Board material, musical instrument, and stringed musical instrument

Abstract

To provide a board material capable of generating a moderately soft sound, even if the board material is made of a material other than a specific type of wood.SOLUTION: There is provided a board material 1, in which a first shear modulus in a plane including a thickness direction Z and a first direction Y orthogonal to the thickness direction Z is lower than a second shear modulus in a plane including the thickness direction Z and a second direction X orthogonal to the thickness direction Z and the first direction Y, and multiple voids 2 are arranged inside at intervals in a plane direction including the first direction Y and the second direction X.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a board, a musical instrument, and a stringed instrument. [Background technology]

[0002] 2. Description of the Related Art Musical instruments such as acoustic guitars and acoustic pianos include a plate that produces sound when vibrated (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,342,161 Summary of the Invention [Problem to be solved by the invention]

[0004] For the board materials used in musical instruments, etc., certain woods (such as spruce) that produce a moderately soft sound are sometimes used preferably. A soft sound is a sound in which the volume of higher-order vibrations (high-pitched sounds) is moderately suppressed. However, when a particular wood is expensive or difficult to obtain, it is difficult to obtain a board material that produces a moderately soft sound. For this reason, there is a demand for a board material that produces a moderately soft sound without being limited to a particular wood.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a board material that is capable of producing an appropriately soft sound even if the board material is made of a material other than a specific type of wood, and a musical instrument and a stringed instrument that are equipped with the same. [Means for solving the problem]

[0006] A first aspect of the present invention is a sheet material having a first shear modulus in a plane including a thickness direction and a first direction perpendicular to the thickness direction, which is lower than a second shear modulus in a plane including the thickness direction and a second direction perpendicular to the thickness direction and the first direction, and having a plurality of voids arranged at intervals within the sheet material in a planar direction including the first direction and the second direction.

[0007] A second aspect of the present invention is a musical instrument having the above-mentioned plate material.

[0008] A third aspect of the present invention is a stringed instrument comprising the above-mentioned board and strings, wherein the second direction of the board substantially coincides with a longitudinal direction of the strings. Effect of the Invention

[0009] According to the present invention, it is possible to provide a board material that is capable of producing a moderately soft sound even if the board material is made of a material other than a specific wood, as well as a musical instrument and a stringed instrument that include the same. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an example of a stringed instrument to which the plate material of the present invention is applied; [Diagram 2] FIG. 2 is a schematic diagram for explaining a first shear modulus and a second shear modulus in the plate material of the present invention. [Diagram 3] FIG. 2 is an exploded perspective view showing a main part of the plate material according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a plan view showing a main part of the plate material according to the first embodiment of the present invention, with one second layer cut away. [Diagram 5] 5 is a cross-sectional view taken along line VV in FIG. 4. [Figure 6] FIG. 4 is a cross-sectional view showing a modified example of the plate material according to the first embodiment of the present invention. [Figure 7] FIG. 4 is a plan view showing a main portion of a first layer of a plate material according to a second embodiment of the present invention. [Figure 8] FIG. 11 is a plan view showing a main portion of a first layer of a plate material according to a third embodiment of the present invention. [Figure 9] FIG. 11 is a perspective view showing a main portion of a first layer of a plate material according to a fourth embodiment of the present invention. [Figure 10] 10 is an enlarged cross-sectional view of the plate material of FIG. 9 cut in a direction perpendicular to the Z-axis direction. [Figure 11] FIG. 11 is a perspective view showing a first example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 12] FIG. 11 is a perspective view showing a second example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 13] FIG. 11 is a perspective view showing a third example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 14] FIG. 11 is a perspective view showing a fourth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 15] FIG. 11 is a perspective view showing a fifth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 16] FIG. 11 is a perspective view showing a sixth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 17] FIG. 11 is a perspective view showing a seventh example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 18] FIG. 13 is a perspective view showing an eighth example of a lattice structure unit constituting a plate material according to another embodiment of the present invention. [Figure 19] FIG. 13 is a perspective view showing a ninth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 20] FIG. 11 is a perspective view showing a tenth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Figure 21] FIG. 13 is a perspective view showing an eleventh example of a lattice structure unit constituting a plate material according to another embodiment of the present invention. [Figure 22] FIG. 23 is a perspective view showing a twelfth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. [Diagram 23]FIG. 23 is a perspective view showing a thirteenth example of a unit lattice structure constituting a plate material according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First, an example of a stringed instrument to which the plate material of the present invention is applied will be described with reference to Fig. 1. The stringed instrument 10 shown in Fig. 1 is an acoustic guitar, and includes a body 11, a neck 12, a head 13, and strings 14.

[0012] The body 11 is formed in a box shape with a cavity inside. The body 11 has a top plate 21, a back plate 22, and a side plate 23 which form a cavity. The top plate 21 and the back plate 22 are arranged with a gap between them in the thickness direction. The side plate 23 extends from the periphery of the back plate 22 to the periphery of the top plate 21. The top plate 21 is formed with a resonator hole 24 (sound hole) which penetrates in the thickness direction. The cavity of the body 11 is connected to the space outside the body 11 through the resonator hole 24. A tailpiece 27 for fastening first ends of the strings 14 in the longitudinal direction is provided on the outer surface of the top plate 21.

[0013] The neck 12 extends in a direction away from the body 11. The head 13 is provided at the tip of the neck 12 and winds around a second end side of the string 14 in the longitudinal direction. The string 14 is stretched across the body 11 and the neck 12. Specifically, a first end of the string 14 is fastened to a tailpiece 27 of the body 11, and a second end of the string 14 is wound around the head 13. In this way, the string 14 is stretched between the tailpiece 27 and the head 13.

[0014] A bridge 28 is provided between the strings 14 stretched on the outer surface of the top plate 21 and the outer surface of the top plate 21. As a result, in the stringed instrument 10, the vibration of the strings 14 is transmitted to the top plate 21 via the bridge 28, causing the top plate 21 to vibrate. Furthermore, the air inside (the cavity of) the body 11 resonates in response to the vibration of the top plate 21, and sound is radiated outside the body 11.

[0015] The plate material of the present invention is a plate material that generates sound as it vibrates, and may be applied, for example, to the top plate 21 of the above-mentioned stringed instrument 10. The plate material of the present invention may also be applied, for example, to the back plate 22 or side plate 23 of the stringed instrument 10.

[0016] In the plate material of the present invention, as shown in Fig. 2, a first shear modulus Gyz in a plane YZ including the plate thickness direction (Z-axis direction) and a first direction (Y-axis direction) perpendicular to the plate thickness direction is lower than a second shear modulus Gxz in a plane XZ including the plate thickness direction (Z-axis direction) and a second direction (X-axis direction) perpendicular to the plate thickness direction and the first direction. That is, the plate material of the present invention has anisotropy with respect to the shear modulus. When the "specific wood" targeted by the board material of the present invention is straight-grained spruce material, for example, the second shear modulus Gxz is preferably about 10 to 20 times the first shear modulus Gyz.

[0017] 1 and 3 to 10, the thickness direction, first direction, and second direction of the plate material of the present invention are shown as the Z-axis direction, the Y-axis direction, and the X-axis direction, respectively. Note that the X-axis direction, the Y-axis direction, and the Z-axis direction in Fig. 1 show an example of the directions when the plate material of the present invention is applied to the front plate 21 (or the back plate 22).

[0018] First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in Figs. 4 and 5, the plate material 1 of the first embodiment has a plurality of voids 2 therein. The plurality of voids 2 are arranged at intervals in the surface direction of the plate material 1, including the first direction and the second direction. In this embodiment, the plurality of voids 2 are uniformly distributed in the surface direction. In this embodiment, there is only one layer in the plate thickness direction that includes the plurality of voids 2 arranged in the surface direction of the plate material 1. Note that the layers including the plurality of voids 2 arranged in the surface direction may overlap each other in the plate thickness direction, for example.

[0019] The second dimension 2x of the gap 2 in the second direction is greater than the first dimension 2y of the gap 2 in the first direction. The comparison of the first dimension 2y and the second dimension 2x is for the same gap 2. That is, for the same gap 2, the second dimension 2x is greater than the first dimension 2y.

[0020] All the voids 2 in the plate material 1 have the same shape and size. The voids 2 in the first embodiment are formed in a symmetrical hexagon when viewed in the thickness direction of the plate material 1. Specifically, the voids 2 have a shape obtained by extending a regular hexagon in the second direction. In FIG. 4, a pair of parallel sides of the voids 2 that are hexagonal in plan view extend in the second direction. Note that a pair of parallel sides of the voids 2 that are hexagonal in plan view may extend in the first direction, for example. The shape and size of the void 2 as viewed in the plate thickness direction do not change in the plate thickness direction. Therefore, the three-dimensional shape of the void 2 is a hexagonal prism in which the second dimension 2x is larger than the first dimension 2y.

[0021] The plurality of voids 2, each of which is hexagonal in plan view, are arranged to form a honeycomb structure. The plurality of voids 2 are also arranged in the planar direction such that the thicknesses of the partition walls 3 that partition adjacent voids 2 in the planar direction are approximately uniform.

[0022] As shown in FIGS. 3 and 5, the plate material 1 of the first embodiment includes a first layer 4 and a second layer 5. The first layer 4 is a layer whose thickness direction is in the Z-axis direction, and includes a plurality of voids 2. The plurality of voids 2 each open to both sides of the first layer 4 in the thickness direction of the first layer 4. That is, each void 2 penetrates the first layer 4 in the thickness direction. The second layer 5 is a layer whose thickness direction is the Z-axis direction, similar to the first layer 4. The second layer 5 overlaps the first layer 4 in the thickness direction. In this embodiment, the second layer 5 overlaps both sides of the first layer 4. As a result, openings on both sides of the gap 2 in the first layer 4 are blocked by the second layer 5.

[0023] The second layer 5 has a higher strength than the first layer 4. The "strength" of the first layer 4 and the second layer 5 may mean, for example, "the degree to which the first layer 4 or the second layer 5 does not break even if it is deformed by an external force." In this embodiment, the tensile modulus of elasticity in the first direction (Y-axis direction) of the second layer 5 is lower than the tensile modulus of elasticity in the second direction (X-axis direction) of the second layer 5. That is, the second layer 5 has anisotropy with respect to the tensile modulus of elasticity.

[0024] In this embodiment, the second layer 5 does not have a void. The second layer 5 may have a void, for example. However, considering that the strength of the second layer 5 is higher than the strength of the first layer 4, the size of the void in the second layer 5 is preferably smaller than the void 2 in the first layer 4. Furthermore, in the void in the second layer 5, as in the case of the void 2 in the first layer 4, it is preferable that the second dimension is larger than the first dimension.

[0025] The substrate (material) constituting the board 1 may be any general-purpose resin, light metal, super engineering plastic, fiber-reinforced plastic (FRP), wood other than specific wood, etc. The substrate constituting the first layer 4 and the substrate constituting the second layer 5 may be the same as or different from each other.

[0026] The plate material 1 of the present embodiment may be manufactured, for example, by preparing the first layer 4 and the second layer 5, and then stacking the second layer 5 on the first layer 4. The first layer 4 and the second layer 5 may each be manufactured by, for example, a 3D printer.

[0027] In the stringed instrument 10 of FIG. 1 to which the plate material 1 of the present embodiment configured as described above is applied, the second direction (X-axis direction) of the plate material 1 is approximately aligned with the longitudinal direction of the strings 14. Here, "approximately aligned" includes that the second direction of the plate material 1 may be completely aligned with the longitudinal direction of the strings 14, but also includes that the second direction may be slightly inclined with respect to the longitudinal direction of the strings 14. Note that the upper limit of the inclination angle of the second direction of the plate material 1 with respect to the longitudinal direction of the strings 14 is preferably less than 45 degrees, for example, taking into consideration anisotropy in the parallel / perpendicular directions to the strings 14. On the other hand, the lower limit of the inclination angle may be, for example, 0 degrees, but is preferably 10 degrees or more to ensure strength when the plate material 1 is designed with a notch.

[0028] As described above, according to the first embodiment, the plate material 1 has a plurality of voids 2 arranged at intervals in the planar direction including the first direction and the second direction, so that it is possible to obtain a plate material 1 having a first shear modulus Gyz lower than the second shear modulus Gxz. Specifically, the second dimension 2x of each void 2 is larger than the first dimension 2y, so that it is possible to obtain a plate material 1 having a first shear modulus Gyz lower than the second shear modulus Gxz. And, because the board material 1 has the above-mentioned anisotropy in terms of the shear modulus, even a board material 1 made of a material other than specific wood (for example, a cheap or easily available board material 1) can generate a moderately soft sound similar to that of specific wood. A moderately soft sound is, for example, a sound in which the magnitude of higher-order vibrations (high-pitched sounds) is smaller than that of metal (for example, aluminum) and louder than that of foam material.

[0029] Moreover, in the plate material 1 of the first embodiment, the multiple voids 2 have the same shape and size. Therefore, compared to a case where the multiple voids 2 have different shapes and sizes, the number of parameters for adjusting the characteristics of the plate material 1 (for example, the ratio between the first dimension 2y and the second dimension 2x of each void 2) can be reduced. Therefore, it is easy to design a plate material 1 having a first shear modulus Gyz lower than the second shear modulus Gxz.

[0030] Moreover, the plate material 1 of the first embodiment includes a first layer 4 including a plurality of voids 2, and a second layer 5 overlapping the first layer 4 in the plate thickness direction and having a higher strength than the first layer 4. As a result, even if the first layer 4 has low strength due to the presence of the voids 2, the strength of the plate material 1 can be reinforced by the second layer 5.

[0031] In the board material 1 of the first embodiment, the tensile modulus in the first direction in the second layer 5 is lower than the tensile modulus in the second direction in the second layer 5. This allows the characteristics of low-order vibrations (low-frequency sounds) generated in the board material 1 to be closer to those of a specific wood material (for example, spruce wood).

[0032] Furthermore, in the plate material 1 of the first embodiment, the second layer 5 overlaps both sides of the first layer 4 in the plate thickness direction. This makes it possible to effectively suppress warping of the plate material 1.

[0033] Furthermore, in the plate material 1 of the first embodiment, the gap 2 penetrates the first layer 4 in the thickness direction. For this reason, if the plate material is composed only of the first layer 4, the sound pressure generated by the vibration of the plate material cannot be obtained sufficiently. In contrast, in the plate material 1 of the first embodiment, by overlapping the second layer 5 on both sides of the first layer 4, the openings on both sides of the gap 2 are blocked by the second layer 5. As a result, the sound pressure generated by the vibration of the plate material 1 can be obtained sufficiently.

[0034] Furthermore, in a stringed instrument 10 (musical instrument) having the board material 1 of the first embodiment, even if the stringed instrument 10 is constructed using a board material 1 made of a material other than a specific wood (for example, an inexpensive or easily available board material 1), it is possible to provide a stringed instrument 10 that produces a moderately soft sound.

[0035] In the stringed instrument 10 having the plate 1 of the first embodiment, the second direction of the plate 1 substantially coincides with the longitudinal direction of the strings 14 (i.e., the stringing direction). This makes it possible to effectively suppress or prevent the plate 1 from being deflected by the tension of the strings 14.

[0036] In the plate material of the first embodiment, the first layer 4 and the second layer 5 may be integrally formed, for example, as shown in Fig. 6. In this case, the first layer 4 and the second layer 5 may be manufactured at the same time by, for example, a 3D printer.

[0037] In the first embodiment, the multiple voids 2 included in the first layer 4 may be open, for example, on only one side of the first layer 4 in the thickness direction. In this case, the sound pressure generated by the vibration of the plate material 1 can be sufficiently obtained by simply covering the openings of the voids 2 by overlapping the second layer 5 on only one side of the first layer 4 where the voids 2 are open.

[0038] Furthermore, in the first embodiment, the multiple voids 2 contained in the first layer 4 do not have to be open on both sides of the first layer 4 in the thickness direction, for example. In this case, the second layer 5 may be overlaid on both sides of the first layer 4, or may be overlaid on only one side of the first layer 4. Furthermore, the plate material 1 does not have to include the second layer 5, that is, the plate material 1 may be composed of only the first layer 4.

[0039] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 7. In the following description, configurations common to those already described will be given the same reference numerals and duplicated description will be omitted.

[0040] The plate material of the second embodiment differs from the plate material 1 of the first embodiment only in the shape of the voids 2 in the first layer 4. Fig. 7 shows only the first layer 4 in a plan view of the plate material 1B of the second embodiment. 7, the planar shape of the void 2 as viewed from the plate thickness direction (Z-axis direction) is a rectangle with a second dimension 2x larger than a first dimension 2y. The shape and size of the void 2 as viewed from the plate thickness direction do not change in the plate thickness direction. Therefore, the three-dimensional shape of the void 2 is a rectangular parallelepiped with a second dimension 2x larger than a first dimension 2y. The shapes and sizes of the multiple voids 2 are equal to each other.

[0041] The plurality of voids 2, each rectangular in plan view, are arranged at intervals in the first and second directions to form a planar grid structure. The plurality of voids 2 are also arranged such that the thicknesses of partition walls 3 that partition adjacent voids 2 in the surface direction are approximately uniform. Specifically, the partition wall 3 includes a first partition wall 3-1 having a wall thickness direction in the first direction and a second partition wall 3-2 having a wall thickness direction in the second direction. The first partition wall 3-1 and the second partition wall 3-2 have the same thickness dimension.

[0042] According to the plate material 1B of the second embodiment, the same effects as those of the first embodiment are achieved.

[0043] <Third embodiment> Next, a third embodiment of the present invention will be described with reference to Fig. 8. In the following description, components common to those already described will be given the same reference numerals and duplicated description will be omitted.

[0044] The plate material of the third embodiment differs from the first and second embodiments in the shape of the gaps 2 in the first layer 4 and the aspect of the partition walls 3. Fig. 8 shows only the first layer 4 in a plan view of the plate material 1C of the third embodiment. As shown in Fig. 8, the planar shape of the void 2 as viewed from the plate thickness direction (Z-axis direction) is a square with the second dimension 2x and the first dimension 2y being equal. The shape and size of the void 2 as viewed from the plate thickness direction do not change in the plate thickness direction. Therefore, the three-dimensional shape of the void 2 is a rectangular parallelepiped or a cube. The shapes and sizes of the multiple voids 2 are equal to each other.

[0045] The multiple voids 2, each of which is a square in plan view, are arranged at intervals in the first direction and the second direction to form a planar lattice structure similar to the second embodiment. The multiple voids 2 are also arranged such that the intervals between the voids 2 in the first direction are larger than the intervals between the voids 2 in the second direction. Specifically, the partition walls 3 that partition adjacent voids 2 in a surface direction including the first direction and the second direction include a first partition wall 3-1 whose wall thickness direction is the first direction and a second partition wall 3-2 whose wall thickness direction is the second direction. The thickness dimension 3Ty of the first partition wall 3-1 is larger than the thickness dimension 3Tx of the second partition wall 3-2. The thickness dimension 3Ty of the first partition wall 3-1 corresponds to the distance between the voids 2 in the first direction. The thickness dimension 3Tx of the second partition wall 3-2 corresponds to the distance between the voids 2 in the second direction.

[0046] The plate material 1C of the third embodiment provides the same effects as those of the first embodiment. In addition, in the plate material 1C of the third embodiment, the thickness dimension 3Ty of the first partition wall 3-1 is larger than the thickness dimension 3Tx of the second partition wall 3-2. Therefore, the shear modulus of the second partition wall 3-2 is lower than the shear modulus of the first partition wall 3-1, and the rigidity of the first partition wall 3-1 is higher than the rigidity of the second partition wall 3-2. The shear modulus of the second partition wall 3-2 corresponds to the first shear modulus Gyz (see FIG. 2), and the shear modulus of the first partition wall 3-1 corresponds to the second shear modulus Gxz (see FIG. 2). Therefore, even if the first dimension 2y and the second dimension 2x of the same gap 2 are equal, a plate material 1C can be configured in which the first shear modulus Gyz is lower than the second shear modulus Gxz.

[0047] The configuration of the third embodiment, i.e., the configuration in which the thickness dimension 3Ty of the first partition wall 3-1 is larger than the thickness dimension 3Tx of the second partition wall 3-2 and the shear modulus of the second partition wall 3-2 is lower than the shear modulus of the first partition wall 3-1, can also be applied to a plate material in which the planar shape of the gap 2 is hexagonal as in the first embodiment.

[0048] The first partition wall 3-1 may be a partition wall 3 whose wall thickness direction is mainly oriented in the first direction, and may include, for example, a partition wall 3 whose wall thickness direction is inclined at an angle of 45 degrees or less with respect to the first direction. On the other hand, the second partition wall 3-2 may be a partition wall 3 whose wall thickness direction is mainly oriented in the second direction, and may include, for example, a partition wall 3 whose wall thickness direction is inclined at an angle of 45 degrees or less with respect to the second direction. Also, for example, a first partition wall 3-1 whose wall thickness direction is mainly oriented in a first direction may be a portion of the partition wall 3 that is orthogonally projected in the first direction, and a second partition wall 3-2 whose wall thickness direction is mainly oriented in a second direction may be a portion of the partition wall 3 that is orthogonally projected in the second direction.

[0049] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described with reference to Figures 9 and 10. In the following description, components common to those already described will be given the same reference numerals and duplicated description will be omitted.

[0050] The plate material of the fourth embodiment differs from that of the third embodiment in the aspect of the partition wall 3. Fig. 9 and Fig. 10 show only the first layer 4 of a plate material 1D of the fourth embodiment. As shown in Fig. 10, the planar shape of the void 2 as viewed from the plate thickness direction (Z-axis direction) is a square with the second dimension 2x and the first dimension 2y being equal, as in the third embodiment. Also, as shown in Figs. 9 and 10, the shape and size of the void 2 as viewed from the plate thickness direction do not change in the plate thickness direction. Therefore, the three-dimensional shape of the void 2 is a rectangular parallelepiped or cube. The shapes and sizes of the multiple voids 2 are equal to each other.

[0051] The plurality of voids 2, each of which is a square in plan view, are arranged at intervals in the first and second directions to form a planar lattice structure, as in the third embodiment. However, the plurality of voids 2 are arranged such that the intervals between the voids 2 in the first direction are equal to the intervals between the voids 2 in the second direction. Specifically, the partition walls 3 that partition adjacent voids 2 in a surface direction including the first and second directions include a first partition wall 3-1 whose wall thickness direction is the first direction and a second partition wall 3-2 whose wall thickness direction is the second direction. The thickness dimension of the first partition wall 3-1 is equal to the thickness dimension of the second partition wall 3-2.

[0052] In the first layer 4 of the fourth embodiment, a plurality of through holes 7 (7-1, 7-2) connecting adjacent gaps 2 are formed in the partition wall 3. In the entire first layer 4 (plate material 1D), the sum of the first areas of the through holes 7 projected in the first direction is smaller than the sum of the second areas of the through holes 7 projected in the second direction.

[0053] Specifically, in the plate material 1D illustrated in Figs. 9 and 10, the multiple through holes 7 include a first through hole 7-1 and a second through hole 7-2. The first through hole 7-1 penetrates the first partition wall 3-1 in a first direction. Therefore, the area 7Sy of the first through hole 7-1 as viewed from the penetration direction is entirely included in the first area. On the other hand, the second through hole 7-2 penetrates the second partition wall 3-2 in a second direction. Therefore, the area 7Sx of the second through hole 7-2 as viewed from the penetration direction is entirely included in the second area.

[0054] The area 7Sy (first area) of the first through hole 7-1 viewed from the first direction is smaller than the area 7Sx (second area) of the second through hole 7-2 viewed from the second direction. The areas 7Sy (first areas) of the multiple first through holes 7-1 are equal to each other. The areas 7Sx (second areas) of the multiple second through holes 7-2 are equal to each other. Therefore, in the entire first layer 4 (plate material 1D), the sum of the areas 7Sy (first area) of the multiple first through holes 7-1 is smaller than the sum of the areas 7Sx (second area) of the multiple second through holes 7-2.

[0055] According to the plate material 1D of the fourth embodiment, the same effects as those of the first embodiment are achieved. In the plate material 1D of the fourth embodiment, a plurality of through holes 7 connecting adjacent voids 2 are formed in the partition wall 3. The sum of the first areas of the through holes 7 projected in the first direction is smaller than the sum of the second areas of the through holes 7 projected in the second direction. This makes it possible to configure a plate material 1D in which the first shear modulus Gyz is lower than the second shear modulus Gxz even if the first dimension 2y and the second dimension 2x of the same void 2 are equal, and even if the thickness dimension of the first partition wall 3-1 and the thickness dimension of the second partition wall 3-2 are equal.

[0056] For example, in the first layer 4 (plate material 1D) illustrated in FIG. 10, the area 7Sy (first area) of the first through hole 7-1 formed in the first partition wall 3-1 is smaller than the area 7Sx (second area) of the second through hole 7-2 formed in the second partition wall 3-2. Therefore, the shear modulus of the first partition wall 3-1 is higher than the shear modulus of the second partition wall 3-2, and the rigidity of the first partition wall 3-1 is higher than the rigidity of the second partition wall 3-2. The shear modulus of the second partition wall 3-2 corresponds to the first shear modulus of elasticity Gyz (see FIG. 2), and the shear modulus of the first partition wall 3-1 corresponds to the second shear modulus of elasticity Gxz (see FIG. 2). Therefore, even if the first dimension 2y and the second dimension 2x of the same gap 2 are equal, and even if the thickness dimension of the first partition wall 3-1 and the thickness dimension of the second partition wall 3-2 are equal, a plate material 1D can be configured in which the first shear modulus of elasticity Gyz is lower than the second shear modulus of elasticity Gxz.

[0057] The configuration of the fourth embodiment, i.e., a configuration in which a plurality of through holes 7 connecting adjacent gaps 2 are formed in the partition wall 3 and the sum of the first areas of the through holes 7 projected in a first direction is smaller than the sum of the second areas of the through holes 7 projected in a second direction, can also be applied to a plate material in which the planar shape of the gap 2 is hexagonal as in the first embodiment.

[0058] In the fourth embodiment, for example, the planar shape of the first through hole 7-1 seen from the first direction and the planar shape of the second through hole 7-2 seen from the second direction may be different, so that the shear modulus of the second partition wall 3-2 may be lower than the shear modulus of the first partition wall 3-1. In this case, by making the planar shape of the first through hole 7-1 and the planar shape of the second through hole 7-2 different, even if the first dimension and the second dimension of the same gap 2 are equal and even if the area of ​​the first through hole 7-1 seen from the first direction and the area of ​​the second through hole 7-2 seen from the second direction are equal, a plate member can be configured in which the shear modulus of the first partition wall 3-1 is lower than the shear modulus of the second partition wall 3-2.

[0059] The first and second through holes 7-1, 7-2 have different planar shapes, which means that even if the areas of the figures (planar figures) of the first and second through holes 7-1, 7-2 in plan view are the same, the shapes of the planar figures of the first and second through holes 7-1, 7-2 themselves are different from each other. For example, the planar figure of the first through hole 7-1 may be rectangular, and the planar figure of the second through hole 7-2 may be circular. In this case, the shear modulus of elasticity of the second partition wall 3-2 can be made lower than the shear modulus of elasticity of the first partition wall 3-1.

[0060] In addition, the planar shapes of the first and second through holes 7-1 and 7-2 may be different from each other, for example, the planar shapes of the first and second through holes 7-1 and 7-2 may be the same planar shapes that are not point symmetric, and the rotational positions of the planar shapes are different between the first through hole 7-1 and the second through hole 7-2, so that the planar shapes of the first and second through holes 7-1 and 7-2 are different from each other. Examples of the planar shapes of the first and second through holes 7-1 and 7-2 that are not point symmetric include polygons such as triangles and rectangles, and ellipses. For example, the planar shapes of the first and second through holes 7-1 and 7-2 may both be squares, and the planar shapes of the first and second through holes 7-1 and 7-2 may be shifted from each other by rotating 45 degrees.

[0061] When the first and second through holes 7-1, 7-2 are squares with the same area in plan view, for example, each side of the first through hole 7-1, which is square in plan view and formed in the first partition wall 3-1, may be inclined (for example, inclined by 45 degrees) with respect to the plate thickness direction (Z-axis direction) and the second direction (X-axis direction) of the plate material, and each side of the second through hole 7-2, which is square in plan view and formed in the second partition wall 3-2, may be aligned with the plate thickness direction (Z-axis direction) and the second direction (X-axis direction) of the plate material. This makes the shear modulus of elasticity of the second partition wall 3-2 lower than that of the first partition wall 3-1.

[0062] Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0063] In the plate material of the present invention, the gaps 2 may be filled with a filler such as a foam material. In this case, the density of the filler may be smaller than the density of the first layer 4. In addition, the filler may be lighter than the second layer 5.

[0064] In the plate material of the present invention, the shape of the voids 2 may be any shape. For example, the planar shape of the voids 2 as viewed in the thickness direction or the first or second direction of the plate material 1 is not limited to a hexagon or rectangle, and may be other polygonal, circular, elliptical, etc. Furthermore, the three-dimensional shape of the voids 2 may be any shape, such as a cylinder, ellipsoid, hexahedron, or octahedron.

[0065] The "honeycomb structure" in the present invention is not limited to a structure in which a plurality of voids 2 are arranged in a hexagonal shape when viewed from above, as in the first embodiment, but may also include a structure in which the voids 2 are formed in any polygonal shape when viewed from above, the sides of adjacent voids 2 are parallel to each other, and the distance between adjacent voids 2 is small.

[0066] In the plate material of the present invention, the voids 2 may have a variety of shapes and sizes. That is, a single plate material may contain a variety of voids 2 with different shapes and sizes. In this case, the characteristics of the plate material can be adjusted with higher accuracy.

[0067] In the present invention, the specific structure for arranging multiple voids 2 inside the plate material is not limited to the honeycomb structure or planar grid structure as in the above embodiments, but may be, for example, a lattice structure, expanded metal, mesh sheet, woven structure, etc.

[0068] An example of a single unit of lattice structure is shown in Figures 11 to 23. A plate material of the present invention employing a lattice structure can be constructed by arranging a plurality of single unit lattice structures shown in each of Figures 11 to 23 at least in the first direction and the second direction. Each of the lattice structures of one unit shown in Figures 11 to 23 is formed by appropriately connecting a plurality of beams 8. For example, in the lattice structure of Figure 12, the plurality of beams 8 include an outer beam 81 that forms the outer frame of the lattice structure, and an inner beam 82 that extends inside the outer frame.

[0069] In the lattice structures shown in Figs. 11 to 23, the three-dimensional shape of the smallest unit formed by several beams 8 corresponds to the void 2 in the present invention. For example, in the lattice structure in Fig. 12, a quadrangular pyramid is formed by four outer beams 81 forming a square and four inner beams 82 extending from each corner formed by the four outer beams 81 to the center of the cube. The space inside this quadrangular pyramid corresponds to the void 2 in the present invention. In the lattice structure in Fig. 12, there are six quadrangular pyramids that form the void 2.

[0070] 11 to 23, the planar shape of the smallest unit formed by several beams 8 corresponds to the partition wall of the present invention. For example, in the lattice structure of Fig. 12, a square portion formed by four outer beams 81 and a triangular portion formed by one outer beam 81 and two inner beams 82 extending from both ends of the outer beam 81 each correspond to the partition wall of the present invention.

[0071] 11 to 23, a portion surrounded by several beams 8 constituting a minimum unit planar shape corresponds to the through hole 7 of the present invention. For example, in the lattice structure of Fig. 12, an inner portion of a square formed by four outer beams 81, and an inner portion of a triangle formed by one outer beam 81 and two inner beams 82 extending from both ends of the outer beam 81 each correspond to the through hole 7 of the present invention.

[0072] In the present invention, the properties of the sheet material, such as the shear modulus, flexural modulus, tensile modulus, etc., may be uniform throughout the sheet material, but may also vary, for example, in different regions of the sheet material.

[0073] In the plate material of the present invention, the plurality of voids 2 may be distributed non-uniformly, for example, in the surface direction. For example, in a portion of the plate material where strength needs to be ensured, the number of voids 2 per unit area may be reduced or the voids 2 may be made smaller, as compared with other portions of the plate material. In this case, for example, the characteristics of the plate material can be made different for each region of the plate material, as described above.

[0074] The plate material of the present invention may be applied not only to the stringed instrument 10 (acoustic guitar) illustrated in Fig. 1 but also to various instruments that use plate materials that generate sounds when vibrated, such as other stringed instruments such as electric guitars and violins, pianos, percussion instruments, etc. In other words, the plate material of the present invention may be a plate material for musical instruments.

[0075] Furthermore, the plate material of the present invention is not limited to being applied to musical instruments, but may also be applied to, for example, audio equipment such as speakers. In this case, the plate material of the present invention may be applied to, for example, the diaphragm or housing of the speaker. [Explanation of symbols]

[0076] 1, 1B, 1C, 1D...plate material, 2...gap, 2x...second dimension, 2y...first dimension, 3...compartment wall, 3-1...first compartment wall, 3-2...second compartment wall, 3Tx...thickness dimension of second compartment wall 3-2, 3Ty...thickness dimension of first compartment wall 3-1, 4...first layer, 5...second layer, 7...through hole, 7-1...first through hole, 7-2...second through hole, 7Sx...area of ​​second through hole 7-2 (second area), 7Sy...area of ​​first through hole 7-1 (first area), 10...stringed instrument, 14...string, Gxz...second shear modulus, Gyz...first shear modulus

Claims

1. A first shear modulus in a plane including a plate thickness direction and a first direction perpendicular to the plate thickness direction is lower than a second shear modulus in a plane including the plate thickness direction and a second direction perpendicular to the plate thickness direction and the first direction; A plate material having a plurality of voids arranged at intervals therein in a planar direction including the first direction and the second direction.

2. 2. The sheet of claim 1, wherein a second dimension of the gap in the second direction is greater than a first dimension of the gap in the first direction.

3. a partition wall that partitions the gaps adjacent to each other in the surface direction, The partition walls include a first partition wall having a wall thickness direction in the first direction and a second partition wall having a wall thickness direction in the second direction, The plate material according to claim 1 or 2, wherein the second partition wall has a lower shear modulus than the first partition wall.

4. a partition wall that partitions the gaps adjacent to each other in the surface direction, The partition walls include a first partition wall having a wall thickness direction in the first direction and a second partition wall having a wall thickness direction in the second direction, 3. The plate material according to claim 1, wherein a thickness dimension of the first partition wall is greater than a thickness dimension of the second partition wall.

5. a partition wall that partitions the gaps adjacent to each other in the surface direction, A plurality of through holes are formed in the partition wall to connect adjacent ones of the gaps, 3. The plate material according to claim 1 or claim 2, wherein a sum of first areas of the through holes projected in the first direction is smaller than a sum of second areas of the through holes projected in the second direction.

6. a partition wall that partitions the gaps adjacent to each other in the surface direction, A plurality of through holes are formed in the partition wall to connect adjacent ones of the gaps, The partition walls include a first partition wall having a wall thickness direction in the first direction and a second partition wall having a wall thickness direction in the second direction, The through holes include a first through hole formed in the first partition wall and a second through hole formed in the second partition wall, A plate material as described in claim 1 or claim 2, wherein the planar shape of the first through hole when viewed from the first direction is different from the planar shape of the second through hole when viewed from the second direction, such that the shear modulus of the second partition wall is lower than the shear modulus of the first partition wall.

7. 3. The plate material according to claim 1, comprising: a first layer including a plurality of the voids; and a second layer overlapping the first layer in the plate thickness direction and having a strength higher than that of the first layer.

8. The plate material according to claim 7 , wherein the second layer has a tensile modulus in the first direction that is lower than the tensile modulus in the second direction of the first layer.

9. The plate material according to claim 7 , wherein the second layer overlaps both sides of the first layer in the plate thickness direction.

10. A musical instrument comprising the plate material according to claim 1 or 2.

11. The board material according to claim 1 or 2 and a string, A stringed instrument, wherein the second direction of the plate material substantially coincides with the longitudinal direction of the strings.

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