JP7650131B2 - Sound generating device - Google Patents

Description

The present invention relates to a sound generating device that generates sound pressure by vibrating a curved vibrating sheet.

Patent Document 1 describes an invention relating to a universal speaker.
This universal speaker has a curved diaphragm. Paragraph [0040] of Patent Document 1 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.

The curved diaphragm is arranged to cover the opening of the housing, and one end 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 the pole piece on which the magnet is provided. The other 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, vibrations are imparted to the curved diaphragm via the clamping tool.

As shown in FIG. 8 of Patent Document 1, curved guide protrusions are fixed to the opposing surfaces of a pair of side plates provided on the housing, and the inner surfaces of both sides of the curved diaphragm are supported by the respective guide protrusions.

Patent No. 5668233

The universal speaker described in Patent Document 1 has a curved diaphragm formed from a single sheet of paper, plastic, wood, or metal. This makes it difficult to maintain the overall rigidity at an appropriate level, and when vibrations are applied from the driver along the plate surface, unwanted deformation and torsional vibrations are likely to occur. In addition, because the inner surfaces of both sides of the curved diaphragm are supported by the guide protrusions, frictional resistance is likely to occur between the curved diaphragm and the guide protrusions during vibration. This makes the vibration characteristics of the curved diaphragm prone to become unstable.

The present invention aims to solve the above-mentioned problems of the conventional technology and provide a sound-producing device that can improve sound-producing characteristics by optimizing the rigidity of the curved vibrating sheet and suppressing unnecessary deformation and torsional vibration during vibration.

The present invention provides a sound generating device including a vibrating sheet formed of a flexible sheet, a support portion that supports the vibrating sheet, and a drive mechanism that applies a vibration force to the vibrating sheet,
the vibrating sheet has a fixed end portion and a driving end portion located at both ends in a longitudinal direction, and both edge portions extending parallel to each other in the longitudinal direction,
an elastic reinforcing member formed of an elastically deformable foam material is provided, the elastic reinforcing member has a curved surface that is curved toward the vertical direction in a free state, the vibrating sheet that is planar in a free state is curved in the vertical direction, and the curved surfaces of the elastic reinforcing member are fixed along at least both edge portions of the vibrating sheet;
The support portion is provided with an end fixing portion to which the fixed side end portion of the curved vibrating sheet is fixed, a drive mechanism fixing portion that supports the drive mechanism that applies a vibration force to the drive side end portion, and a pair of side wall portions that face both edge portions without restraining both edge portions,
A vibration force is applied from the drive mechanism to the drive side end portion along the sheet surface of the vibrating sheet.

In the sound-producing device of the present invention, it is preferable that both ends of the elastic reinforcing member in the vertical direction are bonded to the support portion and fixed thereto. Also, the elastic reinforcing member may be formed to have a width dimension substantially equal to a width dimension of the vibrating sheet.

In the sound-producing device of the present invention, it is preferable that the edge portion and the side wall portion of the vibrating sheet face each other via a small gap.

The vibrating sheet of the sound-producing device of the present invention is preferably a resin sheet having a metal film formed on the surface thereof.

In the sound-producing device of the present invention, the drive mechanism can be configured to have a flat-wound coil layer formed on the sheet surface of the vibrating sheet at the drive side end, and a magnetic field generating unit fixed to the drive mechanism fixing part and facing the coil layer.

In the sound-producing device of the present invention, an elastic reinforcing member is fixed to the vibrating sheet at least along both edges thereof, so that the rigidity of the vibrating sheet can be set to an optimum value, and the occurrence of excess deformation and torsional vibration can be suppressed, making it easier to stabilize acoustic characteristics such as frequency characteristics. In particular, if the elastic reinforcing member is provided with a curved surface and the vibrating sheet is fixed to the curved surface, the vibrating sheet can be constantly maintained in a curved shape, making it easier to further stabilize the vibration characteristics.

In addition, if the vibrating sheet is a resin sheet with a metal film formed on the surface, such as an FPC, the rigidity of the vibrating sheet alone can be increased, making it possible to prevent unnecessary deformation of the vibrating sheet during vibration.

Furthermore, if the drive mechanism is composed of a flat-wound coil layer formed on the sheet surface of the vibrating sheet and a magnetic field generating unit facing the coil layer, the drive mechanism can be made thin and the coil layer can directly generate a vibration force in a direction along the sheet surface, thereby improving the vibration drive efficiency.

FIG. 2 is a front perspective view of the sound generating device according to the embodiment of the present invention; FIG. 2 is a half-sectional perspective view of the sound-generating device shown in FIG. 1 taken along line II-II; 2 is a cross-sectional view of the sound generating device shown in FIG. 1 taken along line II-II; FIG. 2 is an exploded perspective view of the sound generating device shown in FIG. 3 is a cross-sectional view of the sound generating device shown in FIG. 1 taken along line V-V in FIG. FIG. 6 is an enlarged cross-sectional view of a portion of the sound generating device shown in FIG. 6A and 6B are enlarged cross-sectional views showing a cross section equivalent to that of FIG. 5 , illustrating a modified example of an elastic reinforcing member; FIG. 4 is a cross-sectional view corresponding to FIG. 3, showing a modification of the sound generating device of the present invention;

In the sound production device 1 of the embodiment shown in FIG. 1 etc., the Z1 direction is the front, the Z2 direction is the rear, the Y1 direction is the up, the Y2 direction is the down, the X1 direction is the leftward, and the X2 direction is the rightward.
The sound generating device generates sound pressure mainly in the forward (Z1 direction) and upward (Y1 direction).

As shown in Figs. 1 and 2, the sound generating device 1 has a support portion 2. The support portion 2 is a support housing or a support base. The support portion 2 has a bottom wall portion 3 and a rear wall portion 4. As shown in Fig. 2, the bottom wall portion 3 and the rear wall portion 4 are integrally formed. The support portion 2 has a left wall portion 5 and a right wall portion 6 that face each other in the left-right direction (X1-X2 direction). As shown in Fig. 5, the left wall portion 5 has an opposing inner surface 5a, and the right wall portion 6 has an opposing inner surface 6b. The opposing inner surfaces 5a and 6a are fixed to the left and right side surfaces of the bottom wall portion 3 and the rear wall portion 4, and the left wall portion 5 and the right wall portion 6 face each other in parallel.

As shown in Figures 2 and 3, 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 support part 2, and the upper surface of the support rib 7 serves as the 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 the drive mechanism fixing part 8a. An opening 9, which is a circular hole, is formed in the center of the rear wall 4. The support part 2 is composed of at least the side walls 5 and 6, the end fixing part 7a, and the drive mechanism fixing part 8a.

As shown in FIG. 1, a vibrating sheet 10 is provided between the left side wall 5 and the right side wall 6 of the support portion 2, 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 is greater than the width dimension in the horizontal direction perpendicular to the vertical direction (V1-V2 direction). However, the length dimension of the vibrating sheet 10 in the vertical direction may be smaller than the width dimension in the horizontal direction.

As shown in FIG. 4, the upper end of the vibrating sheet 10 in the vertical direction (V1 direction) is the fixed end 11, and the lower end in the vertical direction (V2 direction) is the driving end 12. The vibrating sheet 10 also has a left edge 13 and a right edge 14 that extend parallel to each other in the vertical direction (V1-V2 direction).

The vibrating sheet 10 is a flexible sheet having elasticity, and is basically composed of a resin sheet formed from 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 from polyimide resin or PET resin. The vibrating sheet 10 is preferably provided with a copper foil layer on almost the entire area except for at least 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, making it easier to prevent unnecessary deformation during vibration.

As shown in FIG. 4 and FIG. 5, a pair of elastic reinforcing members 15 are fixed to the inner surface 10a facing the rear of the vibrating sheet 10 along the left edge 13 and the right edge 14. The elastic reinforcing member 15 is made of a foam material that has a relatively small mass and is elastically deformable, such as a foam rubber material or a foam resin material. The elastic reinforcing member 15 is formed in a curved state in the vertical direction (V1-V2 direction) in a free state, and the surface facing the front (Z1 direction) is a curved surface 15c that is convex toward the front. Note that the elastic reinforcing member 15 may have a depth dimension in the front-back direction (Z1-Z2 direction) that varies depending on the location, as long as it has a curved surface 15c facing the front. The curved surface 15c has a curvature in the vertical direction (V1-V2 direction). Therefore, the vibrating sheet 10 to which the curved surface 15c of the elastic reinforcing member 15 is fixed is curved with a curvature only in the vertical direction, and has no curvature in the horizontal direction perpendicular to the vertical direction.

The vibrating sheet 10 has a planar shape (flat shape) in a free state, and by bonding and fixing the curved surface 15c of the elastic reinforcing member 15 along the left edge 13 and right edge 14 on the inner surface 10a, it becomes possible to maintain a curved shape having a curvature in the vertical direction (V1-V2 direction). As shown in FIG. 5, it is preferable that each elastic reinforcing member 15 and the vibrating sheet 10 are bonded so that the left edge 13 coincides with the left side surface of the elastic reinforcing member 15 and the right edge 14 coincides with the right side surface of the elastic reinforcing member 15. However, the left edge 13 of the vibrating sheet 10 may slightly protrude leftward from the elastic reinforcing member 15, and the right edge 14 may slightly protrude rightward from the elastic reinforcing member 15.

As shown in FIG. 1, a drive mechanism 20 is provided at the lower front of the sound generating device 1. As shown in FIG. 4, the drive mechanism 20 is composed of a coil layer 18 provided at the drive side end 12 of the vibrating sheet 10, and a magnetic field generating unit 21 fixed to the drive mechanism fixing portion 8a of the support unit 2, as also shown in FIG. 2 and FIG. 3.

As shown in FIG. 4, 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 an imaginary center line perpendicular to the sheet surface of the driving side end 12. The coil layer 18 has an upper current conducting portion 18a extending in the left-right direction at the top and a lower current conducting portion 18b extending in the left-right direction at the bottom. In the upper current conducting portion 18a and the lower current conducting portion 18b, voice currents flow in opposite directions in the left-right direction. As shown in FIG. 4, the driving side end 12 of the vibrating sheet 10 has a terminal portion 19a that is conductive to one end of the conductor layer constituting the coil layer, and a terminal portion 19b that is conductive to the other end of the conductor layer. These terminal portions 19a and 19b are formed by etching the copper foil layer of the vibrating sheet 10.

The coil layer 18 is formed by first winding a thin conductor in a plane to form a planar coil structure, and then gluing the coil layer 18 to the sheet surface of the vibrating sheet 10 at the driving side end 12. Alternatively, the copper foil layer of the vibrating sheet 10 made of an FPC may be etched to form the conductor of the planar coil layer 18 with the copper foil layer. The coil layer 18 may be provided only on the surface of the vibrating sheet 10 facing backward (Z2 direction), or only on the surface facing forward (Z1 direction). Alternatively, as shown in FIG. 1, it may be provided on both the surface facing backward and the surface facing forward.

As shown in Figures 2, 3, and 4, the magnetic field generating unit 21 has an opposing yoke 22 made of a magnetic material. The opposing yoke 22 is fixed to the drive mechanism fixing part 8a, which is the tip surface of the bottom wall part 3 of the support part 2. A magnet assembly 26 is provided in front of the opposing yoke 22. The magnet assembly 26 is composed of a lower yoke 23 made of a magnetic material, a magnet 24 stacked on top of it, and an upper yoke 25 made of a magnetic material and located on top of that. In addition, a pair of spacers 27 are interposed between the opposing yoke 22 and the magnet assembly 26. The spacers 27 are also made of a magnetic material, and the left and right spacers 27 are integrally formed with thin plate parts 27a that extend in directions facing each other.

As shown in Figures 2 and 3, the magnetic field generating unit 21 has the thin plate portions 27a of the left and right spacers 27 positioned in front of the opposing yoke 22 fixed to the drive mechanism fixing part 8a, and the magnet assembly 26 positioned further in front of that. The opposing yoke 22, the thin plate portions 27a of the spacers 27, and the magnet assembly 26 are assembled in close contact with each other by the force of the magnetic field emitted from the magnet 24. In addition, by interposing the thin plate portions 27a of the spacers 27 between the opposing yoke 22 and the magnet assembly 26, a minute magnetic gap G is formed between the opposing yoke 22 and the magnet assembly 26 as shown in Figures 2 and 3.

As shown in Figs. 1 and 2, a vibrating sheet 10 is installed between the left side wall 5 and the right side wall 6 of the support part (support housing) 2, and the front (Z1 direction) and the top (Y1 direction) of the support part 2 are blocked by the vibrating sheet 10. At the upper end of the vibrating sheet 10, a fixed side end 11 is bent backward, and the fixed side end 11 is glued and fixed to the end fixing part 7a, which is the upper surface of the support rib 7 of the support part 2. As shown in Figs. 2 and 3, a driving side end 12 provided at the lower end of the vibrating sheet 10 is inserted into the magnetic gap G of the magnetic field generating part 21. The coil layer 18 provided at the driving side end 12 has an upper current conducting part 18a located in the gap where the opposing yoke 22 and the upper yoke 25 face each other, and a lower current conducting part 18b located in the gap where the opposing yoke 22 and the lower yoke 23 face each other.

In the magnetic gap G, a thin elastic sheet, grease, or magnetic rheological fluid is interposed between the opposing yoke 22 and the driving end 12, and between the magnet assembly 26 and the driving end 12. It is preferable to prevent the coil layer 18 and the magnetic field generating unit 21 from directly rubbing against each other.

As shown in FIG. 3, the upper end 15a of the elastic reinforcement member 15 adhered to both the left and right sides of the vibrating sheet 10 is adhered and fixed to the front end surface 7b of the support rib 7 provided on the support portion 2, and the lower end 15b of the elastic reinforcement member 15 is adhered and fixed to the upper surface 22a of the opposing yoke 22. That is, the upper end 15a and the lower end 15b of the elastic reinforcement member 15 are fixed to the support portion 2 side. As shown in FIG. 5 and FIG. 6, a gap δ is formed between the opposing inner surface 6a of the right side wall portion 6 of the support portion 2 and the right edge portion 14 of the vibrating sheet 10 (and the right side surface of the elastic reinforcement member 15). Similarly, a gap δ is formed between the opposing inner surface 5a of the left side wall portion 5 of the support portion 2 and the left edge portion 13 of the vibrating sheet 10 (and the left side surface of the elastic reinforcement member 15). That is, the left side wall portion 5 and the right side wall portion 6 face the edges 13, 14 of the vibrating sheet 10 without restraining the edges 13, 14.

Since the upper end 15a and the lower end 15b of the elastic reinforcing member 15 fixed to the vibrating sheet 10 are fixed to the support part 2 side, the vibrating sheet 10 supported by the support part 2 can maintain its curved shape, and the relative position between the coil layer 18 provided at the driving side end 12 of the vibrating sheet 10 and the magnetic gap G of the magnetic field generating part 21 can be accurately set. In addition, since the elastic reinforcing member 15 is formed of a lightweight foam material that can exert a flexible elastic force, the presence of the elastic reinforcing member 15 does not increase the vibration load of the vibrating sheet 10. In addition, as shown in Figures 5 and 6, a small gap δ is formed between the left side wall part 5 and the right side wall part 6 and the edge parts 13, 14 of the vibrating sheet 10 over almost the entire length of the vibrating sheet 10 in the vertical direction (V1-V2 direction), so that the vibrating sheet 10 can be vibrated without friction occurring between the left side wall part 5 and the right side wall part 6 and the edge parts 13, 14.

Next, the sound generation operation of the sound generation device 1 will be described.
As shown in Figure 4, when a voice current is applied to the coil layer 18 via the terminal portions 19a, 19b provided at the driving side end portion 12 of the vibrating sheet 10, the electromagnetic force generated by the currents flowing in opposite directions to the left and right in the upper current portion 18a and the lower current portion 18b and the magnetic fluxes crossing the upper current portion 18a and the lower current portion 18b in opposite directions within the magnetic gap G causes the vibrating sheet 10 to vibrate in the vertical direction (V1-V2 direction) along the sheet surface.

The vibration of the vibrating sheet 10 generates sound pressure in the space in front (Z1 direction) and above (Y1 direction) of the vibrating sheet 10, and also in the space behind (Z2 direction) the vibrating sheet 10. However, because the rear of the vibrating sheet 10 is divided on the left and right by the left wall portion 5 and the right wall portion 6, and because there is also a bottom wall portion 3 and a rear wall portion 4, the sound pressures in the front and above the spaces and the sound pressure in the rear space are less likely to interfere with each other, and the reproduction capability of low-frequency sounds can be improved.

As shown in Figures 5 and 6, a gap δ is formed between the left and right edge portions 13, 14 of the vibrating sheet 10 and the opposing inner surfaces 5a, 6a of the side wall portions 5, 6. However, since the gap δ is very small, the sound pressure in the space behind the vibrating sheet 10 is unlikely to pass through the gap δ. Therefore, even if the gap δ exists, the sound pressure in the front and upper spaces is unlikely to interfere with the sound pressure in the rear space, and the reproduction ability of the low-frequency range can be maintained at a high level. Moreover, by providing the gap δ, the binding force on the both edge portions 13, 14 of the vibrating sheet 10 is substantially eliminated, and friction is not generated between the both edge portions 13, 14 of the vibrating sheet 10 and the both side wall portions 5, 6, so that the vibrating sheet 10 is unlikely to deform or vibrate due to external forces.

Since the elastic reinforcing member 15 is fixed to the vibrating sheet 10, the rigidity of the vibrating sheet 10 can be increased, and the vibrating sheet 10 can be vibrated in a state where deformation or twisting is unlikely to occur. In addition, since the elastic reinforcing member 15 is formed of a lightweight foam material and can be flexibly deformed, the load when vibrating the vibrating sheet 10 is also small. In particular, since the surface of the elastic reinforcing member 15 that is fixed to the vibrating sheet 10 is a curved surface 15c in advance, and the upper end 15a and the lower end 15b of the elastic reinforcing member 15 are fixed to the support part 2 side, the vibrating sheet 10 can maintain its curved shape even during vibration, and excess vibrations in the thickness direction of the vibrating sheet 10 are unlikely to occur.

Furthermore, the flexible sheet that constitutes the vibrating sheet 10 is an FPC in which a copper foil layer is laminated over the entire surface of a resin sheet (base film) as a metal film, so irregular deformations such as dents and twists are less likely to occur when the vibrating sheet 10 vibrates, making it easier to stabilize the vibration characteristics and improving the reproduced sound quality in the high-frequency range.

As shown in FIG. 4, the coil layer 18 constituting the drive mechanism 20 is wound flat along the sheet surface at the drive side end 12 of the vibrating sheet 10, allowing the drive mechanism 20 to be configured to be thin. In addition, because the coil layer 18 is provided directly on the vibrating sheet 10, the transmission of vibration from the drive mechanism 20 to the vibrating sheet 10 is efficient, which also contributes to power saving.

FIG. 7 shows a modified example of the elastic reinforcing member.
In the sound-producing device 101 shown in Fig. 7(A), an elastic reinforcing member 115 adhered to the rear surface of the vibrating sheet 10 is formed to have a width dimension substantially equal to that of the vibrating sheet 10. However, the elastic reinforcing member 115 has thickened portions 115a in the portions along both edges 13, 14 of the vibrating sheet 10. By providing the thickened portions 115a on both sides, the reinforcing ability of the vibrating sheet 10 is increased, and the elastic reinforcing member 115 can be made lighter. However, as in the sound-producing device 201 shown in Fig. 7 (B) , the thickness dimension of the elastic reinforcing member 215 may be uniform across the entire width.

FIG. 8 shows a modified sound generating device 301 .
This sound generation device 301 is formed by connecting a pair of sound generation devices having the same structure as the sound generation device shown in Fig. 1. In the drive mechanism 320, opposing yokes 22 are provided in front of and behind a common magnet assembly 26, and two magnetic gaps G are formed with the magnet assembly 26 in between. A pair of support parts 2 and vibrating sheets 10 are provided facing each other, and the driving side end portions 12 of the respective vibrating sheets 10 are interposed within the respective magnetic gaps G.

Reference Signs List 1, 101, 201, 301 Sound generating device 2 Support section 5 Left side wall section 6 Right side wall section 7a End fixing section 8a Drive mechanism fixing section 10 Vibrating sheet 11 Fixed side end section 12 Drive side end section 13 Left edge section 14 Right edge section 15 Elastic reinforcing member 15c Curved surface 18 Coil layer 20 Drive mechanism 21 Magnetic field generating section

Claims (4)

A sound generating device including a vibrating sheet formed of a flexible sheet, a support 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 portion and a driving end portion located at both ends in a longitudinal direction, and both edge portions extending parallel to each other in the longitudinal direction,
an elastic reinforcing member formed of an elastically deformable foam material is provided, the elastic reinforcing member has a curved surface that is curved toward the vertical direction in a free state, the vibrating sheet that is planar in a free state is curved in the vertical direction, and the curved surfaces of the elastic reinforcing member are fixed along at least both edge portions of the vibrating sheet;
The support portion is provided with an end fixing portion to which the fixed side end portion of the curved vibrating sheet is fixed, a drive mechanism fixing portion that supports the drive mechanism that applies a vibration force to the drive side end portion, and a pair of side wall portions that face both edge portions without restraining both edge portions,
A sound-producing device, characterized in that a vibration force is applied from the drive mechanism to the drive side end portion along a sheet surface of the vibrating sheet. 2. The sound generating device according to claim 1 , wherein both ends of said elastic reinforcing member in the longitudinal direction are fixed to said support portion by adhesive. 3. The sound generating device according to claim 1 , wherein the elastic reinforcing member is formed to have a width substantially equal to that of the vibrating sheet. 4. The sound generating device according to claim 1, wherein the edge portion and the side wall portion of the vibrating sheet face each other with a small gap therebetween.

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