Sound generating device

Abstract

To provide a sounding device capable of stably holding a curved vibrating sheet edge in a vibrating state.SOLUTION: In a sounding device 1, a flexible vibration sheet 10 such as an FPC is supported on a base portion 2. A pair of edge support portions 20a and 20b are fixed to the base portion 2. The edge support portions 20a and 20b have an outer support yoke 21, an inner support yoke 22, and a magnet 23. A support gap SG is formed between the outer support yoke 21 and the inner support yoke 22. The inside of the support gap SG is filled with a fluid or a powder magnetic material layer. The left edge portion 15 and the right edge portion 16 of the vibration sheet 10 are supported in the support gap SG. A coil layer 18 is provided on the vibration sheet 10, and a magnetic field is applied to the coil layer 18 from a magnetic field generating portion 31.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sound generating device that generates sound pressure by vibrating a flexible vibrating sheet. [Background technology]

[0002] Patent Document 1 describes an invention related to a universal speaker. This universal speaker has a curved diaphragm. Paragraph

[0040] states that the material of the curved diaphragm can be paper such as carbon paper, flexible plastic such as polyimide or polyester, wood such as balsa wood, or metal such as aluminum, beryllium, or boron.

[0003] The curved diaphragm is provided so as to cover the opening of the housing, and the upper end of the curved diaphragm is fixed to the housing. A driver is fixed to the housing. The driver is a moving magnet type, and a clamping tool having spring elasticity is fixed to a pole piece on which a magnet is provided. The lower end of the curved diaphragm is clamped by the clamping tool, and the curved diaphragm and the pole piece are connected. When the pole piece of the driver is driven, vibration is applied to the curved diaphragm via the clamping tool.

[0004] As shown in Figure 8, the universal speaker has curved guide protrusions fixed to the opposing surfaces of a pair of side panels provided on the housing, and the inner surfaces of both sides of the curved diaphragm are supported by the respective guide protrusions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5668233 Summary of the Invention [Problem to be solved by the invention]

[0006] In the universal speaker described in Patent Document 1, both curved sides of the curved diaphragm made of paper or plastic are simply supported from the inside by guide protrusions, and are not firmly bound. Therefore, when vibrations are applied to the curved diaphragm from the driver, irregular wrinkles and twists tend to occur in the curved diaphragm, which can easily cause a decrease in sensitivity when sound is produced and the generation of noise.

[0007] In addition, since the gaps between the edges of both sides of the curved diaphragm and the housing are not completely sealed, the sound pressure emitted forward from the front of the curved diaphragm and the out-of-phase sound pressure emitted from the back of the curved diaphragm toward the inside of the housing are likely to interfere with each other through the gaps, which can lead to a decrease in the ability to reproduce low-frequency sounds.

[0008] The present invention is devised to solve the above-mentioned problems of the conventional art, and aims to provide a sound-producing device that can support the edge of a vibrating sheet so that it can vibrate with a light load, and can improve the vibration characteristics of the vibrating sheet.

[0009] Another object of the present invention is to provide a sound-generating device that can seal the gap between the edge of the vibrating sheet and the base, thereby suppressing interference between the sound pressure applied from the surface of the vibrating sheet and the sound pressure generated at the rear surface. [Means for solving the problem]

[0010] The present invention provides a sound generating device including a flexible vibrating sheet, a base portion supporting the vibrating sheet, and a drive mechanism for applying a vibration force to the vibrating sheet, the vibrating sheet has a fixed end and a driving end located at both ends in a vertical direction, and left and right edges extending in the vertical direction, the fixed end being fixed to the base portion, The base portion is provided with edge support portions that support at least a part of the left and right edges of the vibrating sheet so that the vibrating sheet can vibrate. the edge support comprises a support yoke made of a magnetic material forming a support gap in which the edge intervenes, a layer of magnetic material in a fluid or powder form located in the support gap between the support yoke and the edge, and a magnet for applying a magnetic field across the support gap to the support yoke, The support gap is curved in the vertical direction, and the vibrating sheet is curved in the vertical direction, that Each The above Within the support gap The edge portion is supported by the magnetic material layer on both sides of the edge portion. It has been The present invention is characterized in that a longitudinal vibration is applied to the driving side end portion from the driving mechanism, causing the edge portion of the vibrating sheet to vibrate within the support gap in a direction intersecting the transverse direction of the magnetic field.

[0011] The sound-producing device of the present invention is the vibrating sheet Vibration direction but, The direction intersects with the bridge aggregation direction of the magnetic powder contained in the magnetic material layer within the support gap.

[0012] In the sound producing device of the present invention, it is preferable that both edge portions of the vibrating sheet are supported by the edge support portions over substantially the entire length of the intermediate vibrating portion excluding the fixed side end and the driving side end of the vibrating sheet.

[0013] Furthermore, it is preferable that gaps between both edges of the vibrating sheet and the base portion are filled by the edge support portions. Effect of the Invention

[0014] In the sound-producing device of the present invention, a magnetic field is applied to a fluid or powdery magnetic material layer in the support gap of the edge support portion, and the edge of the vibrating sheet is held by the magnetic material layer in the support gap. The vibrating sheet is held in the edge support portion so that it can vibrate with relatively low friction while maintaining its shape. In particular, when the curved portion of the vibrating sheet is held by the magnetic material layer, the vibrating sheet can vibrate while maintaining its curved shape. Therefore, when vibration is applied to the vibrating sheet along its surface, it is possible to prevent the occurrence of irregular deformation such as wrinkles or twists in the vibrating sheet, and it is possible to increase the sound-producing sensitivity and suppress the generation of noise.

[0015] Furthermore, by designing the gap between the edge of the vibrating sheet and the base portion to be sealed with an edge support portion, interference between the sound pressure generated on the surface of the vibrating sheet and the sound pressure generated on the back side of the base portion can be prevented, thereby improving acoustic performance, such as increasing sound pressure in the low-frequency range. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a front perspective view of the sound generating device according to the embodiment of the present invention; [Diagram 2] FIG. 2 is an exploded perspective view of the sound generating device shown in FIG. 1, seen from the front; [Diagram 3] FIG. 2 is an enlarged exploded perspective view of part III of the sound generating device shown in FIG. [Figure 4] FIG. 2 is a longitudinal sectional view of the sound generating device shown in FIG. [Diagram 5] 2 is a cross-sectional view of the sound generating device shown in FIG. 1 taken along line VV; [Figure 6] FIG. 1 is a longitudinal sectional view showing an assembly example of a sound generating device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1 to 5, the Z1-Z2 direction is the front-rear direction, the Z1 direction is the front, the Z2 direction is the rear and toward the inside of the base, the Y1-Y2 direction is the up-down direction, the Y1 direction is the up and the Y2 direction is the down, the X1-X2 direction is the left-right direction, the X1 direction is the left direction and the X2 direction is the right direction. In the sound generation device 1, sound pressure is mainly generated in the forward direction (Z1 direction), but sound pressure is also applied diagonally upward.

[0018] As shown in Figs. 1 and 2, the sound generation device 1 has a base portion 2. The base portion 2 is a support housing or a support base. The base portion 2 has a bottom wall portion 3 located on the lower side (Y2 side) and parallel to the XZ plane, and a rear wall portion 4 located on the rear side (Z2 side) and parallel to the XY plane. The bottom wall portion 3 and the rear wall portion 4 are formed integrally. The base portion 2 is provided with a left side wall portion 5 and a right side wall portion 6 that face each other in the left-right direction (X1-X2 direction). The left side wall portion 5 and the right side wall portion 6 are formed separately from the bottom wall portion 3 and the rear wall portion 4, and are incorporated into and fixed to the bottom wall portion 3 and the rear wall portion 4.

[0019] At least the left side wall 5 and the right side wall 6 of the base 2 are made of a non-magnetic material. The left side wall 5 has an opposing inner surface 5a facing the inside of the base 2, and the right side wall 6 also has an opposing inner surface 6a facing the inside of the base 2. As shown in FIG. 2, a holding recess 6b is formed along the front edge of the opposing inner surface 6a of the right side wall 6. The holding recess 6b is formed along a curved locus having a curvature in the up-down direction. A holding recess 5b is also formed on the opposing inner surface 5a of the left side wall 5 in a similar manner. FIG. 5 shows the cross-sectional shape of the holding recess 5b of the left side wall 5. The holding recess 5b and the holding recess 6b are plane-symmetrical in the left-right direction (X1-X2 direction).

[0020] 2 and 4, a support rib 7 that protrudes forward (in the Z1 direction) is integrally formed on the upper part of the rear wall 4 of the base 2, and the upper surface of the support rib 7 serves as an end fixing part 7a. The front end of the bottom wall 3 serves as a thick part 8, and the end surface of the thick part 8 facing forward (in the Z1 direction) serves as a drive mechanism fixing part 8a.

[0021] As shown in FIG. 1, between the left side wall 5 and the right side wall 6 of the base 2, a vibrating sheet 10 is provided from the end fixing portion 7a to the drive mechanism fixing portion 8a. The V1-V2 direction is the vertical direction of the vibrating sheet 10. The length dimension of the vibrating sheet 10 in the vertical direction (V1-V2 direction) is longer than the width dimension in the left-right direction (X1-X2 direction) perpendicular to the vertical direction. However, the length dimension of the vibrating sheet 10 in the vertical direction may be shorter than the width dimension in the left-right direction. The vertical direction (V1-V2 direction) of the vibrating sheet 10 is the vibration direction and the direction in which vibration is transmitted.

[0022] 2, the vibrating sheet 10 has a fixed end 11 at its upper end in the vertical direction (V1 direction) and a driving end 12 at its lower end in the vertical direction (V2 direction). The vibrating sheet 10 has an intermediate vibrating section 13 between the fixed end 11 and the fixed end 12. The vibrating sheet 10 is rectangular, and has a left edge 15 and a right edge 16 that extend parallel to each other in the vertical direction (V1-V2 direction). The vibrating sheet 10 also has a front surface 10a facing forward (Z1 direction) and a back surface 10b facing backward (Z2 direction), i.e., toward the inside of the base section 2.

[0023] The vibrating sheet 10 is a flexible sheet having elasticity, and is basically composed of a resin sheet formed of a synthetic resin material. The vibrating sheet 10 is preferably composed of a so-called flexible circuit board (FPC) in which a copper foil layer is laminated as a metal film on the surface of a resin sheet (base film) formed of a polyimide resin or a PET resin. The vibrating sheet 10 is preferably provided with a copper foil layer on almost the entire area of ​​the intermediate vibration part 13 except for the fixed side end 11 and the driving side end 12, or is preferably provided with a copper foil layer on the entire area except for the driving side end 12. Alternatively, the vibrating sheet 10 is preferably provided with a copper foil layer on at least the entire curved area. By forming the flexible sheet constituting the vibrating sheet 10 from an FPC, the vibrating sheet 10 can be formed thin while having high rigidity and elasticity, and it becomes easier to prevent unnecessary deformation during vibration.

[0024] As shown in FIG. 1 and FIG. 5, the left edge support part 20a is held and fixed in the holding recess 5b of the left side wall part 5 of the base part 2, and as shown in FIG. 1, the right edge support part 20b is held and fixed in the holding recess 6b of the right side wall part 6. The edge support parts 20a and 20b have a plane-symmetrical structure in the left-right direction (X1-X2 direction). As shown in FIG. 5, the left edge support part 20a has an outer support yoke 21 facing the outside of the base part 2 and an inner support yoke 22 facing the inside of the base part 2. The outer support yoke 21 and the inner support yoke 22 are formed of a magnetic material mainly made of iron. On the left side (X1 side), a magnet (permanent magnet) 23 is sandwiched between the outer support yoke 21 and the inner support yoke 22. The magnet 23 has an outer surface 23a that is surface-joined with the outer support yoke 21 and an inner surface 23b that is surface-joined with the inner support yoke 22, and the outer surface 23a and the inner surface 23b are magnetized so as to have opposite magnetic properties.

[0025] As shown in Fig. 5, on the right side (X2 side) of the edge support portion 20a, the end face 21a of the outer support yoke 21 and the end face 22a of the inner support yoke 22 face each other. The end faces 21a and 22a are curved surfaces that are curved with a curvature in the vertical direction (V1-V2 direction), and the end faces 21a and 22a face each other with a short distance δ between them. The opposing space between the end faces 21a and 22a is the support gap SG. The magnetic flux of the magnet 23 travels from the outer support yoke 21 across the support gap SG and circulates around the inner support yoke 22.

[0026] The right edge support part 20b shown in Fig. 2 is plane symmetrical to the left edge support part 20a. The right edge support part 20b also has an outer support yoke 21, an inner support yoke 22, and a magnet 23, and a support gap SG is formed at the opposing portion between the outer support yoke 21 and the inner support yoke 22.

[0027] As shown in FIG. 2, the left edge support portion 20a and the right edge support portion 20b are divided into a curved support portion 25 and a fixed support portion 26 above the curved support portion 25. The curved support portion 25 has a curvature in the vertical direction (V1-V2 direction) and is curved so that the protruding direction faces forward (Z1 direction). The fixed support portion 26 extends in the front-rear direction (Z1-Z2 direction). In the edge support portion 20a and the edge support portion 20b, a support gap SG is provided over the entire length of the curved support portion 25 and the fixed support portion 26. The magnet 23 is also provided over the entire length of the curved support portion 25 and the fixed support portion 26. However, the magnet 23 may be provided only in a part of the curved support portion 25 in the vertical direction (V1-V2 direction). Even if the magnet 23 is provided only in a part, it is possible to make the magnetic flux cross the support gap SG over the entire length in the vertical direction.

[0028] In the edge support portion 20a and the edge support portion 20b, a magnetic material layer is provided inside the support gap SG over the entire vertical length. The magnetic material layer is in a fluid or powder form. The fluid magnetic material layer is a magnetorheological fluid (MR fluid). The magnetorheological fluid is a slurry containing magnetic powder in a fluid, and a fluorine-based oil or the like is used as the fluid, and a ferromagnetic powder such as magnetite is used as the magnetic powder. As the powder magnetic material layer, a ferromagnetic powder such as magnetite that has been surface-treated with a surfactant can be used without oil. Alternatively, the ferromagnetic powder treated with a surfactant may be mixed with a small amount of oil.

[0029] In edge support portions 20a and 20b, magnetic flux crosses within the support gap SG from the outer support yoke 21 to the inner support yoke 22, so that the ferromagnetic powder in the support gap SG agglomerates in a bridge shape in the direction crossing the support gap SG.

[0030] 1, a drive mechanism 30 is provided at the lower front part of the sound generation device 1. The drive mechanism 30 is composed of a coil layer 18 provided at the drive side end part 12 of the vibrating sheet 10, and a magnetic field generating part 31 fixed to the drive mechanism fixing part 8a of the base part 2.

[0031] As shown in FIG. 2, the coil layer 18 has a planar winding shape in which the conductor layer winds around the sheet surface of the vibrating sheet 10 at the driving side end 12. The planar winding coil layer 18 is wound in multiple layers so as to wind around a virtual center line perpendicular to the sheet surface of the driving side end 12. The coil layer 18 has an upper current-carrying portion 18a extending in the left-right direction at the top and a lower current-carrying portion 18b extending in the left-right direction at the bottom. Voice currents flow in opposite directions in the left-right direction in the upper current-carrying portion 18a and the lower current-carrying portion 18b. The coil layer 18 is provided on both the front surface 10a and the back surface 10b of the vibrating sheet 10, and the coil layers 18 on the front and back surfaces are connected in series via a conductive layer that penetrates the vibrating sheet 10 in the plate thickness direction. In addition, a terminal portion that is conductive to one end of the conductor layer constituting the coil layer 18 and a terminal portion that is conductive to the other end of the conductor layer are provided on the front surface 10a or the back surface 10b of the vibrating sheet 10.

[0032] The conductor layer and terminal portion constituting the coil layer 18 are formed by etching the copper foil layer of the vibrating sheet 10 made of an FPC and leaving a part of the copper foil layer. Alternatively, a thin conductor wire may be wound in a plane in advance to form a planar wound coil structure, and the coil layer 18 may be bonded to the sheet surface of the vibrating sheet 10 at the driving side end portion 12. The coil layer 18 may be provided only on the back surface 10b facing the rear (Z2 direction) of the vibrating sheet 10, or may be provided only on the front surface 10a facing the front (Z1 direction).

[0033] As shown in FIG. 2, FIG. 3, and FIG. 4, the magnetic field generating unit 31 has an opposing yoke 32 made of a magnetic material. The opposing yoke 32 is fixed to the drive mechanism fixing portion 8a, which is the tip surface of the bottom wall portion 3 of the base portion 2. A magnet assembly 36 is provided in front of the opposing yoke 32. The magnet assembly 36 is composed of a lower yoke 33 made of a magnetic material, a magnet 34 stacked thereon, and an upper yoke 35 made of a magnetic material and located thereon. A pair of spacers 37 are interposed on both the left and right sides of the magnet assembly 36. The spacers 37 are made of a non-magnetic material, and the left and right spacers 37 are integrally formed with thin plate portions 37a extending in directions opposite to each other. On both the left and right sides of the magnet assembly 36, the thin plate portions 37a are interposed between the opposing yoke 32 and the magnet assembly 36.

[0034] 1, in the magnetic field generating unit 31, the thin plate portions 37a of the left and right spacers 37 are positioned in front of the opposing yoke 32 fixed to the drive mechanism fixing unit 8a, and the magnet assembly 36 is attached in front of them. The opposing yoke 32 and the magnet assembly 36 are brought into close contact with each other by the force of the magnetic field generated by the magnet 34, with the thin plate portions 37a of the spacers 37 sandwiched between them. In addition, by interposing the thin plate portions 37a of the spacers 37 between the opposing yoke 32 and the magnet assembly 36, a minute drive gap DG shown in FIGS. 3 and 4 is formed between the opposing yoke 32 and the magnet assembly 36.

[0035] 3, the lower end of the curved support portion 25 of the left edge support portion 20a extends to a position where it contacts the upper end of the opposing yoke 32 and the upper end of the magnet assembly 36. Similarly, the lower end of the curved support portion 25 of the right edge support portion 20b extends to a position where it contacts the upper end of the opposing yoke 32 and the upper end of the magnet assembly 36.

[0036] 1 and 4, a vibrating sheet 10 is installed between a left side wall 5 and a right side wall 6 of a base (support housing) 2, and the front (Z1 direction) and diagonally upward of the base 2 are blocked by the vibrating sheet 10. As shown in Fig. 5, at the curved support portion 25 and the fixed support portion 26 of the left edge support portion 20a, a left edge portion 15 of the vibrating sheet 10 is inserted into the support gap SG, and as shown in Fig. 1, at the curved support portion 25 and the fixed support portion 26 of the right edge support portion 20b, a right edge portion 16 of the vibrating sheet 10 is also inserted into the support gap SG.

[0037] As shown in FIG. 5, in the support gap SG, a magnetic material layer is filled between the sheet surface 10a of the left edge portion 15 of the vibrating sheet 10 and the end face 21a of the outer support yoke 21, and a magnetic material layer is filled between the sheet back surface 10b and the end face 22a of the inner support yoke 22. Due to the magnetic field of the magnet 23, ferromagnetic powder is aggregated in a bridge shape between the sheet surface 10a and the end face 21a, and ferromagnetic powder is aggregated in a bridge shape between the sheet back surface 10b and the end face 22a. In the support gap SG, the surface and back surface of the left edge portion 15 of the vibrating sheet 11 are held by the magnetic material layer. Similarly, in the right edge portion 16 of the vibrating sheet 10, the sheet surface 10a and the sheet back surface 10b are held by a bridge-shaped aggregation of ferromagnetic powder in the support gap SG of the right edge support portion 20b.

[0038] Due to the bridge-shaped aggregation of the magnetic material layer in the support gap SG, the vibrating sheet 10 is stably held with its intermediate vibrating portion 13 maintaining a curved state with a curvature in the vertical direction (V1-V2 direction). At the upper end of the vibrating sheet 10, a fixed end portion 11 is bent backward (Z2 direction). With both edges 15, 16 of the vibrating sheet 10 held in the support gap SG, the fixed end portion 11 is adhered and fixed to the end fixing portion 7a, which is the upper surface of the support rib 7 of the base portion 2.

[0039] 3 and 4, the driving side end 12 at the lower end of the vibrating sheet 10 is inserted into the driving gap DG of the magnetic field generating unit 31. The coil layer 18 provided at the driving side end 12 has an upper current-carrying part 18a located in the gap where the opposing yoke 32 and the upper yoke 35 face each other, and a lower current-carrying part 18b located in the gap where the opposing yoke 32 and the lower yoke 33 face each other. In the driving gap DG, it is preferable that a thin elastic sheet, grease, magnetorheological fluid, or the like is interposed between the opposing yoke 32 and the driving side end 12 and between the magnet assembly 36 and the driving side end 12 to prevent the coil layer 18 and the magnetic field generating unit 31 from directly rubbing against each other.

[0040] Next, the sound production operation of the sound production device 1 will be described. When a voice current is applied to the coil layers 18 provided on both the front and back sides of the driving side end 12 of the vibrating sheet 10, the electromagnetic forces generated by the currents flowing in opposite directions in the upper and lower current conducting portions 18a and 18b and the magnetic fluxes crossing the upper and lower current conducting portions 18a and 18b in opposite directions within the driving gap DG cause the vibrating sheet 10 to vibrate in a vertical direction (V1-V2 direction) along the sheet surface.

[0041] When a vibration force in the vertical direction (V1-V2 direction) is applied to the vibrating sheet 10, the vibrating sheet 10 moves slightly in the vertical direction, and depending on the vibration frequency, a regular wave-like deformation occurs, and sound pressure is applied to the space in front of the vibrating sheet 10 (Z1 direction) and diagonally above it. The left edge 15 and the right edge 16 of the vibrating sheet 10 are supported by magnetic material layers from both sides within the support gap SG of the edge support parts 20a and 20b, so that the intermediate vibrating part 13 of the vibrating sheet 10 can vibrate in a stable state while maintaining its curved shape. Therefore, it is possible to prevent the intermediate vibrating part 13 from being deformed by unexpected irregular wrinkles or twists, and to suppress the generation of noise during sound generation. Note that the vibration direction of the vibrating sheet 10 within the support gap SG is a direction that intersects with the aggregation direction of the bridge of the ferromagnetic powder, so that the frictional resistance when the vibrating sheet 10 vibrates in the vertical direction (V1-V2 direction) does not become excessive.

[0042] In addition, the gap between the left edge 15 of the vibrating sheet 10 and the left side wall 5 is closed by the edge support part 20a over the entire length in the vertical direction (V1-V2 direction), and the gap between the right edge 16 and the right side wall 6 is covered by the edge support part 20b. Therefore, the sound pressure applied forward (Z1 direction) and diagonally upward from the front surface 10a of the vibrating sheet 11 by the vibration of the vibrating sheet 10 and the phase-inverted sound pressure applied inward from the back surface 10b of the vibrating sheet 10 to the base part 2 are less likely to interfere with each other, and the reproduction ability of the low-frequency range can be improved.

[0043] In the sound generating device 1 of the embodiment, the edges 15, 16 are supported in the support gaps SD of the edge support parts 20a, 20b over almost the entire length of the vibrating sheet 10 in the vertical direction, and the edges 15, 16 are held in the support gaps SD over the entire length of the intermediate vibrating part 13. However, in the present invention, at least one edge of the vibrating sheet 10 and at least a part of the edge in the vertical direction may be held in the support gaps SG of the edge support parts. However, it is preferable that the curved part of the vibrating sheet 10 having at least a curvature in the vertical direction is held in the support gap SG along the curved part. By holding the edge along the curved part by the magnetic material layer, the curved shape of the vibrating sheet 10 can be maintained during vibration, and irregular wrinkles and twists can be prevented from occurring in the curved part.

[0044] FIG. 6 shows an assembly example in which two sound generation devices 1 according to the embodiment are combined together. In this assembly example, a pair of sound generation devices 1 are connected in a facing position. In the left and right sound generation devices 1, one magnet assembly 36 is commonly used for the magnetic field generating section 31 constituting the drive mechanism 30. The opposing yokes 32 of the sound generation devices 1 face each other on both sides in the left-right direction (X1-X2 direction) of the magnet assembly 36, and two drive gaps DG are formed. The base section 2 and the vibrating sheet 10 are provided as a pair facing each other, and the drive side end 12 of each vibrating sheet 10 is interposed within the respective drive gaps DG. [Explanation of symbols]

[0045] 1. Sound generating device 2 Base 5 Left side wall 6 Right side wall 10 Vibrating Sheet 11 Fixed side end 12 Drive end 13 Intermediate vibration section 15 Left edge 16 Right edge 18 Coil Layer 20a, 20b Edge support part 21 Outer support yoke 22 Inner support yoke 23 Magnet 30 Drive mechanism 31 Magnetic field generating unit DG driving gap SG Support Gap

Claims

1. A sound generating device including a flexible vibrating sheet, a base portion supporting the vibrating sheet, and a drive mechanism for applying a vibration force to the vibrating sheet, the vibrating sheet has a fixed end and a driving end located at both ends in a vertical direction, and left and right edges extending in the vertical direction, the fixed end being fixed to the base portion, The base portion is provided with edge support portions that support at least a part of the left and right edges of the vibrating sheet so that the vibrating sheet can vibrate. the edge support comprises a support yoke made of a magnetic material forming a support gap in which the edge intervenes, a layer of magnetic material in a fluid or powder form located in the support gap between the support yoke and the edge, and a magnet for applying a magnetic field across the support gap to the support yoke, The support gap is curved in a vertical direction, the vibrating sheet is curved in a vertical direction, and within each of the support gaps, the edge portion is held by the magnetic material layer from the front and rear surfaces thereof, A sound-producing device characterized in that a longitudinal vibration is applied to the driving side end from the driving mechanism, causing the edge of the vibrating sheet to vibrate within the support gap in a direction intersecting the transverse direction of the magnetic field.

2. 2. The sound generating device according to claim 1, wherein the vibration direction of the vibrating sheet is a direction intersecting a bridge aggregation direction of the magnetic powder contained in the magnetic material layer within the support gap.

3. 3. The sound generating device according to claim 1, wherein both edge portions of said vibrating sheet are supported by said edge support portions over substantially the entire length of said intermediate vibrating portion excluding said fixed side end portion and said driving side end portion of said vibrating sheet.

4. 4. The sound generating device according to claim 1, wherein gaps between both edges of the vibrating sheet and the base are filled with the edge support parts.

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