Diaphragm and musical instrument

Abstract

To provide a diaphragm capable of suppressing expansion and contraction deformation and / or bending deformation.SOLUTION: A diaphragm 1 comprises: a plate-like diaphragm body 10 that is anisotropic in deformation; a long-sized first reinforcement 20 provided to protrude from a first face with respect to the first face 10a of the diaphragm body and extending along the first face in a direction in which the diaphragm body is easily deformed; and a long-sized second reinforcement 30 provided to protrude from a second face with respect to the second face 10b of the diaphragm body and extending along the second face in a direction in which the diaphragm body is easily deformed. Viewed from the thickness direction Z of the diaphragm body, at least a part of the first and second reinforcements in the width direction overlaps at least a part of the first and second reinforcements in the longitudinal direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a diaphragm and a musical instrument. [Background technology]

[0002] 2. Description of the Related Art Conventionally, some musical instruments emit sound by vibrating a diaphragm such as a soundboard with a vibrator. The vibrator operates in response to, for example, an audio signal, and vibrates the diaphragm, thereby generating sound from the diaphragm. Patent Document 1 discloses a structure in which a vibrator having a drive unit and a movable unit is attached to a musical instrument having a diaphragm (soundboard). In this vibrator, the movable unit is electromagnetically connected to a magnetic path forming unit (drive unit) made of a magnet, core, etc., and when a current is passed through the coil in the movable unit, the movable unit moves back and forth in a linear direction relative to the magnetic path forming unit, causing the vibrator to vibrate. The drive unit of the vibrator is fixed to the frame of the musical instrument, etc., and the end of the movable unit in the vibration direction is fixed to the diaphragm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 115482 Summary of the Invention [Problem to be solved by the invention]

[0004] Diaphragms such as soundboards undergo expansion and contraction or bending (flexural deformation) over time due to changes in temperature and humidity. Such expansion and contraction or bending deformation is undesirable for musical instruments that vibrate the diaphragm with a vibrator. For example, when bending deformation occurs in the diaphragm, the normal to a portion of the diaphragm becomes tilted. In this case, the vibration direction of the movable part fixed to a portion of the diaphragm becomes tilted relative to the drive part (magnetic path forming part). In this state, the movable part may rub against the drive part when it vibrates. When the movable part rubs against the drive part, vibrations due to this friction are transmitted to the diaphragm, distorting the sound produced by the diaphragm. In other words, bending deformation of the diaphragm affects the sound production characteristics of the diaphragm when excited by the vibrator.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a diaphragm that can suppress expansion / contraction deformation and / or bending deformation, and a musical instrument equipped with the same. [Means for solving the problem]

[0006] A first aspect of the present invention comprises a plate-shaped diaphragm body that is anisotropic in deformation (stretching and / or bending deformation), a long first reinforcing member that is provided on a first surface of the diaphragm body so as to protrude from the first surface and extends along the first surface in a direction in which the diaphragm body is easily deformed, and a long second reinforcing member that is provided on a second surface of the diaphragm body so as to protrude from the second surface and extends along the second surface in a direction in which the diaphragm body is easily deformed, the first surface and the second surface face in opposite directions in a thickness direction of the diaphragm body, When viewed from the thickness direction of the diaphragm body, at least a portion of the width direction of the first reinforcing material and the second reinforcing material overlaps with at least a portion of the length direction of the first reinforcing material and the second reinforcing material.

[0007] A second aspect of the present invention comprises a plate-shaped diaphragm body that is anisotropic in deformation (stretching and / or bending deformation), a long first reinforcing member that is provided on a first surface of the diaphragm body so as to protrude from the first surface and extends along the first surface in a direction in which the diaphragm body is easily deformed, and a long second reinforcing member that is provided on a second surface of the diaphragm body so as to protrude from the second surface and extends along the second surface in a direction in which the diaphragm body is easily deformed, the first surface and the second surface face in opposite directions in a thickness direction of the diaphragm body,The first reinforcing member and the second reinforcing member are arranged at a distance in the width direction when viewed from the thickness direction of the diaphragm body, and the width direction distance between the first reinforcing member and the second reinforcing member is less than three times the maximum dimension of either the first reinforcing member or the second reinforcing member in a cross section perpendicular to its longitudinal direction.

[0008] A third aspect of the present invention is a musical instrument including the diaphragm and a vibrator that vibrates the diaphragm body. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress expansion / contraction deformation and / or bending deformation of the diaphragm. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a plan view of a musical instrument according to a first embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a front view of the instrument of FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view showing a vibrator provided in the musical instrument of FIGS. [Figure 4] FIG. 3 is a perspective view showing a main part of a diaphragm provided in the musical instrument of FIGS. [Figure 5] 3 is a side view showing a main part of a diaphragm provided in the musical instrument of FIGS. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 7 is a schematic diagram for explaining that bending deformation of the diaphragm shown in FIGS. 4 to 6 can be suppressed. [Figure 8] FIG. 4 is a plan view showing a first modified example of the diaphragm of the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] FIG. 10 is a side view showing a second modified example of the diaphragm of the first embodiment. [Figure 11] FIG. 10 is a side view showing a third modified example of the diaphragm of the first embodiment. [Figure 12] FIG. 10 is a side view showing a fourth modified example of the diaphragm of the first embodiment. [Figure 13] FIG. 10 is a plan view showing a fifth modified example of the diaphragm of the first embodiment. [Figure 14] FIG. 10 is a cross-sectional view showing a sixth modified example of the diaphragm of the first embodiment. [Figure 15] FIG. 10 is a cross-sectional view showing a seventh modified example of the diaphragm of the first embodiment. [Figure 16] FIG. 10 is a cross-sectional view showing an eighth modified example of the diaphragm of the first embodiment. [Figure 17] FIG. 13 is a cross-sectional view showing a ninth modified example of the diaphragm of the first embodiment. [Figure 18] FIG. 10 is a plan view showing a first example of a diaphragm according to a second embodiment of the present invention. [Figure 19] FIG. 10 is a cross-sectional view showing a second example of a diaphragm according to a second embodiment of the present invention. [Figure 20] FIG. 10 is a perspective view showing a main part of a diaphragm according to another embodiment of the present invention. [Figure 21] This is a diagram showing the change in state of a single plate material as it dries or gets wet, where (a) shows the standard state, (b) shows the dry state, and (c) shows the wet state. [Figure 22] This figure shows the change in state of a structure consisting of two stacked boards as they dry or wet, where (a) shows the standard state, (b) shows the dry state, and (c) shows the wet state. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2, the musical instrument MI of this embodiment includes a diaphragm 1 and a vibrator 2 that vibrates the diaphragm 1. The musical instrument MI of this embodiment also includes a frame 3, legs 4, a keyboard 5, and pedals 6, and is configured like a grand piano.

[0012] In the musical instrument MI of this embodiment, the keyboard 5 is arranged on the player's side (front side) of the musical instrument MI. The keyboard 5 is made up of a plurality of keys that are played and operated by the player's fingers.

[0013] The diaphragm 1 is disposed behind the keyboard 5. The diaphragm 1 of this embodiment has a shape in plan view similar to that of a grand piano soundboard. The soundboard is disposed so that its thickness direction faces the vertical direction. Details of the diaphragm 1 will be described later.

[0014] The vibrator 2 is disposed below the diaphragm 1. In this embodiment, a plurality of vibrators 2 (three in the illustrated example) are attached to the diaphragm 1. The plurality of vibrators 2 are disposed at intervals in the left-right direction of the arrangement of the plurality of keys of the keyboard 5. Details of the vibrators 2 will be described later.

[0015] Frame 3 supports diaphragm 1 from below. Frame 3 is fixed to diaphragm 1. In plan view, frame 3 has a frame-like shape that roughly follows the periphery of diaphragm 1. The outer contour of frame 3 shown in FIG. 1 is slightly smaller than the periphery of diaphragm 1 and is formed in a shape similar to that of diaphragm 1.

[0016] The legs 4 extend downward from the frame 3. The pedals 6 are connected to the lower ends of the legs 4 and are disposed on the player's side (front side). The pedals 6 are operated by the player's feet when playing.

[0017] In the musical instrument MI of this embodiment, sound can be generated (emitted) by the vibration exciter 2 vibrating (exciting) the diaphragm 1 based on the performance operation of the keyboard 5 or pedals 6. Note that in the musical instrument MI of this embodiment, sound may be generated by the vibration exciter 2 vibrating the diaphragm 1 based on performance data prepared in advance, for example.

[0018] As shown in Fig. 3, the vibrator 2 of this embodiment is a voice coil type actuator. The up and down direction in Fig. 3 corresponds to the up and down direction in Fig. 2. The vibrator 2 has a magnetic path forming part 100 (drive part) and a movable body 200 (movable part). The movable body 200 has a rod-shaped part 201, a cap 203, a bobbin 204, and a voice coil 205. An annular bobbin 204 is fitted into the lower part of the cap 203 and fixed to the cap 203. The voice coil 205 is formed by a conductive wire wound around the outer circumferential surface of the bobbin 204. The voice coil 205 converts the current flowing through the voice coil 205 into vibration in the magnetic field formed by the magnetic path forming part 100. The cap 203, the bobbin 204, and the voice coil 205 form an electromagnetic engagement part 202 that electromagnetically engages with the magnetic path forming part 100.

[0019] A first end 201a, which is the lower end of rod-shaped portion 201, is connected and fixed to cap 203 of electromagnetic engagement portion 202. Rod-shaped portion 201 extends upward from cap 203. A second end 201b, which is the upper end of rod-shaped portion 201, is fixed to diaphragm 1 via connecting portion 210, which is fixed to the lower surface of diaphragm 1 (for example, second surface 10b of diaphragm main body 10, which will be described later). Connecting portion 210 plays a role in transmitting vibrations of movable body 200 to diaphragm 1 by fixedly connecting second end 201b of rod-shaped portion 201 to diaphragm 1.

[0020] The magnetic path forming portion 100 is configured by arranging a top plate 101, a magnet 102, and a yoke 103 in this order from the top. The electromagnetic engagement portion 202 is supported by a damper 150 so as to be displaceable in the vertical direction (thickness direction of the diaphragm 1) without coming into contact with the magnetic path forming portion 100. The damper 150 is formed into a disk shape using, for example, fiber. The disk-shaped portion of the damper 150 is formed into a bellows-like corrugated shape. The outer peripheral end of the damper 150 is attached to the top plate 101, and the inner peripheral end of the damper 150 is attached to the electromagnetic engagement portion 202. The magnetic path forming portion 100 is supported by a frame 3 (see FIGS. 1 and 2) via a support member (not shown).

[0021] The top plate 101 is made of a soft magnetic material such as soft iron and has a disk shape with a hole in the center. The yoke 103 is made of a soft magnetic material such as soft iron and has a disk-shaped disk portion 103E and a cylindrical portion 103F with a smaller outer diameter than the disk portion 103E, which are integrated with each other by aligning their axes. The outer diameter of the cylindrical portion 103F is smaller than the inner diameter of the top plate 101. The magnet 102 is a doughnut-shaped permanent magnet. The inner diameter of the magnet 102 is larger than the inner diameter of the top plate 101. The axes of the top plate 101, magnet 102, and yoke 103 are aligned, which corresponds to the axis A1 of the magnetic path forming portion 100. This arrangement forms a magnetic path as indicated by the dashed arrow in FIG. 3 . The electromagnetic engagement portion 202 is arranged so that the voice coil 205 is located in the magnetic path space 105, which is the space sandwiched between the top plate 101 and the cylindrical portion 103F. At this time, the electromagnetic engagement portion 202 is positioned in the horizontal direction (left-right direction in FIG. 3 ) by the damper 150 so that the axis A2 of the rod-shaped portion 201 is concentric with the axis A1 of the magnetic path forming portion 100.

[0022] A driving signal based on the performance operation of the keyboard 5 and pedals 6 (see FIG. 1) and performance data is input to the vibrator 2. Specifically, the driving signal is input to the voice coil 205. At this time, the voice coil 205 is subjected to a magnetic force in the magnetic path space 105, and a driving force in the vertical direction corresponding to the waveform indicated by the driving signal acts on the bobbin 204. Therefore, the magnetic path forming part 100 excites the electromagnetic engaging part 202, and the electromagnetic engaging part 202 and the rod-shaped part 201 vibrate vertically together. When the movable body 200 vibrates vertically, the vibration is transmitted to the diaphragm 1 via the connecting part 210, and the diaphragm 1 is vibrated. The vibration of the diaphragm 1 is released into the air, generating sound.

[0023] The diaphragm 1 according to this embodiment will be described below with reference to FIGS. As shown in FIGS. 4 to 6, the diaphragm 1 includes a diaphragm body 10, a first reinforcing member 20, and a second reinforcing member 30. As shown in FIGS.

[0024] The diaphragm body 10 is formed into a plate shape using a material that is anisotropic in linear expansion coefficient and rigidity. The diaphragm body 10 is formed into a flat plate shape when not bent or deformed. The diaphragm body 10 has a first surface 10a and a second surface 10b facing in the thickness direction Z. The first surface 10a and the second surface 10b face opposite each other in the thickness direction Z of the diaphragm body 10. Having anisotropy in the linear expansion coefficient means that the linear expansion coefficient of the first and second surfaces 10a and 10b of the diaphragm body 10 in a predetermined first direction Y along the first and second surfaces 10a and 10b is greater than the linear expansion coefficient in a second direction X perpendicular to the first direction Y along the first and second surfaces 10a and 10b. Also, having anisotropy in rigidity means that the rigidity of the diaphragm body 10 in the first direction Y is greater than the rigidity in the second direction X.

[0025] In the diaphragm body 10, the anisotropy in the linear expansion coefficient and rigidity means that the expansion and contraction deformation is anisotropic. The anisotropy in the expansion and contraction deformation of a plate-like member such as the diaphragm body 10 will be described below.

[0026] As shown in FIG. 21, a single (single) plate P1 expands and contracts in a direction perpendicular to the thickness direction of the plate P1 (the up-and-down direction in FIG. 21) when it dries or wets. Specifically, when the plate P1 dries from the reference state shown in FIG. 21(a) (to the dry state shown in FIG. 21(b)), it contracts in a direction perpendicular to the thickness direction (the left-right direction in FIG. 21). Furthermore, when the plate P1 wets from the reference state (to the wet state shown in FIG. 21(c)), it expands in a direction perpendicular to the thickness direction. The anisotropy in the expansion and contraction deformation of the single plate P1 means that the length by which the plate P1 contracts or expands relative to the reference state when it dries or wets is different in a first orthogonal direction perpendicular to the thickness direction of the plate P1 and a second orthogonal direction perpendicular to both the thickness direction and the first orthogonal direction of the plate P1.

[0027] Bending deformation due to expansion and contraction deformation of the diaphragm body 10 refers to deformation in which the diaphragm body 10 flexes so that the first surface 10a and the second surface 10b of the diaphragm body 10 are curved. The diaphragm body 10 has anisotropy in bending deformation (flexural deformation) due to the anisotropy in the linear expansion coefficient and rigidity described above. The anisotropy in bending deformation due to expansion and contraction deformation of the diaphragm body 10 means that the first direction Y is "the direction in which the diaphragm body 10 is more likely to expand and contract" and "the direction in which the diaphragm body 10 is more likely to bend" compared to the second direction X. Bending deformation of a plate-like member such as the diaphragm body 10 will be described below.

[0028] Bending deformation of a plate-like member such as diaphragm main body 10 can occur, for example, when plate-like member PB is formed by stacking two single plate materials P2 and P3, each of which has anisotropic expansion and contraction deformation, as shown in Fig. 22. Specifically, bending deformation occurs in plate-like member PB when the directions in which the two overlapping plate materials P2 and P3 are prone to expansion and contraction deformation are perpendicular to each other. In the plate-like member PB shown in Fig. 22, the direction in which the upper plate material P2 is prone to expansion and contraction deformation is the left-right direction, and the direction in which the lower plate material P3 is prone to expansion and contraction deformation is the direction perpendicular to the plane of the paper.

[0029] When the plate-like member PB dries from the reference state shown in FIG. 22(a) (to the dried state shown in FIG. 22(b)), the upper plate P2 actively shrinks in the left-right direction, but the lower plate P3 does not actively shrink in the left-right direction. As a result, the upper surface of the upper plate P2 shrinks in the left-right direction, but the left-right shrinkage of the lower surface of the upper plate P2, where the lower plate P3 overlaps, is suppressed by the lower plate P3. As a result, in the dried state shown in FIG. 22(b), the plate-like member PB bends and deforms so that it is convex downward.

[0030] On the other hand, when the plate-like member PB becomes wet from the standard state shown in FIG. 22(a) (to the wet state shown in FIG. 22(c)), the upper plate P2 actively expands in the left-right direction, but the lower plate P3 does not actively expand in the left-right direction. As a result, the upper surface of the upper plate P2 expands in the left-right direction, but the left-right expansion of the lower surface of the upper plate P2, which overlaps the lower plate P3, is suppressed by the lower plate P3. As a result, in the wet state shown in FIG. 22(c), the plate-like member PB bends and deforms so that it becomes convex upward.

[0031] In the drawings showing the diaphragm 1 (FIGS. 4 to 6, etc.), the first direction Y and the second direction X are shown as straight lines, assuming that the diaphragm body 10 is not bent or deformed.

[0032] The diaphragm body 10 of this embodiment is made of wood with a grain extending along the first surface 10a and the second surface 10b. The grain direction of the diaphragm body 10 corresponds to the second direction X described above. A wooden diaphragm body 10 is prone to bending and deformation in a direction perpendicular to the grain direction (i.e., the first direction Y). Note that the diaphragm body 10 is not limited to wood and may be made of other materials such as resin or paper.

[0033] The first reinforcing member 20 is provided on the first surface 10a of the diaphragm body 10 so as to protrude from the first surface 10a in the thickness direction Z of the diaphragm body 10. The first reinforcing member 20 is formed in an elongated shape extending in the first direction Y along the first surface 10a of the diaphragm body 10. The length dimension L1 of the first reinforcing member 20 is sufficiently larger than the height dimension H1 of the first reinforcing member 20 and the width dimension W1 of the first reinforcing member 20.

[0034] In this embodiment, the first reinforcing member 20 extends linearly along the first direction Y. That is, the first reinforcing member 20 extends in a direction perpendicular to the second direction X, which is the grain direction of the diaphragm main body 10. In this embodiment, the length dimension L1 of the first reinforcing member 20 is the dimension along the first direction Y. The width dimension W1 of the first reinforcing member 20 is the dimension in the width direction of the first reinforcing member 20, which is perpendicular to the longitudinal direction of the first reinforcing member 20 along the first surface 10a. In this embodiment, the width direction of the first reinforcing member 20 corresponds to the second direction X. Furthermore, the height dimension H1 of the first reinforcing member 20 corresponds to the thickness direction Z of the diaphragm main body 10.

[0035] In this embodiment, the width dimension W1 of the first reinforcing member 20 is constant throughout the first reinforcing member 20 in the longitudinal direction. The height dimension H1 of the first reinforcing member 20 may be constant over the entire length of the first reinforcing member 20. In this embodiment, as shown in FIG. 5 , the height dimension H1 of the first reinforcing member 20 varies depending on the position in the length of the first reinforcing member 20. Specifically, the height dimension H1 of the first reinforcing member 20 is greatest at the middle portion of the first reinforcing member 20 in the length direction. Furthermore, the height dimension H1 of the first reinforcing member 20 decreases from the middle portion of the first reinforcing member 20 toward both ends in the length direction. The height dimension H1 of the first reinforcing member 20 is preferably greater than the thickness dimension H3 of the diaphragm main body 10, and more preferably, for example, three times the thickness dimension H3 of the diaphragm main body 10.

[0036] As shown in Fig. 6, the cross-sectional shape of the first reinforcing material 20 perpendicular to the longitudinal direction of the first reinforcing material 20 is a rectangle in which the height dimension H1 is longer than the width dimension W1. Therefore, the cross-sectional shape of the first reinforcing material 20 is line-symmetric in the width direction. The dashed dotted line indicated by the symbol WC1 in Fig. 6 is the center line WC1 of the first reinforcing material 20 in the width direction of the first reinforcing material 20. The cross-sectional shape of the first reinforcing material 20 is line-symmetric about the center line WC1.

[0037] 4 to 6, the second reinforcing member 30 is provided on the second surface 10b of the diaphragm main body 10 so as to protrude from the second surface 10b in the thickness direction Z of the diaphragm main body 10. In other words, the second reinforcing member 30 protrudes from the diaphragm main body 10 in the opposite direction to the first reinforcing member 20. The second reinforcing member 30 is formed in an elongated shape extending in the first direction Y along the second surface 10b of the diaphragm main body 10. The length dimension L2 of the second reinforcing member 30 is sufficiently larger than the height dimension H2 of the second reinforcing member 30 and the width dimension W2 of the second reinforcing member 30.

[0038] The second reinforcing member 30 of this embodiment extends linearly along the first direction Y, similar to the first reinforcing member 20. That is, the second reinforcing member 30 extends in a direction perpendicular to the second direction X, which is the grain direction of the diaphragm main body 10. In this embodiment, the length dimension L2 of the second reinforcing member 30 is the dimension along the first direction Y. The width dimension W2 of the second reinforcing member 30 is the dimension in the width direction of the second reinforcing member 30, which is perpendicular to the longitudinal direction of the second reinforcing member 30 along the second surface 10b. In this embodiment, the width direction of the second reinforcing member 30 corresponds to the second direction X. Furthermore, the height dimension H2 of the second reinforcing member 30 corresponds to the thickness direction Z of the diaphragm main body 10.

[0039] The second reinforcing member 30 may be formed in a shape different from that of the first reinforcing member 20, for example. The shape of the second reinforcing member 30 in this embodiment is the same as that of the first reinforcing member 20. That is, the width dimension W2 of the second reinforcing member 30 is constant throughout the entire length of the second reinforcing member 30. Furthermore, the height dimension H2 of the second reinforcing member 30 varies depending on the position in the length of the second reinforcing member 30. As with the first reinforcing member 20, the height dimension H2 of the second reinforcing member 30 is preferably larger than the thickness dimension H3 of the diaphragm main body 10, and more preferably, for example, three times the thickness dimension H3 of the diaphragm main body 10.

[0040] 6, the cross-sectional shape of the second reinforcing member 30 perpendicular to the longitudinal direction of the second reinforcing member 30 is a rectangle in which the height dimension H2 is longer than the width dimension W2. Therefore, the cross-sectional shape of the second reinforcing member 30 is line-symmetric in the width direction. The dashed dotted line indicated by the symbol WC2 in FIG. 6 is the center line WC2 of the second reinforcing member 30 in the width direction of the second reinforcing member 30. The cross-sectional shape of the second reinforcing member 30 is line-symmetric about the center line WC2.

[0041] In this embodiment, the rigidity of the first reinforcing member 20 and the second reinforcing member 30 is equal to each other. The specific gravity of the first reinforcing member 20 and the second reinforcing member 30 is equal to or less than the specific gravity of the diaphragm main body 10. The first reinforcing member 20 and the second reinforcing member 30 are made of the same material.

[0042] In this embodiment, the material of both the first reinforcing material 20 and the second reinforcing material 30 is wood. The grain direction of the first reinforcing material 20 and the second reinforcing material 30 is the same. The grain direction of the first reinforcing material 20 and the grain direction of the second reinforcing material 30 may be completely aligned or may be slightly inclined from each other. Note that the first reinforcing material 20 and the second reinforcing material 30 are not limited to wood, and may be made of other materials such as resin (e.g., CFRP).

[0043] 6, the cross-sectional shape of the first reinforcing member 20 and the cross-sectional shape of the second reinforcing member 30 are the same (i.e., rectangular). In addition, the cross-sectional area of ​​the first reinforcing member 20 perpendicular to the longitudinal direction of the first reinforcing member 20 and the cross-sectional area of ​​the second reinforcing member 30 perpendicular to the longitudinal direction of the second reinforcing member 30 are equal to each other. Furthermore, the cross-sectional shape of the first reinforcing member 20 and the cross-sectional shape of the second reinforcing member 30 are the same, including their sizes. As a result, the cross-sectional shape of the first reinforcing member 20 and the cross-sectional shape of the second reinforcing member 30 are line-symmetrical with each other in the thickness direction Z of the diaphragm main body 10. The dashed dotted line indicated by the symbol HC3 in Fig. 6 is the center line HC3 of the diaphragm main body 10 in the thickness direction Z of the diaphragm main body 10. The cross-sectional shape of the first reinforcing member 20 and the cross-sectional shape of the second reinforcing member 30 are formed line-symmetrical with each other about the center line HC3.

[0044] In addition, in this embodiment, as shown in FIG. 5, the shapes of the first and second reinforcing members 20, 30 as viewed in the width direction (second direction X) of the first and second reinforcing members 20, 30 are also symmetrical to each other with respect to the center line HC3 of the diaphragm main body 10 as the axis.

[0045] The first reinforcing member 20 and the second reinforcing member 30 overlap each other when viewed from the thickness direction Z of the diaphragm body 10. In this embodiment, as shown in FIG. 5 , the length dimension L1 of the first reinforcing member 20 and the length dimension L2 of the second reinforcing member 30 are equal to each other. Furthermore, the positions of the first and second reinforcing members 20, 30 in their longitudinal directions (first direction Y) coincide with each other. Furthermore, the longitudinal directions of the first and second reinforcing members 20, 30 are parallel to each other. Therefore, the first reinforcing member 20 and the second reinforcing member 30 overlap over their entire lengths. Furthermore, the first reinforcing member 20 and the second reinforcing member 30 are arranged so as to be line-symmetrical to each other in their longitudinal directions.

[0046] In Fig. 5, the dashed dotted line indicated by the symbol LC1 is the center line LC1 of the first reinforcing member 20 in the longitudinal direction of the first reinforcing member 20. Furthermore, the dashed dotted line indicated by the symbol LC2 is the center line LC2 of the second reinforcing member 30 in the longitudinal direction of the second reinforcing member 30. In Fig. 5, the center lines LC1 and LC2 of the first and second reinforcing members 20, 30 coincide with each other. As a result, the first reinforcing member 20 and the second reinforcing member 30 are arranged so as to be line-symmetrical with each other in the longitudinal direction.

[0047] 6, in this embodiment, the positions of the first reinforcing member 20 and the second reinforcing member 30 in the width direction are aligned with each other. That is, the center lines WC1 and WC2 of the first and second reinforcing members 20 and 30 in the width direction are aligned with each other. Furthermore, the width dimensions W1 and W2 of the first and second reinforcing members 20 and 30 are equal to each other. Therefore, the first reinforcing member 20 and the second reinforcing member 30 overlap each other over the entire width direction.

[0048] In this embodiment, the cross-sectional shape including both the first and second reinforcing members 20, 30 in a cross section perpendicular to the longitudinal direction (first direction Y) of the first and second reinforcing members 20, 30 is line-symmetric in the width direction. That is, the cross-sectional shape including both the first and second reinforcing members 20, 30 is line-symmetric about the center lines WC1, WC2 of the first and second reinforcing members 20, 30 in the width direction.

[0049] In this embodiment, it is preferable that in the thickness direction Z of the diaphragm body 10, the length TH from the tip of the first reinforcing member 20 in the protruding direction to the tip of the second reinforcing member 30 in the protruding direction (total length TH) is five times or more the thickness dimension H3 of the diaphragm body 10. The above-mentioned total length TH corresponds to the sum of the height dimensions H1, H2 of the first and second reinforcing members 20, 30 and the thickness dimension H3 of the diaphragm body 10.

[0050] In this embodiment, in each of the reinforcing members 20, 30 (reinforcing members constituting the first reinforcing member 20 and the second reinforcing member 30), the maximum height dimension of the reinforcing members 20, 30 is HMAX, the maximum width dimension of the reinforcing members 20, 30 is WMAX, and 0.5≦HMAX / WMAX≦4.0 It is more preferable that HMAX / WMAX is, for example, about 2.0.

[0051] In the musical instrument MI shown in Fig. 1, the reinforcing members 20, 30 of the diaphragm 1 are preferably arranged so as not to interfere with the mounting position of the vibrator 2 relative to the diaphragm main body 10. Furthermore, as illustrated in Fig. 1, the reinforcing members 20, 30 of the diaphragm 1 may be arranged inside the frame 3 when viewed from the thickness direction Z of the diaphragm main body 10. Furthermore, as illustrated in Fig. 1, multiple pairs of first reinforcing members 20 and second reinforcing members 30 may be arranged at intervals in the width direction of the reinforcing members 20, 30. The multiple pairs of first reinforcing members 20 and second reinforcing members 30 may be parallel to each other as illustrated in Fig. 1, but they may not be parallel, for example.

[0052] As described above, in the diaphragm 1 of this embodiment, the first surface 10a of the diaphragm main body 10 is provided with an elongated first reinforcing member 20 that protrudes from the first surface 10a and extends in a direction (first direction Y) in which the diaphragm main body 10 is likely to deform (expand / contract and / or bend). The second surface 10b of the diaphragm main body 10 is provided with an elongated second reinforcing member 30 that protrudes from the second surface 10b and extends in a direction in which the diaphragm main body 10 is likely to deform (expand / contract and / or bend). Furthermore, the first reinforcing member 20 and the second reinforcing member 30 overlap when viewed from the thickness direction Z of the diaphragm main body 10. This allows the first and second reinforcing members 20, 30 to effectively prevent the diaphragm main body 10 from expanding or contracting in a direction in which it is likely to expand or contract, or from bending in a direction in which it is likely to bend. This point will be explained below.

[0053] 7, when stress (force indicated by arrow F1) acts on diaphragm body 10 to shrink in a direction (first direction Y) in which diaphragm body 10 is prone to expansion and contraction deformation due to drying or the like, first reinforcing member 20 suppresses the stress generated on first surface 10a side of diaphragm body 10, thereby suppressing shrinkage of the portion of diaphragm body 10 on first surface 10a side. Also, second reinforcing member 30 suppresses the stress generated on second surface 10b side of diaphragm body 10, thereby suppressing shrinkage of the portion of diaphragm body 10 on second surface 10b side. Furthermore, although not shown, when stress acts on diaphragm body 10 to stretch it in a direction (first direction Y) in which it is prone to contraction and deformation due to wetting or the like, first reinforcing member 20 suppresses the stress generated on first surface 10a side of diaphragm body 10, thereby suppressing the stretching of the part of diaphragm body 10 on first surface 10a side. Furthermore, second reinforcing member 30 suppresses the stress generated on second surface 10b side of diaphragm body 10, thereby suppressing the stretching of the part of diaphragm body 10 on second surface 10b side. As a result, it is possible to effectively suppress expansion and contraction deformation of the diaphragm body 10 in the first direction Y due to drying or wetting of the diaphragm body 10. It is also possible to effectively suppress the diaphragm body 10 from bending in a direction in which it is more likely to bend due to the expansion and contraction deformation.

[0054] Furthermore, in the diaphragm 1 of this embodiment, the diaphragm main body 10 is made of wood having a wood grain extending along the first surface 10a and the second surface 10b. Therefore, the diaphragm main body 10 is prone to expand and contract in a direction perpendicular to the wood grain direction (first direction Y). In contrast, the first and second reinforcing members 20, 30 extend in directions intersecting the wood grain direction so that they overlap each other. This allows the first and second reinforcing members 20, 30 to effectively suppress expansion and contraction of the diaphragm main body 10 in the direction perpendicular to the wood grain direction.

[0055] Furthermore, in the diaphragm 1 of this embodiment, the first and second reinforcing members 20, 30 have the same rigidity. This allows the forces for suppressing expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to the expansion and contraction deformation to be made uniform (or equal) between the first reinforcing member 20 and the second reinforcing member 30. This makes it possible to more effectively suppress expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to the expansion and contraction deformation.

[0056] Furthermore, in the diaphragm 1 of this embodiment, the first and second reinforcing members 20, 30 are made of the same material. Therefore, simply by forming the first and second reinforcing members 20, 30 to have the same shape and size, the forces that suppress expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to the expansion and contraction deformation can be easily made uniform (or equal) between the first reinforcing member 20 and the second reinforcing member 30.

[0057] Furthermore, in the diaphragm 1 of this embodiment, the first and second reinforcing members 20, 30 have the same rigidity and material, and the cross-sectional areas of the first and second reinforcing members 20, 30 perpendicular to the longitudinal direction are equal to each other. Therefore, even if the cross-sectional shapes of the first reinforcing member 20 and the second reinforcing member 30 are different, the characteristics of the reinforcing members 20, 30 in terms of longitudinal expansion and contraction deformation in response to changes in temperature and humidity are the same for the first reinforcing member 20 and the second reinforcing member 30. This prevents differences in the effect of suppressing expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to expansion and contraction deformation between the first surface 10a and the second surface 10b of the diaphragm main body 10. As a result, expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to expansion and contraction deformation can be suitably suppressed.

[0058] Furthermore, in the diaphragm 1 of this embodiment, the first reinforcing member 20 and the second reinforcing member 30 are arranged so as to be line-symmetrical with each other in the longitudinal direction of the first and second reinforcing members 20, 30. As a result, even if the length dimension L1 of the first reinforcing member 20 and the second reinforcing member 30 differs or even if the arrangement of the first reinforcing member 20 and the second reinforcing member 30 differs, it is possible to effectively suppress expansion / contraction deformation of the diaphragm main body 10 and bending deformation due to the expansion / contraction deformation.

[0059] In the diaphragm 1 of this embodiment, when the total length TH from the tip of the first reinforcing member 20 in the protruding direction to the tip of the second reinforcing member 30 in the protruding direction is five times or more the thickness dimension H3 of the diaphragm main body 10, the second moment of area of ​​the two reinforcing members 20, 30 in the thickness direction Z of the diaphragm main body 10 becomes large relative to the diaphragm main body 10. As a result, the two reinforcing members 20, 30 can effectively suppress the expansion and contraction deformation of the diaphragm main body 10 and bending deformation due to the expansion and contraction deformation.

[0060] Furthermore, in the diaphragm 1 of this embodiment, when the ratio HMAX / WMAX of the maximum height dimension HMAX to the maximum width dimension WMAX of the reinforcing members 20, 30 (the reinforcing members constituting the first and second reinforcing members 20, 30) is 0.5 or more, warping (vertical warping) of the reinforcing members 20, 30 in the thickness direction Z of the diaphragm main body 10 can be suppressed. Furthermore, when HMAX / WMAX is 4.0 or less, warping (lateral warping) of the reinforcing members 20, 30 in the width direction of the reinforcing members 20, 30 can be suppressed. In other words, the second moments of area of ​​the reinforcing members 20, 30 in both the thickness direction Z of the diaphragm main body 10 and the width direction of the reinforcing members 20, 30 can be kept well balanced. This effectively suppresses the occurrence of vertical warping or lateral warping of the reinforcing members 20, 30, and as a result, effectively suppresses the occurrence of expansion / contraction deformation and bending deformation due to expansion / contraction deformation of the diaphragm main body 10 due to the vertical warping or lateral warping of the reinforcing members 20, 30.

[0061] Furthermore, when HMAX / WMAX is about 2 (height dimensions H1, H2 of reinforcing members 20, 30 are about twice width dimensions W1, W2), the rigidity of reinforcing members 20, 30 relative to the rigidity of diaphragm main body 10 (specific rigidity of reinforcing members 20, 30) can be effectively increased. This makes it possible to more effectively suppress the expansion and contraction deformation of diaphragm main body 10. Furthermore, it is possible to more effectively suppress the tendency of diaphragm main body 10 to bend in a direction in which it is more likely to bend due to the expansion and contraction deformation.

[0062] Furthermore, in the diaphragm 1 of this embodiment, even when the specific gravity of the reinforcing members 20, 30 is equal to or less than the specific gravity of the diaphragm main body 10, the specific rigidity of the reinforcing members 20, 30 can be increased. This makes it possible to more effectively suppress the expansion and contraction deformation of the diaphragm main body 10. It also makes it possible to more effectively suppress the diaphragm main body 10 from bending in a direction in which it is more likely to bend due to the expansion and contraction deformation.

[0063] Furthermore, in the diaphragm 1 of this embodiment, even when the height dimension of the reinforcing members 20, 30 is three times the thickness dimension H3 of the diaphragm main body 10, the specific rigidity of the reinforcing members 20, 30 can be increased. This makes it possible to more effectively suppress the expansion and contraction deformation of the diaphragm main body 10. It also makes it possible to more effectively suppress the diaphragm main body 10 from bending in a direction in which it is more likely to bend due to the expansion and contraction deformation.

[0064] According to the musical instrument MI of this embodiment, the vibrator 2 is attached to the diaphragm 1 whose expansion, contraction, and bending deformations are effectively suppressed as described above. Therefore, it is possible to suppress changes in the sound generation characteristics of the diaphragm 1 caused by the vibrator 2 due to expansion, contraction, and bending deformations of the diaphragm 1.

[0065] In the first embodiment, as shown in Figures 8 and 9, for example, the first reinforcing member 20 and the second reinforcing member 30 may only partially overlap in the width direction when viewed from the thickness direction Z of the diaphragm main body 10. In the configuration illustrated in Figures 8 and 9, the center lines WC1 and WC2 of the first and second reinforcing members 20 and 30 in the width direction are offset from each other, so that only partially overlap in the width direction of the first reinforcing member 20 and the second reinforcing member 30. In Figure 8, the overlapping area between the first reinforcing member 20 and the second reinforcing member 30 is indicated by linear hatching.

[0066] 8, the length dimension L1 of the first reinforcing material 20 is shorter than the length dimension L2 of the second reinforcing material 30, so that the width direction portions of the first and second reinforcing materials 20 and 30 overlap over the entire length of the first reinforcing material 20. 8 and 9, similarly to the above-described embodiment, the expansion and contraction deformation of the diaphragm body 10 and bending deformation due to the expansion and contraction deformation can be effectively suppressed.

[0067] However, it is more preferable that the ratio of the size of the overlapping portions of the first and second reinforcing members 20, 30 in the width direction to one width dimension of the reinforcing members 20, 30 is large. The larger the ratio of the size of the overlapping portions of the first and second reinforcing members 20, 30 in the width direction to one width dimension of the reinforcing members 20, 30, the more effectively the diaphragm body 10 can be suppressed from expanding and contracting deformation and bending deformation due to the expanding and contracting deformation. In other words, it is most preferable that the first and second reinforcing members 20, 30 overlap over the entirety of one width direction, as illustrated in FIG.

[0068] In the first embodiment, the length dimensions L1, L2 of the first and second reinforcing members 20, 30 may be different from each other, as shown in Fig. 10, for example. In Fig. 10, the length dimension L1 of the first reinforcing member 20 is shorter than the length dimension L2 of the second reinforcing member 30. In the configuration illustrated in Fig. 10, the center line LC1 of the first reinforcing member 20 and the center line LC2 of the second reinforcing member 30 in the longitudinal direction coincide with each other. In other words, the first reinforcing member 20 and the second reinforcing member 30 are arranged so as to be line-symmetrical with each other in the longitudinal direction. Therefore, the same effects as those of the first embodiment described above can be obtained.

[0069] In the first embodiment, the first reinforcing member 20 and the second reinforcing member 30 may be arranged in different ways, as shown in FIG. 11 , for example. In FIG. 11 , one first reinforcing member 20 is arranged on the first surface 10a of the diaphragm main body 10, while the second reinforcing member 30 is arranged by dividing the second reinforcing member 30 into multiple pieces (three pieces in FIG. 11 ) in the longitudinal direction. In the configuration illustrated in FIG. 11 , the center line LC1 of the first reinforcing member 20 and the center line LC2 of the second reinforcing member 30 in the longitudinal direction coincide with each other. That is, the first reinforcing member 20 and the second reinforcing member 30 are arranged so as to be line-symmetrical with each other in the longitudinal direction. Therefore, the same effects as those of the first embodiment described above can be obtained. In FIG. 11, the total length dimension L2 of the multiple divided second reinforcing members 30 is equal to the length dimension L1 of the first reinforcing member 20, but may be different, for example.

[0070] In the first embodiment, the first reinforcing member 20 and the second reinforcing member 30 may be positioned offset from each other in the longitudinal direction (first direction Y) of the reinforcing members 20, 30, as shown in FIG. 12 , for example. In this case, it is preferable that the distance D1 (first distance D1) between the first end 21 of the first reinforcing member 20 and the first end 31 of the second reinforcing member 30, which are located on one side in the longitudinal direction, and the distance D2 (second distance D2) between the second end 22 of the first reinforcing member 20 and the second end 32 of the second reinforcing member 30, which are located on the other side in the longitudinal direction, are both 20% or less of the length of the longer of the first and second reinforcing members 20, 30. In the configuration illustrated in FIG. 12 , the length dimension L1 of the first reinforcing member 20 is longer than the length dimension L2 of the second reinforcing member 30. For this reason, it is preferable that the first distance D1 and the second distance D2 are 20% or less of the length dimension L1 of the first reinforcing member 20.

[0071] In the first embodiment, as shown in FIG. 13 , the first and second reinforcing members 20 and 30 may overlap in part in the longitudinal direction when viewed from the thickness direction Z of the diaphragm body 10. In FIG. 13 , the first and second reinforcing members 20 and 30 cross each other, causing the first and second reinforcing members 20 and 30 to overlap in the middle of the longitudinal direction. In FIG. 13 , the overlapping region of the first reinforcing member 20 and the second reinforcing member 30 is indicated by linear hatching. In FIG. 13 , the first and second reinforcing members 20 and 30 overlap over their entire widths, but, for example, only a part in the width direction of the first and second reinforcing members 20 and 30 may overlap. Furthermore, the first and second reinforcing members 20 and 30 may overlap, for example, at the longitudinal ends of the first and second reinforcing members 20 and 30.

[0072] Even if the first and second reinforcing members 20, 30 are configured to overlap in part of their longitudinal direction, as in the first embodiment, the first and second reinforcing members 20, 30 can suppress the expansion and contraction deformation of the vibration plate body 10 in the first direction Y (the direction in which the vibration plate body 10 is likely to expand and contract) and the tendency for the vibration plate body 10 to bend in the first direction Y (the direction in which the vibration plate body 10 is likely to bend and deform). However, it is preferable that the ratio of the length of the overlapping portion of the first and second reinforcing members 20, 30 to the entire length of one of the reinforcing members 20, 30 be large, and more preferably be 50% or more, for example. The larger the ratio of the length of the overlapping portion of the first and second reinforcing members 20, 30 to the entire length of one of the reinforcing members 20, 30, the more effectively the expansion / contraction deformation and bending deformation of the diaphragm main body 10 can be suppressed. In other words, it is most preferable that the first and second reinforcing members 20, 30 overlap over the entire length of at least one of them, as illustrated in Figures 6 and 8.

[0073] In the first embodiment, the first and second reinforcing members 20, 30 may intersect with the first direction Y (the direction in which the diaphragm body 10 is likely to deform (expand, contract, and / or bend)), as shown in Fig. 13, for example. However, it is preferable that the inclination angle of the longitudinal direction of the first and second reinforcing members 20, 30 with respect to the first direction Y is smaller than the inclination angle of the longitudinal direction of the first and second reinforcing members 20, 30 with respect to the second direction X. In other words, it is preferable that the first and second reinforcing members 20, 30 extend mainly in the first direction Y.

[0074] Furthermore, the first and second reinforcing members 20, 30 are not limited to extending linearly mainly in the first direction Y, and may be formed, for example, in an elongated shape extending mainly in the first direction Y while curving (snakes) in the second direction X. In Fig. 13, the first reinforcing member 20 extends linearly, and the second reinforcing member 30 extends mainly in the first direction Y while curving (snakes) in the second direction X.

[0075] In the first embodiment, the width dimensions of the reinforcing members 20, 30 (first and second reinforcing members 20, 30) may vary, for example, in the longitudinal direction of the reinforcing members 20, 30. In Fig. 13, the width dimension of the first reinforcing member 20 increases from one side to the other in the longitudinal direction (from left to right in Fig. 13). Note that in Fig. 13, the width dimension of the second reinforcing member 30, which meanders in the second direction X, is constant throughout the entire longitudinal direction of the second reinforcing member 30.

[0076] In the first embodiment, the cross-sectional shape of the reinforcing members 20, 30 perpendicular to the longitudinal direction of the reinforcing members 20, 30 is not limited to a rectangle and may be any shape. The cross-sectional shape of the reinforcing members 20, 30 may be formed into a shape having a constriction at the base end of the reinforcing members 20, 30 in the height direction (thickness direction Z), as shown in FIG. 14, for example. The cross-sectional shapes of the reinforcing members 20, 30 illustrated in FIG. 14 are line-symmetric in the width direction, similar to the first embodiment. Also, in FIG. 14, the cross-sectional shapes of the first reinforcing member 20 and the second reinforcing member 30 are line-symmetric with each other in the thickness direction Z of the diaphragm body 10, similar to the first embodiment.

[0077] In the first embodiment, as shown in Figures 15 and 16, for example, the cross-sectional shapes of the reinforcing members 20, 30 perpendicular to the longitudinal direction of the reinforcing members 20, 30 may be different between the first reinforcing member 20 and the second reinforcing member 30. In Figure 15, the cross-sectional shape of the first reinforcing member 20 is rectangular, and the cross-sectional shape of the second reinforcing member 30 has a constriction at the base end of the second reinforcing member 30 in the height direction, as in Figure 14. In Figure 16, the cross-sectional shape of the first reinforcing member 20 is rectangular, and the cross-sectional shape of the second reinforcing member 30 is triangular. Even with this configuration, if the cross-sectional areas of the first and second reinforcing members 20, 30 perpendicular to the longitudinal direction are equal to each other, the same effect as in the first embodiment described above can be obtained.

[0078] In the first embodiment, as shown in Fig. 17, for example, in a cross section of the reinforcing members 20, 30 perpendicular to the longitudinal direction of the reinforcing members 20, 30, the height dimension H1 of the first reinforcing member 20 and the height dimension H2 of the second reinforcing member 30 may be different from each other. In Fig. 17, the height dimension H2 of the second reinforcing member 30 is smaller than the height dimension H1 of the first reinforcing member 20. With this configuration, when the vibrator 2 is attached to the second surface 10b of the diaphragm main body 10, it is possible to effectively prevent the vibrator 2 from interfering with the second reinforcing member 30, which has a smaller height dimension. Furthermore, even if the height dimension H1 of the first reinforcing material 20 and the height dimension H2 of the second reinforcing material 30 are different from each other as illustrated in Figure 17, if the cross-sectional areas of the first and second reinforcing materials 20, 30 perpendicular to the longitudinal direction are equal to each other, the same effect as in the first embodiment described above can be obtained.

[0079] Second Embodiment Next, a second embodiment of the present invention will be described mainly with reference to Figures 18 and 19. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0080] Fig. 18 shows a first example of a diaphragm 1C of the second embodiment. Fig. 19 shows a second example of a diaphragm 1D of the second embodiment. The diaphragms 1C and 1D of the second embodiment are applicable to the musical instrument MI shown in Figs. 1 and 2, similar to the diaphragm 1 of the first embodiment. 18 and 19 each include, similarly to the first embodiment, a diaphragm body 10, a first reinforcing member 20, and a second reinforcing member 30. The diaphragm body 10 is similar to that of the first embodiment.

[0081] In the diaphragm 1C shown in FIG. 18, the first reinforcing member 20 is formed in the same manner as the first reinforcing member 20 illustrated in FIG. 13. That is, the first reinforcing member 20 extends linearly mainly in the first direction Y, and its width increases from one side to the other in the longitudinal direction (from left to right in FIG. 13). Furthermore, the second reinforcing member 30 is formed in the same manner as the second reinforcing member 30 illustrated in FIG. 13. That is, the second reinforcing member 30 extends mainly in the first direction Y while curving (snakes) in the second direction X. The width of the second reinforcing member 30 is constant throughout the entire longitudinal direction of the second reinforcing member 30. The maximum dimension W1MAX in the width direction of the first reinforcing member 20 (maximum width dimension W1MAX) is greater than the width of the second reinforcing member 30.

[0082] 19, the first reinforcing member 20 and the second reinforcing member 30 have the same cross-sectional shapes as the first reinforcing member 20 and the second reinforcing member 30 illustrated in FIG. 15. The maximum dimension W2MAX in the width direction of the second reinforcing member 30 (maximum width dimension W2MAX) is larger than the width dimension W1 of the first reinforcing member 20.

[0083] 18 and 19, the first reinforcing member 20 and the second reinforcing member 30 are arranged with a gap between them in their width direction (mainly in the second direction X). Therefore, the first reinforcing member 20 and the second reinforcing member 30 do not overlap in the thickness direction Z of the diaphragm main body 10. The widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum dimension of either the first reinforcing member 20 or the second reinforcing member 30 in a cross section perpendicular to the longitudinal direction. Here, the widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is the distance between the centroid C1 of the first reinforcing member 20 and the centroid C2 of the second reinforcing member 30 in a cross section perpendicular to the longitudinal direction. The maximum dimension in the cross section of one reinforcing member may be, for example, the maximum dimension in the width direction (maximum width dimension) of one reinforcing member, or may be, for example, the maximum dimension in the height direction (maximum height dimension) of one reinforcing member.

[0084] In the diaphragm 1C shown in Fig. 18, the widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum width dimension W1MAX of the first reinforcing member 20. The symbol R in Fig. 18 indicates an example of a range three times the maximum width dimension W1MAX of the first reinforcing member 20, starting from the centroid C1 of the first reinforcing member 20. This indicates that Fig. 18 shows that the widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum width dimension W1MAX of the first reinforcing member 20.

[0085] In the diaphragm 1D shown in Fig. 19, the widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum width dimension W2MAX of the second reinforcing member 30. The symbol R in Fig. 19 indicates an example of a range three times the maximum width dimension W2MAX of the second reinforcing member 30, starting from the centroid C2 of the second reinforcing member 30. This indicates that Fig. 19 shows that the widthwise spacing I between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum width dimension W2MAX of the second reinforcing member 30.

[0086] As described above, in the diaphragms 1C and 1D of the second embodiment, similarly to the first embodiment, the first surface 10a of the diaphragm main body 10 is provided with an elongated first reinforcing member 20 that protrudes from the first surface 10a and extends in a direction (first direction Y) in which the diaphragm main body 10 is likely to deform (expand, contract, and / or bend). The second surface 10b of the diaphragm main body 10 is provided with an elongated second reinforcing member 30 that protrudes from the second surface 10b and extends in a direction in which the diaphragm main body 10 is likely to deform (expand, contract, contract, and / or bend). The first reinforcing member 20 and the second reinforcing member 30 are spaced apart in the width direction of the reinforcing members 20 and 30 when viewed from the thickness direction Z of the diaphragm main body 10. The widthwise spacing between the first reinforcing member 20 and the second reinforcing member 30 is three times or less the maximum dimension of a cross section of either the first or second reinforcing member 20 and 30 that is perpendicular to the longitudinal direction. As a result, as in the first embodiment, the first and second reinforcing members 20, 30 can effectively suppress the diaphragm main body 10 from expanding and contracting in a direction that makes it easier to expand and contract, or from bending in a direction that makes it easier to bend.

[0087] The diaphragms 1C and 1D of the second embodiment can achieve the same effects as those of the first embodiment described above. Furthermore, the musical instrument MI (see FIGS. 1 and 2) to which the diaphragms 1C and 1D of the second embodiment are applied achieves the same effects as those of the first embodiment.

[0088] The configuration of the reinforcing material in the second embodiment may be the same as, for example, the first embodiment (e.g., Figures 4 to 6) or its variants (e.g., Figures 8 to 17) described above, except that the first and second reinforcing materials 20, 30 are arranged spaced apart from each other in the width direction.

[0089] Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0090] In the present invention, the diaphragm main body 10 is not limited to a single plate material, and may be, for example, a plywood formed by stacking a plurality of plate materials 11 (three plates in the illustrated example) as shown in FIG. 20. In the diaphragm main body 10 illustrated in FIG. 20, the plate material 11 is a wooden plate 11. The plurality of wooden plates 11 each have a wood grain extending along the first surface 10a and the second surface 10b of the diaphragm main body 10. The wood grain directions of the plurality of wooden plates 11 may be aligned with each other, or may intersect with each other. For example, the wood grain direction of a predetermined wooden plate 11 may intersect with the wood grain directions of two other wooden plates 11 that sandwich the predetermined wooden plate 11, and the wood grain directions of the other two wooden plates 11 may be aligned with each other. A diaphragm main body 10 formed by stacking three plate materials 11 has anisotropy in bending deformation. Specifically, bending deformation is easier in the first direction Y than in the second direction X.

[0091] When the diaphragm main body 10 is made of the above-mentioned plywood, the first reinforcing member 20 provided on the first surface 10a and the second reinforcing member 30 provided on the second surface 10b preferably extend along the first surface 10a and the second surface 10b in a direction intersecting (e.g., perpendicular to) the grain direction of at least one wooden board 11. In other words, the first and second reinforcing members 20, 30 preferably extend in a direction in which at least one wooden board 11 is likely to expand and contract. In Fig. 20, the first and second reinforcing members 20, 30 extend in a direction perpendicular to the grain direction of the wooden board 11 that forms the first surface 10a of the diaphragm main body 10. Even if the diaphragm body 10 is made of plywood, by providing the first and second reinforcing members 20, 30 as described above, the first and second reinforcing members 20, 30 can effectively suppress the diaphragm body 10 from bending in a direction in which it is more susceptible to bending deformation (bending deformation of the diaphragm body 10), as in the first and second embodiments.

[0092] The diaphragm of the present invention is not limited to keyboard instruments such as the piano illustrated in FIGS. 1 and 2, but can also be applied to other instruments equipped with a diaphragm, such as string instruments and percussion instruments (for example, cajon). [Explanation of symbols]

[0093] 1, 1C, 1D... diaphragm, 2... vibrator, 10... diaphragm body, 10a... first surface, 10b... second surface, 11... wooden board (board material), 20... first reinforcing material, 30... second reinforcing material, X... second direction (wood grain direction), Y... first direction (direction in which diaphragm body 10 is easily deformed), Z... thickness direction

Claims

1. A plate-shaped diaphragm body that has anisotropic deformation; a first reinforcing member having an elongated shape and provided on a first surface of the diaphragm body so as to protrude from the first surface and extend along the first surface in a direction in which the diaphragm body is easily deformed; a second reinforcing member having an elongated shape and provided on a second surface of the diaphragm body so as to protrude from the second surface and extend along the second surface in a direction in which the diaphragm body is easily deformed; the first surface and the second surface face in opposite directions in a thickness direction of the diaphragm body, A diaphragm in which, when viewed from the thickness direction of the diaphragm body, at least a portion of the width direction of the first reinforcing material and the second reinforcing material overlaps with at least a portion of the length direction of the first reinforcing material and the second reinforcing material.

2. The diaphragm according to claim 1 , wherein at least a portion of the first reinforcing member and the second reinforcing member in the width direction overlaps over the entire length of at least one of the first reinforcing member and the second reinforcing member.

3. A plate-shaped diaphragm body that has anisotropic deformation; a first reinforcing member having an elongated shape and provided on a first surface of the diaphragm body so as to protrude from the first surface and extend along the first surface in a direction in which the diaphragm body is easily deformed; a second reinforcing member having an elongated shape and provided on a second surface of the diaphragm body so as to protrude from the second surface and extend along the second surface in a direction in which the diaphragm body is easily deformed; the first surface and the second surface face in opposite directions in a thickness direction of the diaphragm body, the first reinforcing member and the second reinforcing member are arranged at an interval in the width direction as viewed from the thickness direction of the diaphragm body, A diaphragm in which the widthwise distance between the first reinforcing material and the second reinforcing material is three times or less the maximum dimension of either the first reinforcing material or the second reinforcing material in a cross section perpendicular to its longitudinal direction.

4. the diaphragm body is made of wood having a grain extending along the first surface and the second surface, The diaphragm according to claim 1 , wherein the first reinforcing member and the second reinforcing member extend in a direction intersecting with a grain direction of the diaphragm body.

5. The diaphragm body is made of plywood laminated with a plurality of wooden boards, Each of the plurality of wooden boards has a grain extending along the first surface and the second surface, The diaphragm according to claim 1 , wherein the first reinforcing member and the second reinforcing member extend in a direction intersecting with a grain direction of at least one of the wooden boards.

6. The diaphragm according to claim 1 , wherein the first reinforcing member and the second reinforcing member have the same rigidity.

7. The diaphragm according to claim 1 , wherein the first reinforcing member and the second reinforcing member are made of the same material.

8. 8. The diaphragm according to claim 6, wherein a cross-sectional area of ​​the first reinforcing member perpendicular to the longitudinal direction and a cross-sectional area of ​​the second reinforcing member perpendicular to the longitudinal direction are equal to each other.

9. 9. The diaphragm according to claim 1, wherein the first reinforcing material and the second reinforcing material are arranged so as to be symmetrical with each other in the longitudinal direction of the first reinforcing material and the second reinforcing material.

10. A musical instrument comprising: the diaphragm according to claim 1; and a vibrator that vibrates the diaphragm body.

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