JP2017022698A - Flat speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a sound quality and a sound pressure are decreased if a nonwoven fabric sheet is interposed between a diaphragm and a permanent magnet plate.SOLUTION: A flat speaker comprises a diaphragm on which a wiring pattern constituting a magnetic circuit is formed, a pair of permanent magnet plates opposed to each other across a diaphragm with a predetermined interval therebetween, and a casing that fixedly supports a pair of permanent magnet plates therein to restrict the movement of the diaphragm in the plate surface direction, and that supports the permanent magnets at positions separated from the respective permanent magnet plates in a plate thickness direction orthogonal to the plate surface direction. The diaphragm has a central region which vibrates in the plate thickness direction between a pair of permanent magnet plates by an electromagnetic force generated by a magnetic circuit and a peripheral region which surrounds the central region. Part of the peripheral region of the diaphragm is fixed to the casing and the peripheral region of the region fixed to the casing has lower rigidity than the central region, so that vibration in the plate thickness direction of the central region is permitted.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flat speaker that reproduces a sound source by vibrating a diaphragm.

  A flat speaker that reproduces a sound source by vibrating a flat diaphragm is known. The flat speaker generally has a structure in which a flat frame, a permanent magnet plate, a nonwoven fabric sheet, a flat diaphragm, a nonwoven fabric sheet, a permanent magnet plate, and a flat frame are sequentially stacked. The flat diaphragm is FPC (Flexible Printed Circuits) in which a predetermined pattern (voice coil) is printed and wired. When the voice coil is energized, it is opposed to the non-woven 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 vibration (that is, a reproduction sound obtained by reproducing a sound source) is radiated to the outside and is heard by a listener. For example, Patent Document 1 describes a specific configuration of this type of flat speaker.

  When the planar diaphragm vibrates in the thickness direction and mechanically interferes with the permanent magnet plate, the interference sound is emitted as noise (noise). The flat speaker described in Patent Document 1 is configured such that a nonwoven fabric sheet having a buffer function is interposed between the flat diaphragm and each permanent magnet plate, and the flat diaphragm does not directly interfere with the permanent magnet plate. This kind of noise is suppressed.

JP-A-9-331596

  However, if the nonwoven fabric sheet contains moisture or moisture, for example, the weight of the nonwoven fabric sheet becomes heavy and a load is applied to the planar diaphragm, or the volume of the nonwoven fabric sheet expands to increase the movable range of the planar diaphragm in the thickness direction. There is a risk that the sound quality and the sound pressure may be reduced due to a problem such as narrowing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress noise due to mechanical interference between the flat diaphragm and the permanent magnet plate even though the nonwoven fabric sheet is not provided. It is providing a suitable flat speaker.

  A flat speaker according to an embodiment of the present invention includes a diaphragm on which a wiring pattern constituting a magnetic circuit is formed, a pair of permanent magnet plates that are disposed opposite to each other with a predetermined interval between the diaphragm, A housing that fixes and supports a pair of permanent magnet plates inside and restricts the movement of the vibration plate in the plate surface direction, and supports the diaphragm at a position away from each permanent magnet plate in the plate thickness direction orthogonal to the plate surface direction; Is provided. The diaphragm has a central region that vibrates in the thickness direction between the pair of permanent magnet plates by an electromagnetic force generated by the magnetic circuit, and a peripheral region that surrounds the central region. A part of the peripheral area of the diaphragm is fixed to the casing, and the peripheral area of the area fixed to the casing is less rigid than the central area. Allow.

  In one embodiment of the present invention, a first slit may be formed in the peripheral area of the diaphragm around the area fixed to the housing.

  In one embodiment of the present invention, the diaphragm is screwed to the housing by a screw passed through a hole formed in the peripheral region, and a plurality of arc-shaped first electrodes that are substantially coaxial with the hole. The slit may be formed around the hole.

  In one embodiment of the present invention, the diaphragm may be fastened together with a flat speaker casing and a casing of a device mounting the flat speaker by screws.

  Further, in one embodiment of the present invention, the diaphragm has an outer peripheral side region of the peripheral region fixed to the casing over the entire periphery, and the plurality of first slits are all in the inner peripheral region of the peripheral region. It is good also as a structure formed side by side in the circumferential direction.

  In one embodiment of the present invention, in the peripheral region of the diaphragm, the region fixed to the housing and the first slit are formed at positions symmetrical with respect to a center line passing through the center of the diaphragm. Also good.

  In one embodiment of the present invention, the diaphragm may have a first reinforcing plate attached around the first slit.

  In one embodiment of the present invention, the housing includes a clearance in the thickness direction between one permanent magnet plate and the diaphragm, and a clearance in the thickness direction between the other permanent magnet plate and the diaphragm. It is good also as a structure which supports this diaphragm in the position where becomes equal.

  In one embodiment of the present invention, the diaphragm is housed in the housing, and is drawn out of the diaphragm main body including the central region and the diaphragm main body, and energizes the wiring pattern and the wiring pattern at the tip. It is good also as a structure which has the drawer part to which the connector which connects the circuit for this was attached. In this case, the diaphragm may have a shape in which the drawer portion and the central region are connected via a low-rigidity portion having lower rigidity than the drawer portion and the central region.

  In one embodiment of the present invention, the diaphragm may have a long second slit formed in the vicinity of the side of the diaphragm main body where the drawer portion is formed. In this case, for example, the low-rigidity portion has an elongated shape having a width defined by the side of the diaphragm main body and the side of the second slit arranged adjacent to the side.

  In one embodiment of the present invention, the low-rigidity part may have a shape that is symmetric with respect to a center line that passes through the center of the diaphragm.

  In one embodiment of the present invention, the diaphragm may have a configuration in which at least one rod-shaped second reinforcing plate is attached to the diaphragm main body. The rod shape has, for example, a shape that extends from near the side of the diaphragm main body to another side or near a vertex, or a shape that extends from near the top of the diaphragm main body to another vertex.

  In an embodiment of the present invention, the second reinforcing plate may have a symmetrical shape with a center line passing through the center of the diaphragm.

  Moreover, in one Embodiment of this invention, a 2nd reinforcement board is good also as what has a shape which combined the several rod shape arrange | positioned so that the center area | region may be enclosed near each edge | side of a diaphragm main body.

  Further, in one embodiment of the present invention, the diaphragm main body has a shape having a plurality of diagonal lines, and in this case, the second reinforcing plate has a plurality of bar shapes arranged respectively on the plurality of diagonal lines. It may have a combined shape.

  According to one embodiment of the present invention, there is provided a flat speaker that is suitable for suppressing noise due to mechanical interference between a flat diaphragm and a permanent magnet plate, even though the nonwoven fabric sheet is not provided.

It is an external appearance perspective view which shows the external appearance of the flat speaker which concerns on one Embodiment of this invention. It is a disassembled perspective view which shows the structure of the flat speaker which concerns on one Embodiment of this invention. It is a front view of the plane diaphragm with which the flat speaker concerning one embodiment of the present invention is equipped. It is sectional drawing which shows the fixation structure of the front cover and back plate with which the flat speaker which concerns on one Embodiment of this invention is equipped. It is a figure which shows the damper part formed in the general | schematic rectangular part of the plane diaphragm which concerns on the modification 1 of this invention. It is a figure which shows the structure around the damper part formed in the general | schematic rectangular part of the plane diaphragm which concerns on the modification 2 of this invention. It is a figure which shows the structure around the damper part formed in the general | schematic rectangular part of the plane diaphragm which concerns on the modification 3 of this invention. It is a figure which shows the structure around the damper part formed in the general | schematic rectangular part of the plane diaphragm which concerns on the modification 4 of this invention. It is a front view of the plane diaphragm with which the flat speaker which concerns on the modification 5 of this invention is equipped. It is a front view of the plane diaphragm with which the flat speaker which concerns on the modification 6 of this invention is equipped. It is a front view of the plane diaphragm with which the flat speaker which concerns on the modification 7 of this invention is equipped. It is a front view of the plane diaphragm with which the flat speaker which concerns on the modification 8 of this invention is equipped. It is a front view of the plane diaphragm with which the flat speaker which concerns on the modification 9 of this invention is equipped.

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

  FIG. 2 is an exploded perspective view showing the configuration of the flat speaker 1 according to the embodiment of the present invention. As shown in FIG. 2, the flat speaker 1 includes a planar diaphragm 10, a pair of permanent magnet plates 20 that are opposed to each other with a predetermined interval across the planar diaphragm 10, and a pair of permanent magnet plates 20. A metal casing (a front cover 30 and a back plate 40) that is housed and fixedly supported inside is provided.

  FIG. 3 is a front view of the planar diaphragm 10 according to the embodiment of the present invention. The planar diaphragm 10 is an FPC in which a copper foil pattern is formed on a base film, and has a substantially rectangular portion 10b and a lead portion 10c as shown in FIG. The base film (and coverlay) of the planar diaphragm 10 is formed of a flexible insulating resin film such as a polyethylene terephthalate film or an aromatic polyimide film.

  A meandering wiring pattern (voice coil 10a) constituting a magnetic circuit is formed in the central region of the substantially rectangular portion 10b. In addition, a plurality of damper portions 10g are formed side by side at a predetermined interval in the peripheral region of the substantially rectangular portion 10b surrounding the central region.

  The flat speaker 1 is configured to be driven by a multi-voice coil, that is, a plurality of voice coils in order to ensure sound pressure and achieve high-quality reproduction while being driven at a low voltage. Therefore, a plurality of voice coils (meandering copper foil patterns) 10 a are formed on the substantially rectangular portion 10 b of the planar diaphragm 10. In the drawing, for convenience, a plurality of voice coils 10a are shown as one pattern.

  The permanent magnet plate 20 has a substantially flat plate shape that is approximately the same size as the substantially rectangular portion 10b of the flat diaphragm 10, and is formed of, for example, a resin magnet or a rubber magnet containing ferrite or rare earth magnetic powder. In the permanent magnet plate 20, a parallel striped multipole magnetized pattern in which strip-shaped N poles and S poles appear alternately is formed over the entire surface of the planar diaphragm 10 facing the substantially rectangular portion 10 b. . In the multipolar magnetization patterns of the pair of permanent magnet plates 20, the N poles and the S poles face each other across the substantially rectangular portion 10 b of the planar diaphragm 10.

  In the multipolar magnetization pattern surface of the permanent magnet plate 20 on which the multipolar magnetization pattern is formed, the vicinity of each boundary between the N pole and the S pole is called a neutral zone, and adjacent to each other so as to straddle the neutral zone. A magnetic field from the matching N pole to the S pole is formed. That is, a magnetic field is formed along the surface of the substantially rectangular portion 10 b of the planar diaphragm 10.

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

  The planar diaphragm 10 is such that the straight line portion of the voice coil 10a (the straight line portion extending in the Y-axis direction in the figure) corresponds to the neutral zone of each permanent magnet plate 20 (specifically, the straight line of the voice coil 10a). The 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 high permeability metal part such as an iron plate, and has a substantially rectangular parallelepiped shape with one surface opened. A permanent magnet plate 20 is fixed to the inner surface of the front cover 30 by its own magnetic attractive force. The front cover 30 is also provided with similar sound wave emitting holes 30 a at positions corresponding to the sound wave emitting holes 20 a of the permanent magnet plate 20.

  The back plate 40 is also a high permeability metal part 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 side surface of the back plate 40 by its own magnetic attraction force. Similar sound wave emission holes 40 a are formed in the back plate 40 at positions corresponding to the sound wave emission holes 20 a of the permanent magnet plate 20.

  A plurality of screw holes 30b and flanges 30c are formed in the front cover 30. In the back plate 40, screw holes 40b are formed at positions corresponding to the respective screw holes 30b, and flanges 40c are formed at positions corresponding to the flanges 30c.

  FIG. 4 is a cross-sectional view showing a fixing structure between the front cover 30 and the back plate 40. As shown in FIG. 4, the screw 50 is passed through the screw hole 30 b of the front cover 30 and the screw hole 40 b of the back plate 40, and the nut 52 is tightened. By tightening the nut 52 at each location (six locations in the present embodiment), the front cover 30 and the back plate 40 are fixed, and a flat, substantially rectangular parallelepiped metal casing is completed. At this time, the flat diaphragm 10 is fastened together with a screw 50 through a hole 10gA formed in the damper portion 10g. Thereby, the movement of the general rectangular portion 10 b of the planar diaphragm 10 in the XY direction (the plate surface direction of the general rectangular portion 10 b) is restricted in the metal casing formed by the front cover 30 and the rear plate 40.

  As shown in FIG. 1, the drawer portion 10 c of the planar diaphragm 10 is drawn from the metal casing. A connector (not shown) is attached to the tip of the drawer 10c. The voice coil 10a has an input / output end connected to a connector via a lead pattern formed in the lead portion 10c, and is energized from an energization circuit connected to the connector.

  When the voice coil 10a is energized, the substantially rectangular portion 10b of the planar diaphragm 10 vibrates in the Z-axis direction between the pair of permanent magnet plates 20 by electromagnetic force in accordance with Fleming's left-hand rule. Sound waves generated by vibration (that is, reproduced sound obtained by reproducing a sound source) are radiated to the outside from the sound wave emission holes of the permanent magnet plate 20 and the front cover 30 and the sound wave emission holes of the permanent magnet plate 20 and the back plate 40. Listened to by the listener. The flat speaker 1 can reproduce a digital sound source with high sound quality because there is no deterioration in sound quality due to conventional analog conversion or the like.

  The screw hole 30b of the front cover 30 is formed at a position dropped to the back plate 40 side, and the screw hole 40b of the back plate 40 is formed at a position dropped to the front cover 30 side. Thereby, as shown in FIG. 4, the substantially rectangular portion 10 b of the planar diaphragm 10 has a clearance C <b> 1 in the Z-axis direction (the plate thickness direction of the approximately rectangular portion 10 b) with the permanent magnet plate 20 on the front cover 30 side. The Z-axis direction clearance C2 with the permanent magnet plate 20 on the back plate 40 side is supported at the same position.

  As described above, the substantially rectangular portion 10b of the planar diaphragm 10 is supported at a position away from each permanent magnet plate 20 in the Z-axis direction (specifically, a position where the clearance from each permanent magnet plate 20 is equal). ing. By ensuring clearance between each permanent magnet plate 20, mechanical interference to the permanent magnet plate 20 when the substantially rectangular portion 10b vibrates in the Z-axis direction is suppressed without interposing a nonwoven fabric sheet. Thus, noise (interference sound) is suppressed.

  Here, in FIG. 3, for convenience of explanation, the positions of the screw 50 and the nut 52 are indicated by a two-dot chain line. As can be seen from FIGS. 3 and 4, the peripheral area of the substantially rectangular portion 10 b of the planar diaphragm 10 is formed around the front cover 30 and the back plate around the holes 10 gA by screws 50 and nuts 52 passed through the holes 10 gA. By being sandwiched between 40 and 40, it is fixed to the metal casing.

  As shown in FIG. 3, the damper portion 10g is an area sandwiched between the front cover 30 and the back plate 40 (an area around the hole 10gA and is referred to as a “fixed area 10gB” for convenience of explanation. ) Is formed with a pair of arc-shaped slits 10gC that are substantially coaxial with the hole 10gA. Thereby, the rigidity of the substantially rectangular portion 10b of the planar diaphragm 10 is locally low around the fixed region 10gB.

  In the portion where the rigidity is low, the vibration of the substantially rectangular portion 10b (the central region where the voice coil 10a is printed and wired) when receiving electromagnetic force is gently absorbed. For this reason, the roughly rectangular portion 10b vibrates moderately when it receives an electromagnetic force, although it is fixed at a total of six locations in the peripheral region. Even if it is fixed at the six fixed regions 10gB, the vibration of the substantially rectangular portion 10b is not excessively suppressed, so that flat frequency characteristics with little distortion are obtained not only for high sounds but also for low sounds.

  The damper portion 10g is formed at a position that is symmetrical with respect to a center line (a chain line in FIG. 3) passing through the center of the substantially rectangular portion 10b of the planar diaphragm 10. By forming the damper portion 10g at a symmetrical position, twisting of the substantially rectangular portion 10b during vibration can be suppressed to a minimum. Since the twist of the substantially rectangular portion 10b is suppressed to a slight level, the position of the multipolar magnetization pattern of each permanent magnet plate 20 and the voice coil 10a in the XY plane can be maintained even when the roughly rectangular portion 10b vibrates. It becomes difficult to slip and the linearity of vibration is guaranteed.

  As shown in FIG. 3, GND lines 10d are formed on both sides of the drawing pattern of the voice coil 10a in the drawing portion 10c of the flat diaphragm 10a. The GND line 10d is not limited to both sides of the lead pattern as long as it is outside the region where the wiring pattern constituting the magnetic circuit is formed (in this embodiment, the region surrounded by the broken line in FIG. 3). You may form in another location.

  A small hole 10f is formed in the land 10e of the GND line 10d. The planar diaphragm 10 is fastened together with the flange 30c of the front cover 30 and the flange 40c of the back plate 40 by screws 60 passed through the small holes 10f. As a result, the voice coil 10 a is grounded to the metal casing formed by the front cover 30 and the back plate 40 via the GND line 10 d and the screw 60.

  When the voice coil 10a is grounded to a metal casing, the capacitance increases and the ground voltage is stabilized. Thereby, generation | occurrence | production of radiation noise is suppressed. Further, the flat diaphragm 10 is fastened together with the metal casing, whereby movement in the XY directions is more reliably regulated.

  The lead-out portion 10c has a width d1 over a substantially entire length extending from the tip to which the connector is attached to the vicinity of the boundary with the substantially rectangular portion 10b. The width d2 is narrower than the width d1. The lead pattern drawn out from each voice coil 10a is wired with a thickness sufficient to suppress a voltage drop due to impedance in a portion having the width d1, and is thinned in a portion having the width d2. ing.

  As described above, the drawer portion 10c is locally thinned between the boundary with the substantially rectangular portion 10b and the joint tightened portion by the screw 60 to reduce the rigidity of the drawer portion 10c, thereby receiving a plane that receives electromagnetic force. The substantially rectangular portion 10b of the diaphragm 10 can be vibrated with a small loss, and for example, a sound with less distortion can be reproduced.

  As shown in FIGS. 1 and 2, the back plate 40 is formed with a flange 40d. Screws (not shown) passed through the flange 40d are fastened to the housing of a device (electronic device such as a thin television or headphones) on which the flat speaker 1 is mounted, whereby the flat speaker 1 is attached to the device.

  The above is the description of the exemplary embodiments of the present invention. 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 embodiment of the present application also includes contents appropriately combined with examples and the like clearly shown in the specification or obvious examples.

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

[Modification 1]
FIG. 5 shows a damper portion 110g formed on the substantially rectangular portion 10b of the planar diaphragm 10 according to the first modification. As shown in FIG. 5, the damper portion 110g according to the first modification has a large number (more than a pair) of arc-shaped slits 110gC substantially coaxial with the hole 10gA around the fixed region 110gB. Thereby, around the fixed region 10gB, the vibration of the substantially rectangular portion 10b when receiving the electromagnetic force is more gently absorbed. Therefore, for example, it is advantageous for low-pitched sound reproduction.

[Modification 2]
FIG. 6 shows a configuration around the damper portion 10g formed in the substantially rectangular portion 10b of the flat diaphragm 10 according to the second modification. In the second modification, in order to reduce the weight of the substantially rectangular portion 10b and improve the sound quality and the sound pressure, the planar diaphragm 10 is formed using an FPC having a thin plate thickness. However, when the plate thickness of the approximately rectangular portion 10b is thin and light, the braking performance of the approximately rectangular portion 10b during vibration decreases. Therefore, in the second modification, as shown in FIG. 6, the reinforcing plate 10gD is attached to the periphery (the base film or the coverlay) of the damper portion 10g (the hole 10gA and the arc-shaped slit 10gC) by bonding or the like. Yes. Thereby, the fall of the braking performance of the substantially rectangular part 10b at the time of vibration is suppressed.

[Modification 3]
FIG. 7 shows a configuration around the damper portion 10g formed in the substantially rectangular portion 10b of the flat diaphragm 10 according to the third modification. In the third modification, the front cover 30 has eyelet holes 130b instead of the screw holes 30b, and the back plate 40 has eyelet portions 140b formed in an eyelet shape instead of the screw holes 40b. Have. The eyelet part 140b is inserted into the eyelet hole 130b as shown in FIG. 7A, and is pressed by an eyelet press machine (not shown) as shown in FIG. 7B. The front cover 30 and the back plate 40 are fixed by pressing the eyelet portion 140b at each location (for example, 6 locations as in the above embodiment), and a flat, substantially rectangular parallelepiped metal casing is formed. Complete. According to the third modification, the screw 50 is not necessary, and the number of parts is reduced.

[Modification 4]
FIG. 8 shows a configuration around the damper portion 10g formed in the substantially rectangular portion 10b of the planar diaphragm 10 according to the modification 4. In the fourth modification, the metal housing formed by the front cover 30 and the back plate 40 is a device (on which the rectangular portion 10b and the flat speaker 1 are mounted by a screw 70 passed through the eyelet hole 130b and the eyelet portion 140b ( It is fastened together with a housing 200 of an electronic device such as a thin television or headphones. According to the fourth modification, using the eyelet hole 130b and the eyelet part 140b as attachment holes for attaching to the housing 200 is advantageous in reducing the size of the electronic device on which the flat speaker 1 is mounted.

[Modification 5]
FIG. 9 is a front view of the planar diaphragm 10 according to the fifth modification. The planar diaphragm 10 according to the fifth modified example has a front cover 30 and a front cover 30 in a state where an outer peripheral side region (a hatched region in FIG. 9) is adhered to an elastic member such as rubber over the entire periphery. A plurality of slits 210gC are arranged in the entire circumferential direction in a region on the inner peripheral side of the peripheral region.

  As shown in FIG. 9, each pair of adjacent slits 210gC is formed such that the end of one slit 210gC is formed in a convex shape, and the end of the other slit 210gC facing this is formed in a concave shape. Yes. Thereby, the part which connects the area | region (hatching area | region in FIG. 9) of the outer periphery side of a peripheral area | region, and the center area | region where the voice coil 10a was printed wiring has comprised substantially C shape. In this case, it is possible to ensure the length of the portion having low rigidity as compared with the case where the portion connecting the outer peripheral side region of the peripheral region and the central region where the voice coil 10a is printed and wired is simply connected by a straight line. . Therefore, it becomes easy to appropriately set the vibration absorption performance due to the portion having low rigidity, and the configuration is suitable for appropriately vibrating the substantially rectangular portion 10b.

  As described above, the drawer portion 10c of the planar diaphragm 10 is fixed to the front cover 30 and the back plate 40 by screw tightening. Therefore, strictly speaking, the substantially rectangular portion 10b of the planar diaphragm 10 does not vibrate in a direction orthogonal to the surface of the permanent magnet plate 20 (Z-axis direction), and is around the small hole 10f of the lead-out portion 10c that is a screw tightening portion. As a fulcrum, it vibrates in a slightly inclined direction with respect to the Z-axis direction. When the inclination of the vibration direction of the roughly rectangular portion 10b with respect to the Z-axis direction is large, for example, noise due to mechanical interference between the planar diaphragm 10 and the permanent magnet plate 20 is generated or the roughly rectangular portion 10b vibrates and vibrates. This may cause noise. Therefore, it is desirable that the substantially rectangular portion 10b vibrates without being inclined with respect to the Z-axis direction. The planar diaphragm 10 according to the following modified examples 6 to 9 is preferably configured so that the substantially rectangular portion 10b vibrates without being inclined in the Z-axis direction.

[Modification 6]
FIG. 10 is a front view of the planar diaphragm 10 according to the sixth modification. As shown in FIG. 10, the flat diaphragm 10 according to the sixth modified example has a long elongated hole 10 h formed in the vicinity of the side of the substantially rectangular portion 10 b where the drawer portion 10 c is formed along the side. Yes. Since the elongated hole 10h is formed at this position, the planar diaphragm 10 has a central area of the substantially rectangular portion 10b (dotted line in FIG. 10) that mainly vibrates when energized to the drawer portion 10c and the voice coil 10a. In the sixth to ninth modifications, for convenience of description, the region is referred to as a “vibration region 10i”.) Is a pair of left and right defined mainly by the sides of the substantially rectangular portion 10b and the sides of the long hole 10h. It becomes the structure connected via the elongate shape 10j.

  In the planar diaphragm 10 according to the sixth modification, the cross-sectional area is small in the elongated shape 10j that connects the vibration region 10i and the lead portion 10c, and therefore the rigidity is locally low. Therefore, the vibration of the vibration region 10i when receiving the electromagnetic force is gently absorbed by the elongated shape 10j. In other words, since the elongated shape 10j bends during vibration of the vibration region 10i, the area around the small hole 10f of the lead-out portion 10c that is the screw tightening portion does not act as a fulcrum during vibration. Therefore, the inclination of the vibration direction of the vibration region 10i with respect to the Z-axis direction during vibration is suppressed. Since the suppression of noise is more advantageous as the inclination of the vibration direction of the vibration region 10i with respect to the Z-axis direction is suppressed, the planar diaphragm 10 according to the sixth modification has less distortion up to not only high sounds but also low sounds. It can be said that this configuration is suitable for obtaining a flat frequency characteristic.

  The elongated shape 10j has a symmetrical shape with a pair of left and right sides sandwiching a center line (a chain line in FIG. 10) passing through the center of the substantially rectangular portion 10b of the planar diaphragm 10. Since the pair of left and right elongated shapes 10j have a symmetrical shape, their rigidity is equal, and the vibration in the vibration region 10i is evenly absorbed by each elongated shape 10j. Therefore, for example, twisting of the vibration region 10i due to uneven absorption of vibration in the vibration region 10i in each elongated shape 10j is prevented.

  The narrower the elongated shape 10j is, the smaller the cross-sectional area is. Therefore, the elongated shape 10j is easily bent, and the vibration of the vibration region 10i is easily absorbed by the elongated shape 10j. Therefore, it is desirable that the elongated shape 10j is as thin as possible in consideration of durability.

  As the elongated shape 10j, which is a portion having low rigidity, is formed longer, the amount of bending of the elongated shape 10j during vibration increases, so that the vibration in the vibration region 10i is easily absorbed by the elongated shape 10j. For this reason, the elongated shape 10j is preferably as long as possible.

  As the width of the long hole 10h is wider, the outer diameter of the substantially rectangular portion 10b becomes larger. From the viewpoint of downsizing the flat speaker 1, it is desirable that the width of the long hole 10h is as narrow as possible. However, if the width of the long hole 10h is too narrow, the vibration region 10i and the elongated shape 10j may mechanically interfere with each other during vibration to generate noise. Therefore, the long hole 10h desirably has a minimum width that does not cause mechanical interference between the vibration region 10i and the elongated shape 10j during vibration.

[Modification 7]
FIG. 11 is a front view of the planar diaphragm 10 according to the seventh modification. The planar diaphragm 10 according to the seventh modification has the same configuration as the planar diaphragm 10 according to the sixth modification, except that the shape of the elongated hole 10h (and the elongated shape 10j associated therewith) is different.

  As shown in FIG. 11, in this modified example 7, the long hole 10h is formed in a U-shape along the three sides in the vicinity of the three sides including the side of the substantially rectangular portion 10b where the lead portion 10c is formed. Is formed. As a result, the pair of left and right elongated shapes 10j each have a substantially L shape, and the overall length thereof becomes longer. That is, according to the seventh modification example, the elongated shape 10j, which is a portion having low rigidity, is formed longer, and thus the vibration in the vibration region 10i is more easily absorbed by the elongated shape 10j.

[Modification 8]
FIG. 12 is a front view of the planar diaphragm 10 according to the modification 8. The planar diaphragm 10 according to the present modification 8 is for reducing the weight of the substantially rectangular portion 10b and improving the sound quality and sound pressure (particularly, for extending the high frequency characteristics more flat), for example, according to the modification 6. It is created using an FPC that is thinner than the flat diaphragm 10. However, since the rigidity of the substantially rectangular portion 10b is reduced by reducing the plate thickness, the braking performance of the vibration region 10i during vibration is reduced.

  Accordingly, as shown in FIG. 12, the planar diaphragm 10 according to the modification 8 has a reinforcing plate 10k (shown by hatching for the sake of convenience) attached to the peripheral area of the substantially rectangular portion 10b of the planar diaphragm 10 by bonding or the like. It is pasted. The planar diaphragm 10 according to the present modification 8 has the same configuration as the planar diaphragm 10 according to the present modification 6 except that the planar diaphragm 10 includes a thin plate and a reinforcing plate 10k.

  The reinforcing plate 10k has a shape surrounding the vibration region 10i. When the description is added, the reinforcing plate 10k has four rod shapes, and each rod-shaped end portion intersects (here, orthogonal) the adjacent rod-shaped end portion at each vertex of the substantially rectangular portion 10b. It has a shape. In this way, by attaching the reinforcing plate 10k to the substantially rectangular portion 10b, a decrease in rigidity of the approximately rectangular portion 10b due to a reduction in the plate thickness is suppressed over the entire vibration region 10i. Therefore, a reduction in braking performance of the vibration area 10i during vibration is suppressed.

  The four rods forming the reinforcing plate 10k are desirably integrated and have a uniform thickness so that a bent portion cannot be formed due to a difference in rigidity of the end portions.

  The reinforcing plate 10k is not attached to the elongated shape 10j in order to keep the rigidity of the elongated shape 10j low. Therefore, the vibration in the vibration region 10i is absorbed by the elongated shape 10j as in the sixth modification.

  Further, the reinforcing plate 10k has a symmetrical shape with a center line (a chain line in FIG. 12) passing through the center of the substantially rectangular portion 10b of the planar diaphragm 10 interposed therebetween. Since the reinforcing plate 10k has a symmetrical shape, a decrease in the rigidity of the substantially rectangular portion 10b due to a reduction in the plate thickness is uniformly suppressed over the entire vibration region 10i. This stabilizes the vibration of the vibration region 10i (for example, it does not vibrate due to undulations), which is advantageous for suppressing noise during vibration.

[Modification 9]
FIG. 13 is a front view of the planar diaphragm 10 according to the modification 9. Similarly to the eighth modification, the planar diaphragm 10 according to the ninth modification also reduces the weight of the substantially rectangular portion 10b to improve the sound quality and the sound pressure (particularly, in order to extend the high frequency characteristics more flatly). ), For example, using an FPC having a thickness smaller than that of the flat diaphragm 10 according to the modification 6. The planar diaphragm 10 according to Modification 9 has the same configuration as the planar diaphragm 10 according to Modification 8 except that the shape of the reinforcing plate 10k is different.

  As shown in FIG. 13, in the ninth modification, the reinforcing plate 10k has a substantially X-shaped reinforcing plate 10k (shown by hatching for convenience) attached on a pair of diagonal lines of the substantially rectangular portion 10b. It is attached. In other words, the reinforcing plate 10k according to the present modification 9 has a pair of rod shapes located on the diagonal lines of the substantially rectangular portion 10b. The pair of rod shapes intersect at the approximate center position of the substantially rectangular portion 10b.

  By sticking the reinforcing plate 10k having such a shape to the approximately rectangular portion 10b, a decrease in rigidity of the approximately rectangular portion 10b due to a reduction in the plate thickness is suppressed over the entire vibration region 10i. In the present modified example 9, since the region including the center position of the vibration region 10i is also reinforced by the reinforcing plate 10k, the decrease in the rigidity of the substantially rectangular portion 10b is further suitably suppressed. For this reason, a reduction in braking performance of the vibration region 10i during vibration is further suppressed.

  In addition, it is desirable that the pair of rods forming the reinforcing plate 10k are integrated and have a uniform thickness so that a bent portion cannot be formed due to a difference in rigidity at a portion intersecting in a substantially X shape.

  The reinforcing plate 10k according to the present modified example 8 has a shape combining four bar shapes extending from the vicinity of the side of the substantially rectangular portion 10b to the vicinity of another side, and the reinforcing plate 10k according to the modified example 9 is In addition, it has a shape obtained by combining two bar shapes extending from the vicinity of the vertex of the substantially rectangular portion 10b to the vicinity of another vertex. In another modification, the reinforcing plate 10k has a single bar shape extending from the vicinity of the side of the approximate rectangular portion 10b to the vicinity of another side or the vicinity of the apex, or 1 extending from the vicinity of the apex of the approximate rectangular portion 10b to the vicinity of the other apex. It may have a shape composed of a bar shape of a book. That is, by sticking the reinforcing plate 10k having at least one such bar shape to the roughly rectangular portion 10b, a decrease in rigidity of the roughly rectangular portion 10b due to a reduction in the plate thickness is suppressed, and vibration during vibration is generated. A decrease in braking performance in the region 10i is suppressed.

DESCRIPTION OF SYMBOLS 1 Flat speaker 10 Plane diaphragm 10a Voice coil 10b Outline rectangular part 10c Drawer part 10d GND line 10e Land 10f Small hole 10g Damper part 10gA Hole 10gB Fixing area 10gC Arc-shaped slit 10gD Reinforcement board 10h Slot 10i Vibration area 10j Slender shape 10k Reinforcing plate 20 Permanent magnet plate 20a Sound wave emitting hole 30 Front cover 30a Sound wave emitting hole 30b Screw hole 30c Flange 40 Back plate 40a Sound wave emitting hole 40b Screw hole 40c, 40d Flange 50, 60, 70 Screw 52 Nut 130b Eyelet hole 140b Eyelet Part

Claims (15)

A diaphragm on which a wiring pattern constituting a magnetic circuit is formed;
A pair of permanent magnet plates sandwiched between the diaphragms and arranged to face each other at a predetermined interval;
The pair of permanent magnet plates are fixedly supported therein, and the diaphragm is restricted from moving in the plate surface direction and supported at a position away from each permanent magnet plate in the plate thickness direction orthogonal to the plate surface direction. A housing,
With
The diaphragm is
A central region that vibrates in the plate thickness direction between the pair of permanent magnet plates by electromagnetic force generated in the magnetic circuit;
A peripheral region surrounding the central region;
Have
The peripheral region is
A part is fixed to the housing,
Peripheral region of the region fixed to the housing is less rigid than the central region, thereby allowing vibration in the thickness direction of the central region,
Flat speaker. A first slit is formed around the area fixed to the housing,
The flat speaker according to claim 1. The diaphragm is
It is screwed to the housing by screws passed through holes formed in the peripheral area,
A plurality of arc-shaped first slits that are substantially coaxial with the hole are formed around the hole,
The flat speaker according to claim 2. The diaphragm is
The screws are fastened together with the housing of the flat speaker and the housing of the device mounting the flat speaker.
The flat speaker according to claim 3. The diaphragm is
A region on the outer peripheral side of the peripheral region is fixed to the housing over the entire periphery,
In the region on the inner peripheral side of the peripheral region, a plurality of first slits are formed side by side in the entire circumferential direction.
The flat speaker according to claim 2. The region fixed to the housing and the first slit are:
It is formed in a symmetrical position across a center line passing through the center of the diaphragm,
The flat speaker as described in any one of Claims 2-5. The diaphragm is
A first reinforcing plate is attached around the first slit,
The flat speaker as described in any one of Claims 2-6. The housing is
The diaphragm is supported at a position where the clearance in the plate thickness direction between the one permanent magnet plate and the diaphragm and the clearance in the plate thickness direction between the other permanent magnet plate and the diaphragm are equal. ,
The flat speaker as described in any one of Claims 1-7. The diaphragm is
A diaphragm main body housed in the housing and including the central region;
A lead-out part that is pulled out from the diaphragm main body and has a connector attached to the tip to connect the wiring pattern and a circuit for energizing the wiring pattern;
Have
The drawer portion and the central region have a shape connected via the drawer portion and a low-rigidity portion that is less rigid than the central region,
The flat speaker as described in any one of Claims 1-8. The diaphragm is
A long second slit is formed in the vicinity of the side of the diaphragm main body where the drawer portion is formed, along the side.
The low rigidity portion is
Having an elongated shape having a width defined by the side of the diaphragm main body and the side of the second slit arranged adjacent to the side;
The flat speaker according to claim 9. The low rigidity portion is
Having a symmetrical shape across a center line passing through the center of the diaphragm,
The flat speaker according to claim 9 or 10. The diaphragm is
A second reinforcing plate having at least one bar shape is attached to the diaphragm main body,
The bar shape is
Having a shape extending from near the side of the diaphragm main body to another side or near a vertex, or extending from near the top of the diaphragm main body to another vertex.
The flat speaker as described in any one of Claims 1-11. The second reinforcing plate is
Having a symmetrical shape across a center line passing through the center of the diaphragm,
The flat speaker according to claim 12. The second reinforcing plate is
Having a shape combining a plurality of the rod shapes arranged so as to surround the central region near each side of the diaphragm main body,
A flat speaker according to claim 12 or claim 13. The diaphragm main body has a shape having a plurality of diagonal lines,
The second reinforcing plate is
It has a shape combining a plurality of the rod shapes arranged on each of the plurality of diagonal lines,
A flat speaker according to claim 12 or claim 13.

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