity of the side edge. The other end 38 of the coil 28 on the front side is a minus terminal as a second terminal portion, and the minus terminal 38 is provided in the vicinity of the side edge of the notch 34 on the lower side. On the other hand, one end of the coil 30 on the back side, for example, the upper end 40 in FIG. 3B is a minus terminal as the second terminal portion, and the minus terminal 40 It is provided near the side edge of the notch 32. The other end 42 of the coil 30 on the back side is a plus terminal as a first terminal portion, and this plus terminal 42 is provided in the vicinity of the side edge of the notch 34 on the lower side. Further, the linear portion provided in a large number so as to extend along the horizontal direction in the coil 28 on the front side, and the many linear portions provided in the same manner in the coil 30 on the back side include the thin film 26. It overlaps with each other. The positive terminal 36 of the front coil 28 and the negative terminal 40 of the rear coil 30 are opposed to each other with the upper cutout 32 interposed therebetween, and the negative terminal 38 of the front coil 28. The plus terminal 42 of the coil 30 on the back side is opposed to each other across the notch 34 on the lower side.

  According to this conjugate relationship, for example, a current flows from the positive terminal 36 of the front coil 28 to the negative terminal 38 and a current flows from the positive terminal 42 of the rear coil 30 to the negative terminal 40. These currents flow in the same direction in the respective linear portions. When a current flows from the minus terminal 38 of the coil 28 on the front side toward the plus terminal 36 and also when a current flows from the minus terminal 40 of the coil 30 on the back side toward the plus terminal 42, these currents are , Each straight portion flows in the same direction. Further, the positive terminal 36 of the coil 28 on the front side and the negative terminal 40 of the coil 30 on the back side are viewed as one terminal group, and the minus terminal 38 of the coil 28 on the front side and the coil 30 on the back side are shown. When the positive terminal 42 is viewed as one terminal group, these terminal groups are point-symmetric with respect to the center of the thin film 26. In addition, the terminal groups are line symmetric with respect to a straight line that passes through the center of the thin film 26 and is parallel to the straight portions of the coils 28 and 30. In short, these terminal groups are arranged in a well-balanced manner in each of the vertical and horizontal directions in FIG.

  Returning to FIG. 1 and FIG. 2, each of the buffer members 14 and 16 is a substantially rectangular sheet having substantially the same size as the vibrating membrane 12 (thin film 26), and is formed of a material having flexibility and air permeability. Yes. An example of such a material is a nonwoven fabric. Further, the buffer member 16 positioned on the back side of the vibration film 12 is provided with a notch 44 (the lower notch is not shown) similar to the vibration film 12 (thin film 26).

  Each of the permanent magnet plates 18 and 20 has an appropriate thickness, and each surface has a substantially flat plate shape slightly larger than the vibrating membrane 12. For example, a resin magnet or a rubber magnet containing ferrite or rare earth magnetic powder is used. Is formed by. Although not shown in the drawing, the above-described front side coil 28 is disposed on the surface of the permanent magnet plate 18 positioned on the front side of the vibration film 12 facing the vibration film 12 (with the buffer member 14 in between). A parallel striped multi-pole magnetized pattern in which N poles and S poles appear alternately along the alignment direction of the straight line portions is formed. More specifically, each boundary portion between each N-pole and each S-pole of the multipolar magnetization pattern surface is a neutral zone, and these neutral zones are opposed to each linear portion of the front side coil 28. In addition, the multipolar magnetization pattern is formed. Further, a plurality of through holes 46, 46,... Are provided at appropriate positions on each neutral zone so as to penetrate the permanent magnet plate 18 from the front side to the back side, for example, in a staggered pattern. . The configuration of the permanent magnet plate 18 including the multipolar magnetization pattern, the positional relationship between the multipolar magnetization pattern and the front coil 28, and the positions where the through holes 46, 46,. Since it is the same as that of the prior art (Patent Document 1), further detailed explanation is omitted.

  Similarly, for the permanent magnet plate 20 positioned on the back side of the vibration film 12, a multipolar magnetization pattern is formed on the surface facing the vibration film 12 (with the buffer member 16 in between). Specifically, the multipolar magnetization pattern is formed such that N poles and S poles appear alternately along the direction in which the straight portions of the back coil 30 are arranged. Each neutral zone of the back-side multipole magnetized pattern is opposed to each straight line portion of the back-side coil 30. Further, the back-side multipole magnetized pattern and the above-mentioned front-side multipole magnetized pattern sandwich the vibration film 12 (and the buffer members 14 and 16) and each other's N poles and S poles. Are formed so as to face each other. That is, the multipolar magnetized pattern is also conjugated with each other on the front side and the back side. A plurality of through holes 48, 48,... Are also provided on the neutral zones of the multipolar magnetization pattern on the back side so as to penetrate the permanent magnet plate 20 from the front side to the back side. . Further, concave notches 50 and 52 (see FIG. 1D in particular) are provided at the centers of the upper edge and the lower edge of the permanent magnet plate 20 in the same manner as the buffer member 16.

  The front cover 22 is made of a high permeability metal such as an iron plate, and all the components except the back plate 24 are accommodated in the internal space thereof. In particular, the front permanent magnet plate 18 is fixed to the inner surface of the front cover 22 by its magnetic attraction force. The front cover 22 is also provided with through holes 54, 54,... At positions facing the through holes 46, 46,. Further, a plurality of locking claws 58, 58,... That are locked to respective notches 56, 56,. Yes.

  The back plate 24 is also made of a high permeability metal, and the locking claws 58, 58,... Of the front cover 22 described above are locked to the notches 56, 56,. This completes the housing together with the front cover 22. In addition, the permanent magnet plate 20 on the back side is fixed to the inner side surface of the back plate 24 by the magnetic attractive force. At this time, a gap of a certain size, for example, a gap 59 of several [mm] is provided between the permanent magnet plate 20 on the back side and the permanent magnet plate 18 on the front side. The vibration film 12 and the buffer members 14 and 16 are interposed in the gap 59 with an appropriate margin (play). Further, the back plate 24 is also provided with through holes 60, 60,... At positions facing the through holes 48, 48,. Further, terminal blocks 62 and 64 are provided in the vicinity of the center of each of the upper edge and the lower edge of the back plate 24.

  Of these, the upper terminal block 62 is connected to the upper plus terminal 66 connected to the plus terminal 36 of the front coil 28 and the minus terminal 40 of the back coil 30 as shown in FIG. And an upper minus terminal 68. Note that these upper terminals 66 and 68 are both insulated from the back plate 24 and drawn to the outside (strictly, they are connected to the corresponding external terminals). The terminals 66 and 68 on the terminal block 62 side and the terminals 36 and 40 on the diaphragm 12 side are both connected by appropriate conductive wires such as wires. The copper foil patterns of the terminals 36 and 40 may be extended to the terminals 66 and 68 on the terminal block 62 side. In order to connect the terminals 66 and 68 on the terminal block 62 side and the terminals 36 and 40 on the diaphragm 12 side, the notch 50 is provided at the upper edge of the permanent magnet plate 20 on the back side as described above. In addition, a notch 44 is provided at the upper end edge of the buffer member 16 on the back side, and a notch 32 is provided at the upper end edge of the vibration film 12 (thin film 26).

  On the other hand, the lower terminal block 64 has a lower minus terminal 70 connected to the minus terminal 38 of the front coil 28 and a lower plus terminal 72 connected to the plus terminal 42 of the rear coil 30. is doing. These lower terminals 70 and 72 are both pulled out to the outside while being insulated from the back plate 24. The connection between the terminals 70 and 72 of the lower terminal block 64 and the terminals 38 and 42 on the vibrating membrane 12 side is also realized by an appropriate conductive line such as a wire. It may be realized by extending the copper foil patterns of the respective terminals 38 and 42 to the respective terminals 70 and 72 on the terminal block 64 side. Further, in order to connect the terminals 70 and 72 on the terminal block 64 side and the terminals 38 and 42 on the diaphragm 12 side, a notch 52 is provided at the lower end edge of the permanent magnet plate 20 on the back side, A notch portion (not shown) is provided at the lower end edge of the buffer member 16 on the back side, and a notch portion 34 is provided at the lower end edge of the vibration film 12 (thin film 26).

  When the flat speaker 10 configured in this way is used by only one unit, it is configured as shown in FIG. That is, the upper terminals 66 and 68 are connected to each other by an appropriate conductive wire 74 such as a covered cable. By doing so, as can be seen from FIG. 4 described above, the front side coil 28 and the back side coil 30 are connected in series with each other. The lower terminals 70 and 72 are connected to external wiring (not shown). That is, an audio signal is input between these terminals 70 and 72.

  When the audio signal is input in this way, currents according to the audio signal flow in the front side coil 28 and the back side coil 30 respectively. In particular, in the straight portions of the coils 28 and 30, the current flows in a direction perpendicular to the magnetic field. Then, according to Fleming's left-hand rule, a mechanical force along the thickness direction of the vibrating membrane 12 (thin film 26) acts on the coils 28 and 30 simultaneously. In addition, the direction in which this mechanical force acts is the same between the coils 28 and 30. That is, the coils 28 and 30 vibrate simultaneously and in the same direction. Then, accompanying the coils 28 and 30, the vibration film 12 vibrates. As a result, sound waves are generated. Specifically, for the front side, the through holes 46, 46,... Provided in the front permanent magnet plate 18 and the through holes 54, 54,. Sound waves are emitted to the outside. And with respect to the back side, each through-hole 48,48, ... provided in the said permanent magnet plate 20 of the said back side, and each through-hole 60,60, ... provided in the back plate 24 are passed. Sound waves are emitted to the outside.

  Further, when a plurality of, for example, two flat speakers 10 and 10 are used, the mode is as shown in FIG. In other words, as shown in FIG. 5, the upper terminals 66 and 68 of one flat speaker 10 are connected by an appropriate conductive line 74. The lower minus terminal 70 of the flat speaker 10 and the upper plus terminal 66 of another flat speaker 10 are connected by an appropriate conductive line 76. Further, the lower plus terminal 72 of the flat speaker 10 and the upper minus terminal 68 of another flat speaker 10 are connected by an appropriate conductive line 78. By doing so, all the coils 28, 28, 30 and 30 are connected in series between the flat speakers 10 and 10. In other words, an array speaker composed of two flat speakers 10 and 10 is realized. Then, external wirings (not shown) are connected to the lower terminals 70 and 72 that are not connected to the other flat speaker 10.

  In the embodiment shown in FIG. 6, the connection between the flat speakers 10 and 10 is made between one lower terminal 70 and 72 (terminal block 64) and the other upper terminal 66 and 68 (terminal block 66). The work is extremely easy and concise. Moreover, it is excellent also in design property. This is exactly the same when three or more planar speakers 10, 10,... Are connected.

  By the way, in this embodiment, as shown in FIG. 4, the vibrating membrane 12 is attached to the back plate 24, which is a housing, via the terminal blocks 62 and 64 at two locations on the upper end side and the lower end side. Fixed. The two fixed positions are point-symmetric with respect to the center of the vibration film 12 (thin film 26). In addition, the two places are line-symmetric with respect to a straight line that passes through the center of the vibration film 12 and extends in the horizontal direction. As a result, the vibrating membrane 12 is fixed to the housing 24 in a balanced state at the two locations.

  On the other hand, in the above-described prior art, for example, as shown in FIG. 7, the vibrating membrane 100 is fixed to the housing via one terminal block 102, that is, at one place. For this reason, in the related art, a flutter occurs when the vibrating membrane 100 vibrates. FIG. 7 illustrates the fixed state of the vibrating membrane 100 in an easy-to-understand manner following FIG. 4. In FIG. 7, only one coil is provided on one surface of the thin film 103 as the main body of the vibrating membrane 100. 104 is formed in close contact. Both ends 106 and 108 of the coil 104 are connected to two terminals 110 and 112 provided on the terminal block 102. Such a configuration is not clearly described in the prior art (Patent Document 1), but in the related art, a configuration similar to this is generally used.

  Also in the prior art, as shown in FIG. 8, for example, coils 120 and 122 may be formed on both surfaces of the vibration film 100 (thin film 103). However, in this case, in the prior art, one ends (upper end portions in FIG. 8) 124 and 126 of the coils 120 and 122 are connected to the terminals 110 and 112 of the terminal block 102. The other ends (lower ends in FIG. 8) of the coils 120 and 122 are connected to each other through the through hole 130. In other words, in the related art, even when the coils 120 and 122 are formed on both surfaces of the vibration film 100, the vibration film 100 is fixed to the casing only at one place. Therefore, fluttering still occurs.

  Further, in the conventional diaphragm 100 shown in FIG. 8, a through hole 130 is employed as means for connecting the coils 120 and 122 in series. However, the formation of the through hole 130 requires a corresponding cost. It takes. Therefore, when such a through hole 130 is formed, naturally, the manufacturing cost of the diaphragm 100 increases, and as a result, the price of the entire speaker increases. In addition, instead of the through hole 130, the coils 120 and 122 may be connected in series by an appropriate conductive wire such as a wire. In this case, the wire also vibrates with the vibrating membrane 100 together. Become. If it becomes so, the said wire will become an unwilling load with respect to the diaphragm 100, and may have a bad influence on an acoustic characteristic by extension.

  On the other hand, in the present embodiment, there is no need for the through hole 130 as shown in FIG. 8, and there is nothing that causes an unintentional load on the diaphragm 12. Also in this point, this embodiment is more advantageous than the conventional technology.

  As described above, according to the present embodiment, the vibrating membrane 12 is fixed to the housing 24 in a balanced state at two locations. Therefore, unlike the prior art, the vibrating membrane 12 does not flutter. Therefore, better acoustic characteristics than before can be obtained.

  In the present embodiment, the vibrating membrane 12 is displaced only in the thickness direction and not in the inner surface direction. This is because the peripheral edge of the vibration film 12 is regulated by the inner peripheral surface of the front cover 22. That is, the inner peripheral surface of the front cover 22 functions as a restricting unit that restricts (limits) displacement of the vibration film 12 toward the inner surface. On the other hand, in the above-described prior art, displacement of the vibration membrane toward the inner surface is restricted by inserting the support rods into the holes provided at the four corners of the vibration membrane (particularly, the conventional technology). Paragraph 0021). Also in the present embodiment, the displacement of the vibrating membrane 12 in the inner surface direction may be restricted in the same manner as in the conventional technique.

  In the present embodiment, a substantially rectangular shape is used as the vibrating membrane 12, but is not limited thereto. For example, a circular shape, an elliptical shape, a polygonal shape such as a hexagonal shape or an octagonal shape may be employed. However, the vibrating membrane 12 has a shape that can be fixed to the housing in a balanced manner at two locations, that is, has a portion that is point-symmetric with respect to its own center and is line-symmetric with respect to a straight line passing through the center. Those are preferred. Needless to say, when the shape of the vibrating membrane 12 changes, the respective shapes of the other constituent elements such as the permanent magnet plates 18 and 20 change accordingly.

  Further, in the present embodiment, the terminals 36, 38, 40 and 42 on the vibration film 12 side are connected to the terminals 66, 68, 70 and 72 on the terminal blocks 62 and 64 side, so that the vibration film is concerned. 12 is fixed to the casing 24 via the terminal blocks 62 and 64, but is not limited thereto. For example, the vibrating membrane 12 may be fixed to the housing 24 by another means such as a tape.

  As for the diaphragm 12, the front coil 28 is provided with x-shaped auxiliary patterns 80, 80,... As projections, for example, as shown in FIG. Patterns 80, 80,... May be provided. Among these, the front side auxiliary patterns 80, 80,... Are formed by a copper foil pattern together with the front side coil 28, and the respective positions are through holes 46 provided in the front side permanent magnet plate 18. , 46,... On the other hand, the auxiliary patterns 82, 82,... On the back side are also formed of a copper foil pattern together with the back side coil 30, and the respective positions are through holes 48 provided in the permanent magnet plate 20 on the back side. , 48,... .. And 82, 82,... Are provided so that the coil 28 and the thin film 26 are in close contact with each other in the portion where the associated patterns 80, 80,. Power increases. This means that in the portion where the associated patterns 80, 80,... And 82, 82,. On the other hand, in the portion where these attached patterns 80, 80, ... and 82, 82, ... are provided, the weight increases by the amount of the attached patterns 80, 80, ... and 82, 82, ... Also affects responsiveness. That is, by providing the auxiliary patterns 80, 80,... And 82, 82,..., The responsiveness of the entire vibrating membrane 12 changes, and consequently the acoustic characteristics of the entire flat speaker 10 change. In other words, the associated patterns 80, 80, ... and 82, 82, ... function as control means for controlling the acoustic characteristics of the entire flat speaker 10. Therefore, it is possible to obtain better acoustic characteristics by appropriately forming these auxiliary patterns 80, 80,... And 82, 82,. It is feared that the currents flowing through the coils 28 and 30 are affected by the provision of the attached patterns 80, 80,... And 82, 82,. However, since no current flows through the attached patterns 80, 80,... And 82, 82,.

  The attached patterns 80, 80,... And 82, 82,. Of course, other shapes such as a □ shape or a Δ shape may be used. Further, the shape of the associated patterns 80, 80,..., 82, 82,... May be changed depending on the location of the vibration film 12, and the size and number of the associated patterns 80, 80,. (Pitch) may be changed. In any case, the associated patterns 80, 80, ... and 82, 82, ... may be formed so as to obtain desired acoustic characteristics.

  In particular, as shown in FIG. 11, the front side accessory patterns 80, 80,... And the rear side accessory patterns 82, 82,. The following effects can be obtained. That is, as shown in FIG. 9 (or FIG. 10), when the accessory patterns 80, 80,... And 82, 82,. ... and 80, 80, ... and 82, 82, ... are different from each other in the mechanical strength of the vibrating membrane 12, and a weight difference is also produced. In this case, when the vibration film 12 vibrates, the vibration film 12 may be unintentionally distorted or bent, which may adversely affect the acoustic characteristics. On the other hand, in the configuration shown in FIG. 11, the front side accessory patterns 80, 80,... And the rear side accessory patterns 82, 82,. Therefore, the mechanical strength is uniform over the entire surface of the diaphragm 12, and the weight is uniform. Therefore, unintentional distortion and bending when the vibrating membrane 12 vibrates can be suppressed, and in particular, the unintentional distortion and bending in the longitudinal direction can be suppressed. This greatly contributes to obtaining good acoustic characteristics.

  Furthermore, in this embodiment, the coils 28 and 30 are formed on both surfaces of the vibration film 12 (thin film 26), but the present invention is not limited to this. For example, a coil may be formed only on one side of the vibrating membrane 12, or a plurality of coils, strictly speaking, an even number of coils may be formed on the one side. In addition, when coils are formed on both surfaces of the vibration film 12, a plurality of coils may be formed on each of the both surfaces. In this case, it is desirable that the number of coils be the same on both sides.

DESCRIPTION OF SYMBOLS 10 Planar speaker 12 Vibration membrane 18,20 Permanent magnet plate 22 Front cover 24 Back plate 26 Thin film 28,30 Coil 36,38,40,42 Terminal 62,64 Terminal block 66,68,70,72 terminal

Claims (5)

A vibrating membrane having a structure in which a coil is formed in close contact with a flexible thin film, a magnet plate that is provided opposite to the vibrating membrane and generates a magnetic field across the extending direction of the coil, and the vibrating membrane and the magnet plate A thin acousto-electromechanical transducer that converts from one of the current flowing through the coil and the mechanical force acting on the coil along the thickness direction of the vibrating membrane to the other,
A pair of terminal processing portions of the coil are respectively provided at two positions on the side edge portion of the vibration film that are substantially line-symmetric with respect to a certain straight line and are substantially point-symmetric with respect to a certain point on the straight line. And
Each of the pair of terminal processing units is connected to a terminal fixed to the housing corresponding to each of the pair of terminal processing units;
A thin acousto-electromechanical transducer characterized by An even number of the coils are formed,
Each of the even number of coils includes a first terminal unit and a second terminal unit as the pair of terminal processing units,
The relationship between the current flowing through each of the even coils and the mechanical force acting on each of the even coils is common between the even coils.
For each of the even number of coils, the first terminal portion is provided at one of the two locations, and the second terminal portion is provided at the other of the two locations,
The numbers of the first terminal unit and the second terminal unit are the same between the two locations,
The terminals are provided corresponding to all the first terminal portions and all the second terminal portions,
The thin acousto-electromechanical transducer according to claim 1. A speaker,
A thin acousto-electric transducer according to claim 1 or 2. The coil has a protruding portion protruding in a direction crossing its extending direction,
The thin acousto-electromechanical transducer according to claim 3. A communication path that communicates the space where the vibration film exists and the external space is provided,
The protrusion is provided in accordance with the communication path.
5. A thin acousto-electromechanical transducer according to claim 4.

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