Plate material, musical instrument, and stringed instrument

Abstract

Provided is a plate material 1 in which a first shear modulus in a plane including a plate thickness direction Z and a first direction Y orthogonal to a plate thickness direction Z is lower than a second shear modulus in a plane including the plate thickness direction Z and a second direction X orthogonal to the plate direction Z and the first direction Y, and which has, in the inside thereof, a plurality of voids 2 arranged at intervals in a plane direction including the first direction Y and the second direction X.

Description

Wood, musical instruments and string instruments

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

[0002] 2. Description of the Related Art Musical instruments such as acoustic guitars and acoustic pianos include plates that vibrate to produce sound (see, for example, Patent Document 1).

[0003] U.S. Patent No. 7,342,161

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

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a board material that can produce a moderately soft sound even if it is made of a material other than specific wood, as well as a musical instrument and a stringed instrument that include the same.

[0006] A first aspect of the present invention is a plate material having a first shear modulus in a plane including a thickness direction and a first direction perpendicular to the thickness direction that 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 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 having the plate and strings, wherein the second direction of the plate substantially coincides with the longitudinal direction of the strings.

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

[0010] 1 is a perspective view showing an example of a stringed instrument to which the plate material of the present invention is applied; FIG. 2 is a schematic view illustrating the first shear modulus and the second shear modulus in the plate material of the present invention; FIG. 3 is an exploded perspective view showing a main portion of the plate material according to the first embodiment of the present invention; FIG. 4 is a plan view showing a main portion of the plate material according to the first embodiment of the present invention, with one second layer cut away; FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4; FIG. 6 is a cross-sectional view showing a modified version of the plate material according to the first embodiment of the present invention; FIG. 7 is a plan view showing a main portion of the first layer of the plate material according to the second embodiment of the present invention; FIG. 8 is a plan view showing a main portion of the first layer of the plate material according to the third embodiment of the present invention; FIG. 9 is a perspective view showing a main portion of the first layer of the plate material according to the fourth embodiment of the present invention; FIG. 9 is an enlarged cross-sectional view taken in a direction perpendicular to the Z-axis direction of the plate material of FIG. 10; FIG. 11 is a perspective view showing a first example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention; FIG. 12 is a perspective view showing a second example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention; FIG. 13 is a perspective view showing a third example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention; FIG. 14 is a perspective view showing a fourth example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention; FIG. 15 is a perspective view showing a fifth example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention. FIG. 10 is a perspective view showing a sixth example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention. FIG. 11 is a perspective view showing a sixth example of a lattice structure of one unit constituting a plate material according to another embodiment of the present invention. FIG. 12 is a perspective view showing a lattice structure of one unit constituting a plate material according to another embodiment of the present invention. FIG. 13 is a perspective view showing a lattice structure of one unit constituting a plate material according to another embodiment of the present invention.

[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-like shape with an internal cavity. The body 11 has a top plate 21, a back plate 22, and side plates 23 that form the cavity. The top plate 21 and the back plate 22 are spaced apart in the thickness direction. The side plates 23 extend 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) that penetrates through it 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 is provided on the outer surface of the top plate 21, and fastens first longitudinal ends of the strings 14.

[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 a second end 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 vibrations of the strings 14 are transmitted to the top plate 21 via the bridge 28, causing the top plate 21 to vibrate. Furthermore, the air inside (cavity of) the body 11 resonates in response to the vibrations 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 Figure 2, the 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 the 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. In other words, the plate material of the present invention has anisotropy with respect to the shear modulus. When the "specific wood" targeted by the plate material of the present invention is straight-grained spruce, for example, it is preferable that the second shear modulus Gxz be 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 indicated by 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 indicate an example of directions when the plate material of the present invention is applied to the front plate 21 (or the back plate 22).

[0018] <First Embodiment> A first embodiment of the present invention will be described below with reference to Figures 3 to 5. As shown in Figures 4 and 5, a plate material 1 of the first embodiment has a plurality of voids 2 therein. These voids 2 are arranged at intervals in the surface direction of the plate material 1, which includes 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 a plurality of voids 2 arranged in the surface direction of the plate material 1. Note that multiple layers including a plurality of voids 2 arranged in the surface direction may overlap in the plate thickness direction, for example.

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

[0020] All voids 2 in the plate 1 have the same shape and size. In the first embodiment, the voids 2 are formed into symmetrical hexagons when viewed in the thickness direction of the plate 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 voids 2 when viewed in the thickness direction do not change in the thickness direction. Therefore, the three-dimensional shape of the voids 2 is a hexagonal prism in which the second dimension 2x is greater than the first dimension 2y.

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

[0022] As shown in Figures 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 on both sides of the first layer 4 in the thickness direction of the first layer 4. In other words, each void 2 penetrates the first layer 4 in the thickness direction. The second layer 5, like the first layer 4, is a layer whose thickness direction is in the Z-axis direction. 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, the openings on both sides of the voids 2 in the first layer 4 are blocked by the second layer 5.

[0023] The strength of the second layer 5 is higher than the strength of 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 when 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. In other words, the second layer 5 is anisotropic with respect to the tensile modulus of elasticity.

[0024] In this embodiment, the second layer 5 does not have a void. However, 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, it is preferable that the size of the void in the second layer 5 is smaller than the void 2 in the first layer 4. Furthermore, as with the void 2 in the first layer 4, it is preferable that the second dimension of the void in the second layer 5 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 this 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 using a 3D printer, for example.

[0027] In the stringed instrument 10 of Fig. 1 using the plate 1 of this embodiment configured as described above, the second direction (X-axis direction) of the plate 1 substantially coincides with the longitudinal direction of the strings 14. Here, "substantially coincides" means that the second direction of the plate 1 may completely coincide with the longitudinal direction of the strings 14, but also includes the possibility of the second direction being 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 1 with respect to the longitudinal direction of the strings 14 is preferably less than 45 degrees, for example, in consideration of anisotropy in the directions parallel and perpendicular 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 1 is designed with notches.

[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 and second directions. This makes it 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, thereby making it possible to obtain a plate material 1 having a first shear modulus Gyz lower than the second shear modulus Gxz. Furthermore, because the plate material 1 has the above-described anisotropy with respect to the shear modulus, even a plate material 1 made of a material other than specific wood (e.g., an inexpensive or easily available plate 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-frequency sounds) is smaller than that of metal (e.g., aluminum) and louder than that of foam.

[0029] Furthermore, in the plate material 1 of the first embodiment, the shapes and sizes of the plurality of voids 2 are the same. Therefore, compared to when the shapes and sizes of the plurality of voids 2 are different from one another, 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 in which the first shear modulus Gyz is lower than the second shear modulus Gxz.

[0030] The plate material 1 of the first embodiment includes a first layer 4 including a plurality of voids 2, and a second layer 5 that overlaps the first layer 4 in the plate thickness direction and has a strength higher than that of 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] Furthermore, in the board 1 of the first embodiment, the tensile modulus of elasticity in the first direction in the second layer 5 is lower than the tensile modulus of elasticity in the second direction in the second layer 5. This allows the characteristics of low-order vibrations (low-frequency sounds) generated in the board 1 to be closer to those of a specific wood material (for example, spruce).

[0032] 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 through the first layer 4 in the thickness direction. Therefore, 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 closed by the second layer 5. This makes it possible to obtain a sufficient sound pressure generated by the vibration of the plate material 1.

[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 board material 1 made of a material other than 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] Furthermore, 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), which effectively suppresses or prevents the plate 1 from being bent 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 collectively using a 3D printer, for example.

[0037] In the first embodiment, the plurality of voids 2 contained in the first layer 4 may each be open, for example, on only one side in the thickness direction of the first layer 4. In this case, simply by overlapping the second layer 5 on only one side of the first layer 4 where the voids 2 are open, thereby closing the openings of the voids 2, it is possible to obtain a sufficient sound pressure generated by the vibration of the plate material 1.

[0038] Furthermore, in the first embodiment, the plurality of voids 2 contained in the first layer 4 may not be open to 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 may not include the second layer 5, i.e., 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, components common to those already described will be assigned the same reference numerals and redundant 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 of the plate material 1B of the second embodiment in a plan view. As shown in FIG. 7, the planar shape of the voids 2 as viewed from the plate thickness direction (Z-axis direction) is a rectangle in which the second dimension 2x is larger than the first dimension 2y. Furthermore, the shape and size of the voids 2 as viewed from the plate thickness direction do not change in the plate thickness direction. Therefore, the three-dimensional shape of the voids 2 is a rectangular parallelepiped in which the second dimension 2x is larger than the first dimension 2y. The shapes and sizes of the multiple voids 2 are the same.

[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 so that the thicknesses of the partition walls 3 that separate adjacent voids 2 in the surface direction are generally uniform. Specifically, the partition walls 3 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 thicknesses of the first partition wall 3-1 and the second partition wall 3-2 are the same.

[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 assigned the same reference numerals and redundant description will be omitted.

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

[0045] The plurality of voids 2, each having a square shape in plan view, are arranged at intervals in the first and second directions to form a planar lattice structure, as in the second embodiment. The plurality of voids 2 are also arranged so that the spacing between the voids 2 in the first direction is greater than the spacing between the voids 2 in the second direction. Specifically, the partition walls 3 that separate 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 3Ty of the first partition wall 3-1 is greater 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 spacing between the voids 2 in the first direction. The thickness dimension 3Tx of the second partition wall 3-2 corresponds to the spacing between the voids 2 in the second direction.

[0046] The plate material 1C of the third embodiment achieves the same effects as the first embodiment. Furthermore, 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 void 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 plate materials 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. Furthermore, for example, the first partition wall 3-1 whose wall thickness direction is mainly oriented in the first direction may be a portion of the partition wall 3 that is orthogonally projected in the first direction, and the second partition wall 3-2 whose wall thickness direction is inclined in the 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 assigned the same reference numerals and redundant description will be omitted.

[0050] The plate material of the fourth embodiment differs from the third embodiment in the configuration of the partition wall 3. Figures 9 and 10 show only the first layer 4 of the plate material 1D of the fourth embodiment. As shown in Figure 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 equal, as in the third embodiment. Also, as shown in Figures 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 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 so 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 separate 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 Figures 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 as viewed from the first direction is smaller than the area 7Sx (second area) of the second through hole 7-2 as 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] The plate material 1D of the fourth embodiment achieves the same effects as the first embodiment. Furthermore, in the plate material 1D of the fourth embodiment, a plurality of through holes 7 connecting adjacent voids 2 are formed in the partition walls 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 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, 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 Gyz is lower than the second shear modulus Gxz.

[0057] The configuration of the fourth embodiment, i.e., a configuration in which multiple 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 plate materials in which the planar shape of the gaps 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 as viewed from the first direction may be different from the planar shape of the second through hole 7-2 as viewed from the second direction, 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 different from the planar shape of the second through hole 7-2, it is possible to configure a plate member 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, even if the first dimension and the second dimension of the same gap 2 are equal and the area of ​​the first through hole 7-1 as viewed from the first direction is equal to the area of ​​the second through hole 7-2 as viewed from the second direction.

[0059] The different planar shapes of the first and second through holes 7-1 and 7-2 mean that, for example, even if the areas of the shapes (planar shapes) of the first and second through holes 7-1 and 7-2 in plan view are the same, the shapes of the shapes themselves in plan view of the first and second through holes 7-1 and 7-2 are different from each other. For example, the shape of the first through hole 7-1 in plan view may be rectangular, and the shape of the second through hole 7-2 in plan view 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] Furthermore, the fact that the first and second through holes 7-1 and 7-2 have different planar shapes may mean, for example, that the planar shapes of the first and second through holes 7-1 and 7-2 are the same figure in plan view that is 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, resulting in different planar shapes of the first and second through holes 7-1 and 7-2. Examples of 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 by 45 degrees from each other.

[0061] When the first and second through holes 7-1, 7-2 have square shapes 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, at 45 degrees) with respect to the 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 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 embodiments, 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 lower 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 when viewed in the thickness direction of the plate material 1 or the first or second direction is not limited to a hexagon or rectangle, and may be other polygons, circles, ellipses, etc. Furthermore, the three-dimensional shape of the voids 2 may be any shape, such as a cylinder, an ellipsoid, a hexahedron, or an 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 in a planar view, as in the first embodiment, but may also include a structure in which the voids 2 are formed in any polygonal shape in a planar view, and the plurality of voids 2 are arranged so that 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, there may be a plurality of types of shapes and sizes of voids 2. That is, a single plate material may contain a plurality of types of voids 2 with different shapes and sizes. In this case, the characteristics of the plate material can be adjusted with higher precision.

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

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

[0069] In the lattice structures shown in Figures 11 to 23, the smallest unit three-dimensional shape formed by several beams 8 corresponds to the void 2 in the present invention. For example, in the lattice structure of Figure 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 of Figure 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, the square portion formed by four outer beams 81 and the 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, the portion surrounded by several beams 8 constituting the smallest unit planar shape corresponds to the through hole 7 of the present invention. For example, in the lattice structure of Fig. 12, the inner portion of a square formed by four outer beams 81 and the 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 plate, such as the shear modulus, flexural modulus, and tensile modulus, may be uniform throughout the plate, or may vary, for example, between different regions of the plate.

[0073] In the plate material of the present invention, the plurality of voids 2 may be distributed unevenly in the surface direction, for example. 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 compared to other portions of the plate material. In this case, for example, as described above, the characteristics of the plate material can be made different depending on the region of the plate material.

[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 other stringed instruments such as electric guitars and violins, as well as pianos and percussion instruments, which use plate materials that generate sound as they vibrate. 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, acoustic 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.

[0076] 1, 1B, 1C, 1D...plate material, 2...gap, 2x...second dimension, 2y...first dimension, 3...compartment wall, 3-1...first partition wall, 3-2...second partition wall, 3Tx...thickness dimension of second partition wall 3-2, 3Ty...thickness dimension of first partition 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 sheet material having a first shear modulus in a plane including a thickness direction and a first direction perpendicular to the thickness direction that 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 in the planar direction including the first direction and the second direction.

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

3. A plate material as described in claim 1 or claim 2, including partition walls that partition adjacent gaps in the surface direction, the partition walls including a first partition wall whose wall thickness direction is the first direction and a second partition wall whose wall thickness direction is the second direction, the shear modulus of elasticity of the second partition wall being lower than the shear modulus of elasticity of the first partition wall.

4. A sheet material as described in claim 1 or claim 2, including partition walls that partition adjacent gaps in the surface direction, the partition walls including a first partition wall whose wall thickness direction is the first direction and a second partition wall whose wall thickness direction is the second direction, and the thickness dimension of the first partition wall is greater than the thickness dimension of the second partition wall.

5. A sheet material as described in claim 1 or claim 2, comprising partition walls that separate adjacent voids in the surface direction, wherein the partition walls have a plurality of through holes that connect adjacent voids, and 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 plate material as described in claim 1 or claim 2, including partition walls that partition adjacent voids in the surface direction, wherein the partition walls have a plurality of through holes formed therein that connect adjacent voids, wherein the partition walls include a first partition wall whose wall thickness direction is the first direction and a second partition wall whose wall thickness direction is the second direction, wherein 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, wherein a planar shape of the first through hole as viewed from the first direction differs from a planar shape of the second through hole as viewed from the second direction, such that the shear modulus of elasticity of the second partition wall is lower than the shear modulus of elasticity of the first partition wall.

7. A plate material as described in claim 1 or claim 2, comprising a first layer including a plurality of said voids, and a second layer overlapping said first layer in the plate thickness direction and having a strength higher than that of said 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 second 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. A stringed instrument comprising a board as claimed in claim 1 or 2 and a string, wherein the second direction of the board substantially coincides with the longitudinal direction of the string.

Images