Patent Description:
In stringed musical instruments such as guitars, a cutaway is formed around a portion of a body at which the body is connected to a neck, for improving playability when playing the guitar at the high position. Similar stringed instruments are known, for example, from Patent Literature <NUM>, <NUM> and <NUM>. Patent Literature <NUM> discloses a stringed musical instrument having a cutaway, wherein each of a plurality of braces is fixed to the back board such that two ends of each brace are located at an outer periphery of the back board. Accordingly, in this known musical instrument, the distance between the first end of a brace and a first edge portion of the back board is the same as the distance between the second end of a brace and a second edge portion of the back board. Non-Patent Literature <NUM> discloses a stringed musical instrument according to the preamble part of claim <NUM>.

The cutaway formed in the body of the guitar causes a natural frequency of a back board of the body to be increased. In this case, it is sometimes difficult to obtain a tone color similar to that of a guitar without the cutaway when the guitar strings are plucked.

In view of the above, the present disclosure relates to a technique of making a tone color of a stringed musical instrument having a cutaway more similar to that of a stringed musical instrument without a cutaway.

The cutaway formed in the body of the guitar leads to a decrease in an area of the back board or the like, so that the back board or the like has an accordingly increased rigidity. In particular, the rigidity of the back board at its portion around the cutaway to which a side board is fixed becomes higher than the other portion of the back board (e.g., a central portion of the back board). A plurality of braces, generally, transverse braces, are fixed to the back board for obtaining an enough strength (rigidity). In a case where the brace is fixed to a portion of the back board near the cutaway, the rigidity of the back board is further increased at that portion. For lowering the natural frequency of the back board in the guitar having the cutaway, it is necessary to decrease a degree of influence of the brace on the rigidity of the back board.

One aspect of the present disclosure relates to a stringed musical instrument according to claim <NUM>. An advantageous embodiment may be implemented according to claim <NUM>.

According to the stringed musical instrument constructed as described herein, the first brace, which is fixed to the back board at the closest position to the cutaway, has a dimension in the width direction of the back board smaller than the width of the back board at a position of the back board at which the first brace is fixed. Consequently, the degree of influence of the first brace on the rigidity of a portion of the back board located near the cutaway is lowered, as compared with the degree of influence of the first brace on the rigidity of the other portion of the back board. Further, the first brace is fixed to the back board so as to be disposed nearer to one side of the back board than another side thereof on which the cutaway is formed. In this arrangement, the first brace and the cutaway is spaced apart from each other, so that the above-indicated degree of influence of the first brace is further lowered. Consequently, it is possible to reduce a rate of increase in the natural frequency of the back board of the stringed musical instrument having the cutaway with respect to the natural frequency of the back board of a stringed musical instrument not having the cutaway. It is thus possible to permit the tone color of the stringed musical instrument having the cutaway to resemble the tone color of the stringed musical instrument not having the cutaway.

In a guitar not having the cutaway, the braces are conventionally fixed to the back board such that the longitudinal direction of the braces coincide with the width direction of the back board, namely, a direction perpendicular to a neck of the guitar. In contrast, in a guitar having the cutaway disclosed in Non-Patent Literature <NUM>, the braces are fixed to the back board such that the longitudinal direction of the braces is inclined with respect to the width direction of the back board. In this case, the natural frequency of the back board to which the braces are thus fixed is smaller than the natural frequency of the back board to which the braces are fixed such that the longitudinal direction of the braces coincides with the width direction of the back board.

In an instance where the braces are fixed in the inclined form as described herein, bilateral symmetry (right-left symmetry) of vibration distribution of the back board, namely, symmetry with respect to the neck of the guitar, is broken. In this instance, it is difficult to obtain the tone color similar to that of the guitar not having the cutaway. In the present disclosure, however, the braces need not be disposed in the inclined form, and the above-indicated bilateral symmetry is not broken.

Guitars disclosed in Patent Literature <NUM> and Non-Patent Literature <NUM> have a cutaway. As in the present disclosure, in each of the disclosed guitars, a brace, which is located at the closest position to the cutaway among a plurality of braces that are fixed to the back board, has a length smaller than a width of the back board at a position of the back board at which the brace is fixed. In the stringed musical instrument according to the present disclosure, however, transverse braces are fixed to the back board, namely, braces whose longitudinal direction coincides with the width direction of the back board are fixed to the back board. Thus, musical instruments according to the present invention differ from the guitar disclosed in Patent Literature <NUM>. In the stringed musical instrument according to the present disclosure, the brace, which is fixed to the back board at the closest position to the cutaway, is disposed nearer to one side of the back board than another side thereof on which the cutaway is formed. Consequently, the brace in question and the cutaway are spaced apart from each other. In this respect, the present stringed musical instrument differs from the guitar disclosed in Non-Patent Literature <NUM>.

The objects, features, advantages, and technical and industrial significance of the present disclosure will be better understood by reading the following detailed description of embodiments, when considered in connection with the accompanying drawings, in which:.

<FIG> is a perspective view of a guitar <NUM> according to one embodiment of the present disclosure. The guitar <NUM> is a guitar having a hollow body such as an acoustic guitar. As shown in <FIG>, the guitar <NUM> includes the body <NUM>, a neck <NUM>, and strings <NUM>. The body <NUM> includes a front board <NUM>, a side board <NUM>, and a back board <NUM>. A cutaway <NUM> is formed near a portion of the body <NUM> at which the body <NUM> is connected to the neck <NUM>. The cutaway <NUM> is formed for improving playability of the guitar <NUM> when playing the guitar <NUM> by pressing down the string(s) <NUM> at the high position. In the following explanation, a direction parallel to the neck <NUM> is referred to as a longitudinal direction of the back board <NUM>, and a direction perpendicular to the neck <NUM> is referred to as a width direction of the back board <NUM>.

Each of the front board <NUM> and the back board <NUM> is formed of a flat board obtained by cutting wood into a predetermined shape. The front board <NUM> and the back board <NUM> are substantially identical in shape and are opposed to each other with a space interposed therebetween. The side board <NUM> is a band-like board having a contour following a contour of the front board <NUM> and the back board <NUM>. The side board <NUM> connects outer peripheries of the front board <NUM> and the back board <NUM> over entire circumferences thereof. A space defined by the boards <NUM>-<NUM> functions as an acoustic space in which vibration of the strings <NUM> is resonated.

As shown in the front view of <FIG> showing an inner surface of the back board <NUM>, braces 14_1 to 14_4, each of which is a bar-like member, are bonded to the inner surface of the back board <NUM> by an adhesive, for instance. The braces 14_1 to 14_4 are reinforcing members for ensuring strength (rigidity) of the back board <NUM>. The braces 14_1 to 14_4 are transverse braces extending in the width direction of the back board <NUM>. The braces 14_1 to 14_4 are fixed to the back board <NUM> at respective positions of the back board <NUM> in the longitudinal direction such that a longitudinal direction of the braces 14_1 to 14_4 coincide with the width direction of the back board <NUM> and such that the braces 14_1 to 14_4 are equally spaced apart from each other in the longitudinal direction of the back board <NUM>.

As shown in <FIG>, the brace 14_1 (as one example of a first brace) is fixed to the back board <NUM> such that the brace 14_1 is located at the closest position to the cutaway <NUM> among the braces 14_1 to 14_4. Opposite end portions of the brace 14_1 are cut away such that the thickness of the brace 14_1 perpendicular to the plane of the back board <NUM> is smaller at the opposite end portions of the brace 14_1 than at a central portion thereof. In an instance where the width direction of the back board <NUM> is defined as a right-left direction, the brace 14_1 has a shape that is symmetric in the right-left direction, i.e., a bilateral symmetric shape. The braces 14_2 to 14_4 also have a shape that is symmetric in the right-left direction.

In the present embodiment, the brace 14_1 has a length, i.e., a dimension in the width direction of the back board <NUM>, smaller than the width of the back board <NUM> at a position of the back board <NUM> at which the brace 14_1 is fixed. (The position at which the brace is fixed will be hereinafter referred to as "brace-fixed position" where appropriate). Preferably, the length of the brace 14_1 is not smaller than <NUM>% and not larger than <NUM>% of the width of the back board <NUM> at the brace-fixed position. More preferably, the length of the brace 14_1 is not smaller than <NUM>% and not larger than <NUM>% of the width of the back board <NUM> at the brace-fixed position. As shown in <FIG>, two edge potions on an outer periphery of the back board <NUM>, which interest a line extending in the width direction of the back board <NUM> at the brace-fixed position (i.e., in a direction of extension of the brace 14_1), are respectively referred to as a first edge portion 13a near to the cutaway <NUM> and a second edge portion 13b remote from the cutaway <NUM>. Further, one of opposite ends of the brace 14_1 near to the cutaway <NUM> is referred to as a right end 14_1a, and the other of the opposite ends of the brace 14_1 remote from the cutaway <NUM> is referred to as a left end 14_1b. In this case, the length of the brace 14_1, namely, a distance between the right end 14_1a and the left end 14_1b of the brace 14_1, is not smaller than <NUM>% and not larger than <NUM>% of a distance between the first edge portion 13a and the second edge portion 13b of the back board <NUM>, and more preferably, not smaller than <NUM>% and not larger than <NUM>% of the distance between the first edge portion 13a and the second edge portion 13b. In the present embodiment, the brace 14_1 is fixed to the back board <NUM> so as to be disposed nearer to one side of the back board <NUM> than another side thereof on which the cutaway <NUM> is formed, namely, the brace 14_1 is fixed on the left side of a central portion of the back board <NUM> at which the neck <NUM> is connected. In this instance, the brace 14_1 is fixed to the back board <NUM> such that a distance between the right end 14_1a of the brace 14_1 and the first edge portion 13a of the back board <NUM> is larger than a distance between the left end 14_1b of the brace 14_1 and the second edge portion 13b of the back board <NUM>. Thus, the brace 14_1 and the cutaway <NUM> are moderately spaced apart from each other, and the brace 14_1 and the outer periphery of the back board <NUM> on the one side thereof opposite to another side thereof on which the cutaway <NUM> is formed are moderately spaced apart from each other. For instance, the length of the brace 14_1 may be determined such that the left end 14_1b is located near the outer periphery of the back board <NUM> on the one side thereof opposite to another side thereof on which the cutaway <NUM> is formed (or such that the left end is located at a position that is moderately distant from the outer periphery of the back board <NUM> on the one side) and such that the right end 14_1a is located around the bottom of the cutaway <NUM> in the longitudinal direction of the back board <NUM>, namely, the right end 14_1a is located at a position of the back board <NUM> that is downwardly distant from a curvature start position A at which the cutaway <NUM> starts to curve.

In the present embodiment, the shortest distance between: the brace 14_1: and a part of the outer periphery of the back board <NUM> that faces the cutaway <NUM>, namely, a part of the outer periphery of the back board <NUM> that defines a curved portion of the cutaway <NUM>, is not smaller than a predetermined distance. In the example shown in <FIG>, the left end 14_1b of the brace 14_1 is fixed to the back board 13x near the side board <NUM>, and the right end 14_1a of the brace 14_1 is fixed to the back board <NUM> at a position thereof that is downwardly distant, by the predetermined distance, from a position B at which the cutaway <NUM> is the deepest. The predetermined distance (the shortest distance) is preferably not smaller than <NUM>, and more preferably in a range from <NUM> to <NUM>. The position at which the right end 14_1a of the brace 14_1 is fixed may be determined based on the above-indicated curvature start position A of the cutaway <NUM>.

As shown in <FIG>, the braces 14_2 to 14_4 are fixed below the brace 14_1. Each of the braces 14_2 to 14_4 has a length, i.e., a dimension in the width direction of the back board <NUM>, that is substantially equal to the width of the back board <NUM> at the corresponding position of the back board <NUM> at which each of the braces 14_2 to 14_4 is fixed. Each of the braces 14_2 to 14_4 has a thickness smaller at its longitudinally opposite end portions than at its central portion.

The guitar <NUM> of the present embodiment is thus constructed.

When the guitar strings are plucked, there is generated, in the back board <NUM>, a natural vibration with the outer periphery of the back board <NUM> acting as a fixed end. In this case, the natural frequency of the back board <NUM> is determined based on the rigidity of the back board <NUM>, namely, a degree of difficulty in deformation, the shape of the back board <NUM>, and so on.

The cutaway <NUM> formed in the body <NUM> leads to a reduction in the area of the back board, and the rigidity of the back board <NUM> is accordingly increased. The braces fixed to the back board further increases the rigidity of the back board. Consequently, the natural frequency of the back board will increase if any suitable measure to restrain the natural frequency from increasing is not taken, and it is impossible to obtain a tone color which is similar to that of a guitar without the cutaway when the guitar strings are plucked.

In the present embodiment, the brace disposed at the closest position to the cutaway <NUM> is the brace 14_1 whose length is smaller than the width of the back board <NUM> at the position thereof at which the brace 14_1 is fixed. Thus, the degree of influence of the brace 14_1 on the rigidity of the back board <NUM> at its portion near the cutaway <NUM> is decreased.

In the present embodiment, the brace 14_1 is located at the position of the back board <NUM> distant, by a suitable distance, from the outer periphery of the back board <NUM> that faces the cutaway <NUM>, resulting in a further decrease in the above-indicated degree of influence of the brace 14_1 on the rigidity of the back board <NUM> at its portion near the cutaway <NUM>. Consequently, it is possible to reduce a rate of increase in the natural frequency of the back board <NUM> of the guitar <NUM> having the cutaway <NUM> with respect to the natural frequency of the back board <NUM> of the guitar <NUM> not having the cutaway <NUM>.

In the present embodiment, the braces 14_1 to 14_4 are fixed to the back board <NUM> such that the longitudinal direction of the braces 14_1 to 14_4 coincides with the width direction of the back board <NUM>. Thus, bilateral symmetry (right-left symmetry) of vibration distribution of the back board <NUM>, i.e., symmetry with respect to the neck <NUM> of the guitar <NUM>, is not broken in the present embodiment, unlike in the conventional arrangement.

According to the present embodiment, it is possible to permit the tone color of the guitar having the cutaway to resemble the tone color of a guitar not having the cutaway.

<FIG> are views for explaining advantages of the present embodiment. <FIG> is a view showing frequency characteristics of the guitar <NUM> of the present embodiment, and <FIG> is a view showing frequency characteristics of a guitar of a comparative example. The guitar of the comparative example differs from the guitar <NUM> of the present embodiment only in that the brace disposed the closest to the cutaway <NUM> among a plurality of braces fixed to the back board <NUM> has a length substantially equal to the width of the back board <NUM> at a position of the back board <NUM> at which the brace is fixed. In each of <FIG>, an arrow is attached to waveforms of respective frequencies of a basic mode and a secondary mode. Comparison of the two graphs reveal that a ratio of a relative sound pressure level in the basic mode with respect to a relative sound pressure level in the secondary mode is large, as shown in <FIG>. According to the present embodiment, the tone color in the bass range is emphasized, and the guitar having the cutaway in which the tone color in the treble range tends to be emphasized has the tone color closer to the tone color of the guitar not having the cutaway.

Claim 1:
A stringed musical instrument including a body (<NUM>) in which a cutaway (<NUM>) is formed,
wherein the body includes a back board (<NUM>) on which at least one brace (14_1-14_4) is provided so as to extend in a width direction of the back board, a longitudinal direction of each of the at least one brace coinciding with the width direction of the back board, wherein
a first brace (14_1), which is the closest to the cutaway among the at least one brace (14_1-14_4), has a dimension in the width direction of the back board smaller than a width of the back board at a position of the back board at which the first brace is fixed, the first brace being fixed to the back board such that a distance between a first end (14_1a) of the first brace (14_1) and a first edge portion (13a) of the back board (<NUM>) is larger than a distance between a second end (14_1b) of the first brace (14_1) and a second edge portion (13b) of the back board (<NUM>), two edge portions on an outer periphery of the back board (<NUM>) in the width direction at the position of the back board (<NUM>) at which the first brace (14_1) is fixed including the first edge portion (13a) and the second edge portion (13b) that is farther from the cutaway (<NUM>) than the first edge portion (13a), the first end (14_1a) of the first brace (14_1) and the second end (14_1b) of the first brace (14_1) being opposite ends of the first brace (14_1), the first end (14_la) of the first brace (14_1) being nearer to the cutaway (<NUM>) than the second end (14_lb) of the first brace (14_1)
characterized in that
the first end (14_1a) of the brace (14_1) is fixed to the back board (<NUM>) at a position that is downwardly distant, by a predetermined distance, from a position at which the cutaway (<NUM>) is the deepest, the predetermined distance being not smaller than <NUM>, and
the first brace (14_1) has a thickness in a direction perpendicular to the back board (<NUM>) smaller at its opposite end portions in the width direction than at its central portion in the width direction, and
the first brace (14_1) has a shape that is symmetric in the width direction of the back board (<NUM>).