Patent Publication Number: US-9406285-B2

Title: Board for stringed instrument, method of manufacturing board for stringed instrument, and stringed instrument

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a board for a stringed instrument, a method of manufacturing a board for a stringed instrument, and a stringed instrument. 
     Priority is claimed on Japanese Patent Application No. 2013-219355, filed on Oct. 22, 2013, the content of which is incorporated herein by reference. 
     2. Description of Related Art 
     Front and back plates of a violin have partially different thicknesses so as to obtain satisfactory acoustic characteristics and have a unique camber shape of being gently curved to be convex toward a front or back surface side thereof. Front and back plates used in a viola, a cello, and a double bass belonging to the violin family also have a camber shape having partially different thicknesses as in the case of a violin. 
     In the related art, during the manufacture of front and back plates of the violin family, a solid wooden block is cut or carved to be formed in a camber shape having partially different thicknesses. However, when a solid wooden block is cut to manufacture front and back plates, there are problems in that time and labor are required due to a significantly large number of cutting processes, and the material yield is extremely low at about 10%. 
     Recently, as front and back plates of the violin family, plates in which a camber shape having partially different thicknesses is formed by press-bending a board having a smaller thickness than a wooden block to partially compress and curve the board have been manufactured (refer to p. 203, “VIOLIN, Instrument Encyclopedia”, published by Tokyo Ongaku-sha). 
     In addition, front and back plates of the violin family can also be manufactured by laminating a plurality of veneers adhered to each other by an adhesive to obtain laminated wood and bending the laminated wood to be gently curved. 
     In the front and back plates, since a camber shape is formed by bending, the number of cutting processes for forming the camber shape can be reduced. Accordingly, these front and back plates can be more efficiently manufactured as compared to the plates manufactured by cutting a wooden block, and the material yield is also improved. 
     However, in the front and back plates formed by press-bending a board, the thicknesses thereof are made to be partially different and a predetermined thickness distribution is formed by partially compressing the board. Therefore, the wood density in the compressed portion increases, and a variation in density is significantly large in the front and back plates. Even if front and back plates of the violin family have a unique camber shape, when a variation in density is large, a vibration during playing is different from the unique vibration of the violin family. Therefore, in a stringed instrument including a front plate and/or a back plate formed by press-bending, satisfactory acoustic characteristics may not be obtained. 
     In addition, in the front and back plates formed by press-bending, after the manufacture, a thickness distribution and a camber shape thereof are likely to be changed by a restoring force of compressed wood. Therefore, when a stringed instrument including the front and back plates formed by press-bending is used for a long period of time, acoustic characteristics may deteriorate, or there may be a damage caused by deformation of the front plate and/or the back plate. 
     On the other hand, in the front and back plates in which a camber shape is formed by bending laminated wood, the laminated wood is not partially compressed during the manufacture, and thus a variation in density is small. Accordingly, the above-described problems caused by the density in the front and back plates do not occur. 
     However, these front and back plates are uniform in thickness. Therefore, in a stringed instrument including these front and back plates, a vibration of the front and back plates during playing is different from the unique vibration of the violin family, and satisfactory acoustic characteristics may not be obtained. 
     In addition, there may be a case where a camber shape having partially different thicknesses is formed by press-bending laminated wood. However, in this case, since the laminated wood is partially compressed by press-bending, a variation in density is large in the front and back plates. 
     In addition, there may be a case where a camber shape having partially different thicknesses is formed by cutting laminated wood before or after bending the laminated wood. However, when the laminated wood is cut, a laminated cross-section is exposed to the surface, and a good appearance cannot be obtained. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a board for a stringed instrument which can be efficiently manufactured, has high material yield, has a small variation in density, has partially different thicknesses, has a shape of being curved to be convex toward one surface side thereof, and forms a front plate or a back plate having superior shape stability and acoustic characteristics. 
     In addition, another object of the present invention is to provide a stringed instrument which is not likely to be damaged by deformation of a front plate and/or a back plate and is superior in acoustic quality, the stringed instrument including a front plate and/or a back plate made of a board for a stringed instrument which can be efficiently manufactured and has high material yield. 
     According to an aspect of the present invention, there is provided a board for a stringed instrument which forms a front plate or a back plate of a stringed instrument, the board including: a veneer that includes a concave portion for partially reducing the thickness of the veneer, in which the veneer is curved to be convex toward one surface side. 
     According to another aspect of the present invention, there is provided a method of manufacturing a board for a stringed instrument which forms a front plate or a back plate of a stringed instrument, the method including: a process of forming a concave portion on a veneer so as to partially reduce the thickness of the veneer; and a process of curving the veneer to be convex toward one surface side. 
     According to still another aspect of the present invention, there is provided a stringed instrument including the board for a stringed instrument according to the aspect of the present invention. 
     In the board for a stringed instrument according to the aspect of the present invention which forms a front plate and a back plate of a stringed instrument, the veneer that includes a concave portion for partially reducing the thickness of the veneer is curved to be convex toward one surface side. Accordingly, in the board for a stringed instrument according to the aspect of the present invention, it is not necessary to partially compress the board in order for the board to have partially different thickness. Therefore, variation in the density of the board for a stringed instrument is small. Accordingly, when the board for a stringed instrument according to the aspect of the present invention is used as a front plate or a back plate, the unique vibration of the violin family is obtained during play, and the acoustic characteristics thereof are superior. 
     In addition, in the board for a stringed instrument according to the aspect of the present invention, partial compression of the board is not necessary, and thus a thickness distribution and a curved shape are not changed by a restoring force of compressed wood. Accordingly, the board for a stringed instrument according to the aspect of the present invention has superior shape stability as compared to front and back plates of the related art formed by press-bending. 
     In the board for a stringed instrument according to the aspect of the present invention, the veneer includes a concave portion for partially reducing the thickness of the veneer. In addition, the veneer is curved to be convex toward one surface side. Accordingly, the board for a stringed instrument according to the aspect of the present invention can be manufactured with a small number of cutting or carving processes as compared to the conventional case where the camber shape is formed by cutting or carving. As a result, the board for a stringed instrument according to the aspect of the present invention can be more efficiently manufactured as compared to the plates manufactured by cutting a wooden block, and the material yield is also improved. 
     The method of manufacturing a board for a stringed instrument according to the aspect of the present invention includes the process of curving the veneer, which includes the concave portion for partially reducing the thickness of the veneer, to be convex toward one surface side. Accordingly, a board for a stringed instrument having partially different thicknesses and a small variation in density can be obtained without partially compressing wood. In addition, in the method of manufacturing a board for a stringed instrument according to the aspect of the present invention, a board for a stringed instrument can be efficiently manufactured with a small number of cutting processes as compared to a case where deformation formed by the veneer being curved is formed by cutting. 
     In addition, the stringed instrument according to the aspect of the present invention includes the board for a stringed instrument according to the aspect of the present invention. As a result, the acoustic qualities are superior. In addition, the stringed instrument according to the aspect of the present invention is not likely to be damaged by deformation of a front plate and a back plate and thus can be used for a long period of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a cross-sectional view showing a front plate of a violin according to a first embodiment of the present invention in a width direction thereof (a cross-sectional view taken along line A-A′ of  FIG. 1B ), and  FIG. 1B  is a plan view showing the front plate shown in  FIG. 1A . 
         FIG. 2  is a perspective view showing a shape of a veneer used in the front plate shown in  FIGS. 1A and 1B . 
         FIG. 3  is a cross-sectional view showing a laminated plate which is formed when the front plate shown in  FIGS. 1A and 1B  is manufactured. 
         FIG. 4  is a side view showing a violin which is an example of a stringed instrument according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     &lt;First Embodiment&gt; 
     In this embodiment, a front plate of a violin will be described as an example of a board for a stringed instrument according to the present invention.  FIG. 1A  is a cross-sectional view showing a front plate of a violin according to a first embodiment of the present invention in a width direction thereof.  FIG. 1B  is a plan view showing the front plate shown in  FIG. 1A .  FIG. 1A  is a cross-sectional view taken along line A-A′ of  FIG. 1B   
     As shown in  FIG. 1A , the front plate  10  of the violin includes a laminated plate  11  which is curved to be convex toward the side of a front surface (top surface in  FIG. 1A ) and whose thickness gradually changes. 
     The laminated plate  11  includes a veneer  3  including a concave portion  34 . A front surface plate  1  is laminated on a front surface  3   a  of the veneer  3  by an adhesive  4 . In addition, a back surface plate  2  is laminated on a back surface  3   b  of the veneer  3  by the adhesive  4 . The front surface plate  1  and the back surface plate  2  are made of a veneer having a uniform thickness and function as a decorative sheet which covers the front surface  3   a  or the back surface  3   b  of the veneer  3 . In addition, the front surface plate  1  and the back surface plate  2  also have a function of reinforcing the veneer  3  along with the adhesive  4  to prevent deformation of the veneer  3 . 
     In the front plate  10  shown in  FIG. 1A , the veneer  3  is curved such that fiber of the veneer  3  extends along the curved shape of the veneer  3 . 
     On the back surface  3   b  (bottom surface of the veneer  3  in  FIG. 1A ), a concave portion  34  in which the depth of the bottom surface varies stepwise is formed. The concave portion  34  allows the thickness of the veneer  3  to be partially reduced and has a predetermined shape and a predetermined depth distribution in consideration of a function of the front plate  10  as a vibrating plate. 
     Regarding the thickness of the veneer  3 , as shown in  FIG. 1A , the thickness of peripheral edges  13  which are positioned outside the concave portion  34  in a plan view is the thickest. In addition, regarding the thickness of the veneer  3 , the thickness of thin portions  14  which are positioned between the peripheral edges  13  and a center portion  12  thinner than the peripheral edges  13  is the thinnest. As shown in  FIG. 1 , the thickness of the veneer  3  decreases stepwise from the peripheral edges  13  toward the thin portions  14  and increases from the thin portions  14  to the center portion  12 . 
     The thickness distribution of the veneer is determined according to performance required for a front plate or a back plate of a violin and is not limited to the thickness distribution of the veneer  3  shown in  FIG. 1A . For example, a configuration in which the peripheral edges are thin and the center portion is thick may be adopted. 
     Examples of the materials of the veneer  3 , the front surface plate  1 , and the back surface plate  2  include spruce, maple, pine, Japanese cedar, birch, beech, or lauan. Among these, spruce is preferably used because a high function of the front plate  10  as a vibrating plate can be obtained. 
     All the materials of the veneer  3 , the front surface plate  1 , and the back surface plate  2  may be the same, or all or a part of the materials may be different. In the embodiment, all of the veneer  3 , the front surface plate  1 , and the back surface plate  2  are made of spruce. As a result, a higher function as the front plate  10  can be obtained, and the acoustic quality of a violin using this front plate  10  can be further improved. 
     In the front plate  10  according to the embodiment, the front surface plate  1  is made of straight-grained spruce, and a fiber direction thereof is aligned to a length direction of the front plate  10  in plan view. As a result, a better appearance can be obtained. In addition, the front surface plate  1  of the front plate  10  has a continuous plane which is integrated by aligning end surfaces of two veneers to face each other at a center portion in a length direction of the front plate  10  and joining the end surfaces to each other. As a result, a good appearance having a joint at the center portion in the length direction of the front plate  10  is obtained. 
     In the front plate  10  shown in  FIG. 1A , the thicknesses of the front surface plate  1  and the back surface plate  2  are preferably 0.2 mm to 1.0 mm. The thicknesses of the front surface plate  1  and the back surface plate  2  may be the same as or different from each other. When the thicknesses of the front surface plate  1  and the back surface plate  2  are 0.2 mm or more, a function of coating the front surface of veneer  3  as a decorative sheet can be obtained, and a better appearance can be obtained. In addition, when the thicknesses of the front surface plate  1  and the back surface plate  2  are 0.2 mm or more, the front surface plate  1  and the back surface plate  2  can obtain a function of reinforcing the veneer  3  along with the adhesive  4  to prevent deformation of the veneer  3  and can improve the shape stability of the front plate  10 . In addition, when the thicknesses of the front surface plate  1  and the back surface plate  2  are 1.0 mm or less, the thickness of the veneer  3  can be sufficiently secured, and a thickness range of the front plate  10  which can be adjusted by the depth distribution of the concave portion  34  can be sufficiently secured. 
     The thickness of the front surface plate  1  is more preferably 0.3 mm or more. In this case, a cutting stock of the front surface of the laminated plate  11  can be sufficiently secured. Accordingly, even if the thickness distribution of the front plate  10  is finely adjusted or convex and concave portions present on the front surface of the front plate  10  are removed by cutting the front surface of the laminated plate  11  using, for example, a scraper, the front surface of the veneer  3  can be prevented from being exposed. In addition, the thickness of the front surface plate  1  is preferably 0.3 mm or more because a step which is formed by the concave portion  34  formed on the veneer  3  can be prevented from being taken over to front surface of the front plate  10  to form a convex portion. 
     As the adhesive  4 , one not containing a solvent such as water or an organic solvent is preferably used. Specifically, examples of the adhesive  4  not containing a solvent include a urethane-based adhesive, an epoxy-based adhesive, and a phenol-based adhesive. By using the adhesive not containing a solvent as the adhesive  4 , deformation of the front surface plate  1  and/or the back surface plate  2  caused by infiltration of an adhesive  4  into the front surface plate  1  and/or the back surface plate  2  can be prevented during the manufacture of the laminated plate  11 . Accordingly, the thickness distribution of the laminated plate  11  can be controlled with higher accuracy. 
     (Manufacturing Method) 
     In this embodiment, a method of manufacturing the front plate of the violin shown in  FIGS. 1A and 1B  will be described as an example of a method of manufacturing a board for a stringed instrument according to the present invention. 
     In order to manufacture the front plate  10  shown in  FIGS. 1A and 1B , first, the veneer  3  (refer to  FIG. 2 ) including the concave portion  34  is prepared. Next, the front surface plate  1 , the veneer  3 , and the back surface plate  2  are laminated in this order from below through the adhesive  4  to form a laminate  10   a  shown in  FIG. 3 . 
       FIG. 2  is a perspective view showing a shape of a veneer used in the front plate shown in  FIGS. 1A and 1B .  FIG. 3  is a cross-sectional view showing a laminated plate which is formed when the front plate shown in  FIGS. 1A and 1B  is manufactured. FIG.  3  is a cross-sectional view taken along line B-B′ of  FIG. 2 . 
     The veneer  3  shown in  FIG. 2  is larger than the external shape of the front plate  10  shown in  FIG. 1B . On the veneer  3 , the concave portion  34  for partially reducing the thickness of the veneer  3  is formed. In the concave portion  34 , the depth of the bottom surface varies stepwise as shown in  FIGS. 2 and 3 . The concave portion  34  can be formed using, for example, a method of cutting a veneer, which is to form the veneer  3 , to obtain a predetermined depth and a predetermined planar shape. 
     On the bottom surface of the concave portion  34 , as shown in  FIGS. 2 and 3 , a first bottom surface  31 , a second bottom surface  32 , and a third bottom surface  33  which have different depths are formed. The first bottom surface  31 , the second bottom surface  32 , and the third bottom surface  33  are flat, and a step is formed at a boundary portion of each bottom surface. The first bottom surface  31  having the deepest depth is provided in a region where the concave portion  34  overlaps with the thin portions  14  of the front plate  10  shown in  FIG. 1A  in a plan view. In addition, the second bottom surface  32  having the second deepest depth subsequent to the first bottom surface  31  is provided in a region where the concave portion  34  overlaps with the thin portions  14  and the center portion  12  in plan view. In addition, the third bottom surface  33  having the shallowest depth is provided so as to surround the outer edge of the second bottom surface  32 . 
     When the front surface plate  1 , the veneer  3 , and the back surface plate  2  are laminated to form the laminate  10   a  shown  FIG. 3 , fiber directions of the front surface plate  1 , the veneer  3 , and the back surface plate  2  may be the same as or different from each other. It is preferable that the fiber directions of the front surface plate  1 , the veneer  3 , and the back surface plate  2  be aligned to the length direction of the front plate  10  in consideration of a function of the front plate  10  as a vibrating plate. In particular, in consideration of a function of the front plate  10  as a vibrating plate, it is preferable that the veneer  3  be made of straight-grained wood and arranged such that the fiber direction of the veneer  3  is aligned to the length direction of the front plate  10 . It is preferable that the fiber direction of the front surface plate  1  be aligned to the length direction of the front plate  10  in consideration of the appearance of the front plate  10 . 
     In addition, a part of the fiber directions of the front surface plate  1 , the veneer  3 , and the back surface plate  2 , for example, a fiber direction of the back surface plate  2  may be aligned to the width direction of the front plate  10  in consideration of the strength and shape stability of the front plate  10 . 
     As the adhesive  4 , as described above, an adhesive not containing a solvent such as a urethane-based adhesive, an epoxy-based adhesive, or a phenol-based adhesive is preferably used. As the adhesive  4 , a thermal adhesive sheet may also be used. 
     Next, the laminate  10   a  shown in  FIG. 3  is curved to be convex toward one surface side. In the embodiment, the laminate  10   a  shown in  FIG. 3  is curved by placing the laminate  10   a  into a cavity of a metal mold and bending the laminate  10   a . As the metal mold, one in which an inside shape of the cavity corresponds to the cross-sectional shape of the front plate  10  is used. By bending the laminate  10   a  including the veneer  3  in which the concave portion  34  is formed using the above metal mold, the laminated plate  11  having a camber shape which has a small variation in density, has partially different thicknesses, and is curved to be convex toward one surface side can be obtained. 
     It is preferable that the bending process be performed under a condition where a compressive stress is not applied to the front surface plate  1 , the veneer  3 , and the back surface plate  2 . Accordingly, the laminated plate  11  has a uniform density similar to the intrinsic density of wood which forms the front surface plate  1 , the veneer  3 , and the back surface plate  2 . As a result, deformation of the manufactured front plate  10  can be further suppressed, and the front plate  10  can obtain superior acoustic characteristics intrinsic to wood. 
     In addition, a temperature condition of the bending process is not particularly limited and can be appropriately determined according to the kind of the adhesive  4  to be used. For example, when a thermoset adhesive is used as the adhesive  4 , it is preferable that the adhesive  4  be cured during the bending process by performing the bending process while performing a heat treatment to a predetermined temperature. 
     Next, the curved laminated plate  11  is cut using, for example, a saw along a visible outline (not shown) of the front plate  10  which is positioned outside the contour of the concave portion  34  of the veneer  3  in a plan view, thereby obtaining the front plate  10  having a predetermined external shape shown in  FIG. 1B . 
     Next, optionally, a finishing process may be performed in which the thickness distribution of the front plate  10  is finely adjusted or convex and concave portions present on the front surface of the front plate  10  are removed by cutting the front surface of the laminated plate  11  using, for example, a scraper. 
     Through the above-described processes, the front plate  10  shown in  FIGS. 1A and 1B  is obtained. 
     In addition, in the front plate  10  shown in  FIG. 1A , the veneer  3  that includes the concave portion  34  for partially reducing the thickness of the veneer  3  is curved to be convex toward one surface side. Accordingly, it is not necessary to partially compress wood in order for the wood to have partially different thickness. Therefore, a variation in density is small in the front plate  10 . Accordingly, when a violin including the front plate  10  shown in  FIG. 1A  is played, the unique vibration of the violin family can be obtained, and superior acoustic characteristics can be obtained. 
     In the front plate  10  shown in  FIG. 1A , it is not necessary to partially compress the wood. Therefore, a thickness distribution and a curved shape are not changed by a restoring force of compressed wood. Therefore, the front plate  10  shown in  FIG. 1A  has superior shape stability as compared to front and back plates of the related art formed by press-bending. 
     Further, in the front plate  10  shown in  FIG. 1A , the front surface plate  1 , the veneer  3 , and the back surface plate  2  are laminated and fixed through the adhesive  4 . Therefore, deformation of the front plate  10  is suppressed. 
     In addition, in the front plate  10  shown in  FIG. 1A , the veneer  3  including the concave portion  34  is curved to be convex toward one surface side. Accordingly, the front plate  10  shown in  FIG. 1A  can be manufactured with a small number of cutting processes as compared to a case where deformation formed by the veneer  3  being curved is formed by cutting or carving. Accordingly, the front plate  10  shown in  FIG. 1A  can be more efficiently manufactured as compared to the plates manufactured by cutting a wooden block, and the material yield is also improved. 
     In the front plate  10  shown in  FIG. 1A , the front surface plate  1  as a decorative sheet is laminated on one surface of the veneer  3  by the adhesive  4 . Accordingly, by using a material having superior design characteristic as a material of the front surface plate  1 , a good appearance can be obtained. 
     The method of manufacturing the front plate  10  shown in  FIG. 1A  includes the process of curving the veneer, which includes the concave portion  34  for partially reducing the thickness of the veneer, to be convex toward one surface side. Accordingly, the front plate  10  having partially different thicknesses and a small variation in density can be obtained without partially compressing wood. In addition, in the method of manufacturing the front plate  10  shown in  FIG. 1A , a board for a stringed instrument can be efficiently manufactured with a small number of cutting processes as compared to a case where deformation formed by the veneer being curved is formed by cutting. 
     &lt;Second Embodiment&gt; 
     In this embodiment, a back plate of a violin will be described as an example of a board for a stringed instrument according to the present invention. 
     The back plate of the violin according to the embodiment is different from the front plate  10  according to the first embodiment shown in  FIG. 1A , in that: the depth distribution and shape of the concave portion of the veneer are determined according to a thickness distribution in consideration of a function as the back plate. Further, in the second embodiment, veneers which are to form the front surface plate, the back surface plate, and the veneer are made of maple. 
     In the back plate according to the embodiment, it is more preferable that all of the front surface plate, the back surface plate, and the veneer be made of maple. By allowing all the front surface plate, the back surface plate, and the veneer to be made of maple, a higher function as the back plate can be obtained, and the acoustic quality of a violin using this back plate can be further improved. In addition, in the back plate according to the embodiment, a better appearance can be obtained by using maple having grain as the materials of the veneers which form the front surface plate. 
     The back plate of the violin according to the embodiment can be manufactured with the same method as the front plate  10  according to the above-described first embodiment. 
     In addition, with the back plate according to the embodiment, the same effects as the front plate  10  according to the above-described first embodiment can be obtained. That is, the back plate according to the embodiment can be efficiently manufactured and has high material yield. Accordingly, the back plate according to the embodiment has a small variation in density, has partially different thicknesses, has a shape of being curved to be convex toward one surface side, superior shape stability, a good appearance, and superior acoustic characteristics. 
     &lt;Stringed Instrument&gt; 
     In this embodiment, a violin will be described as an example of a stringed instrument according to the present invention.  FIG. 4  is a side view showing a violin which is an example of the stringed instrument according to the present invention. 
     In  FIG. 4 , the violin  50  includes a front plate  10 , a back plate  20 , a side plate  30 , and a neck  40 . 
     In the violin  50  shown in  FIG. 4 , the front plate according to the first embodiment is used as the front plate  10 . In the front plate  10  shown in  FIG. 4 , a f-hole (not shown) is formed at a predetermined position of the front plate  10  according to the first embodiment. 
     In the violin  50  shown in  FIG. 4 , the back plate according to the second embodiment is used as the back plate  20 . 
     The violin  50  can be manufactured with a well-known method of the related art by using the front plate according to the first embodiment as the front plate  10  and using the back plate according to the second embodiment as the back plate  20 . 
     Specifically, for example, the back plate  20  and the side plate  30  are bonded to each other using an adhesive such as glue. Next, the side plate  30  and the front plate  10  are bonded to each other using an adhesive such as glue to form a body. Next, the neck  40  is attached to the body, and the front surface is coated with varnish. Next, a fingerboard is attached, and a sound post is installed. Next, a bridge is installed, and strings are tensed. 
     Through the above-described processes, the violin  50  shown in  FIG. 4  is obtained. 
     The violin  50  can be manufactured by using the front plate according to the first embodiment as the front plate  10  and using the back plate according to the second embodiment as the back plate  20 , and thus has a good appearance and is superior in acoustic qualities. In addition, the violin  50  is not likely to be damaged by deformation of the front plate  10  and the back plate  20  and thus can be used for a long period of time. 
     &lt;Other Examples&gt; 
     The stringed instrument and the board for a stringed instrument according to the present invention are not limited to the above-described embodiments. 
     For example, the stringed instrument according to the present invention is not limited to a violin and may be a viola, a cello, or a double base belonging to the violin family. In addition, the present invention can also be applied to a stringed instrument, such as a guitar or the like, including a front plate and/or a back plate having a camber shape which is curved to be convex toward one surface side. 
     In the above-described example of the embodiments, the bottom surfaces having different depths are formed in three steps as the bottom surface of the concave portion of the veneer. However, the bottom surface may be a continuous curved shape. In addition, the number of depth steps of bottom surfaces having different depths is not particularly limited may be two, three as in the case of the above-described embodiments, or four or more. 
     In addition, in the above-described embodiment, a step is formed at the boundary portion between the bottom surfaces having different depths. However, an inclined surface for alleviating the step may be formed at the boundary portion between the bottom surfaces. 
     In addition, in the front plate  10  shown in  FIG. 1A , the concave portion  34  of the veneer  3  is formed on one surface of the veneer  3 . However, the concave portion may be formed on both surfaces of the veneer. In addition, a plurality of concave portions may be formed. 
     In addition, in the above-described example, the front plate  10  shown in  FIG. 1A  includes the front surface plate  1  and the back surface plate  2 . However, the front surface plate  1  and/or the back surface plate  2  are not necessarily provided. In addition, two or more front surface plates  1  and/or two or more back surface plate  2  may be provided. 
     When a board for a stringed instrument is a front plate not including a front surface plate, it is preferable that the veneer be made of straight-grained spruce in order to obtain a better appearance and high acoustic quality. When a board for a stringed instrument is a back plate not including a front surface plate, it is preferable that the veneer be made of maple having grain in order to obtain a better appearance and high acoustic quality. 
     In addition, when a front surface plate is not provided, the veneer may have a continuous plane which is integrated by aligning end surfaces of two veneers to face each other at a center portion in a length direction of a front plate or a back plate and joining the end surfaces to each other. 
     While preferred embodiments of the invention have been described and shown above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.