1. Field of the Invention
This invention relates to wooden bars arranged on keyboards or frames of percussion instruments such as xylophones and marimbas.
2. Description of the Related Art
Generally, percussion instruments such as xylophones and marimbas have arranged multiple types of wooden or metal bars having different lengths on keyboards or frames, and players play these instruments by striking the bars with small hammers or mallets. Sounds produced by striking the bars resonate with designated pitches, which depend on the lengths of the bars.
As materials for use in the bars of the aforementioned percussion instruments, it is possible to use hardwood materials such as rosewoods, hard birches, padauks, and Chinese quinces as well as fiber reinforced plastics (FRP) such as carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics.
Japanese Unexamined Patent Publication No. Sho 60-159894 discloses an example of a bar-type percussion instrument using wooden bars having specific frequencies arranged on a keyboard or frame, wherein as shown in
Since the aforementioned bar is made of the prescribed wooden material, it may be superior in sound quality and (exterior) design. However, this bar has a relatively small thickness at the center portion corresponding to the formation of the hollow thereof and is fragile when struck with a mallet or the like. That is, there is a possibility that the bar may be easily broken or damaged due to fatigue caused by being repeatedly struck. In particular, a lower-pitch bar shown in
Japanese Unexamined Patent Publication No. Sho 51-127712 discloses another example of bars for use in percussion instruments, wherein bars are made of fiber reinforced plastics. That is, bars are produced by cutting fiber reinforced plastic materials into bars each having a prescribed shape. Since fiber reinforced plastic materials are hardly affected by weather conditions such as temperature and humidity, these bars are advantageous because they can be manufactured with uniform quality.
The bars made of fiber reinforced plastics may be highly improved in durability against striking; however, the player may experience a ‘hard’ striking feeling when striking these bars with a mallet. In addition, these bars have some drawbacks in sound quality because they produce only hard sounds and lack softness or mellowness, particularly in low pitch ranges. Since these bars are made of plastics, their exterior surfaces may lack luxuriousness in appearance and may be inferior in design. In addition, the bars made of fiber reinforced plastics may not be easily mechanically processed. Therefore, unlike the foregoing wooden bars as disclosed in Japanese Unexamined Patent Publication No. Sho 60-159894, these bars made of fiber reinforced plastics are hardly improved in sound quality by forming hollows on the undersides thereof.
Japanese Unexamined Patent Publication No. Sho 51-127712 also discloses another type of bar in which a wooden base layer is sandwiched between fiber reinforced plastic layers, which form exterior surfaces (sec FIG. 4). This bar may be improved in sound quality because the sound may efficiently propagate in the air and is retained for a relatively long time. However, when a hollow is formed in the underside of the bar, the aforementioned improvement in the sound quality may substantially vanish
It is an object of the invention to provide bars to be arranged in percussion instruments, which are increased in striking durability in low pitch ranges and produce sounds having superior sound quality, wherein the bars are also improved in design.
A prescribed number of bars are arranged in a percussion instrument such as a xylophone or marimba, wherein each bar of this invention is formed by a base layer, a fiber reinforced plastic layer, and a surface layer that are combined together using an epoxy adhesive therebetween. Both the base layer and surface layer is made of the prescribed hardwood material such as rosewood, hard birch, padauk, and Chinese quince, while the fiber reinforced plastic layer is formed by laminating one or more fiber reinforced plastic sheets, each of which is formed by impregnating and hardening thermosetting epoxy resin with fibers. All fibers can be aligned in a single direction that may be slanted by 45° or 90° against the longitudinal direction of the bar, for example. Alternatively, fibers are woven in two directions rectangularly crossing each other in a cloth form. Preferably, the base layer ranges from 10 mm to 30 mm in thickness, the fiber reinforced plastic layer ranges from 0.1 mm to 5 mm in thickness, and the surface layer (e.g., veneer) ranges from 0.1 mm to 5 mm in thickness. Thus, it is possible to noticeably improve bars in durability against striking with a mallet as well as in sound quality and design.
These and other objects, aspects, and embodiments of the present invention will be described in more detail with reference to the following drawing figures, in which:
This invention will be described in further detail by way of examples with reference to the accompanying drawings.
The base layer 1 is produced from the prescribed hardwood material such as rosewood, hard birch, padauk, and Chinese quince. That is, there is provided a relatively thick hardwood board whose thickness ranges from 10 mm to 30 mm, which is processed or cut into prescribed sizes and shapes.
The wooden surface layer 3 is produced from the prescribed hardwood material such as rosewood, hard birch, padauk, and Chinese quince. That is, there is provided a thin hardwood board whose thickness ranges from 0.1 mm to 5 mm, which is processed and cut into prescribed sizes and shapes.
As a material for use in production of the base layer 1 and the wooden surface layer 3, it is possible to select from among other wood materials generally known such as maple, hard maple, beech, mahogany, and birch.
As the fiber reinforced plastic layer 2, a single sheet or multiple sheets of fiber reinforced plastics are integrally laminated in a prescribed thickness ranging from 0.1 mm to 5 mm. Herein, the fiber reinforced plastic sheet is made using carbon fibers, which are impregnated into thermosetting epoxy resin and are hardened, for example.
The fiber reinforced plastic sheet is not limited in particular fiber directions. That is, it is possible to use the fiber reinforced plastic sheet whose fibers are aligned in a prescribed single direction. Alternatively, it is possible to use the fiber reinforced plastic sheet in which fibers are woven in two directions in the form of a cloth material. When the fiber reinforced plastic layer 2 is formed by laminating multiple fiber reinforced plastic sheets, it is possible to align fibers in a prescribed single direction in lamination, or it is possible to align fibers in two directions, which cross each other at a right angle or at a prescribed angle in lamination.
It is possible to adequately change dimensions of the base layer 1, fiber reinforced plastic layer 2, and surface layer 3 in conformity with the pitch (or interval) of the bar. In order to tune the pitch of the bar, one or multiple hollows 4 can be formed in the underside of the bar, which was conventionally demonstrated.
Specifically, the aforementioned bar can be produced by the following steps:
As described above, the bar of the present embodiment is constituted using the base layer 1 and the surface layer 3, both of which are made of wooden materials. Therefore, it is possible to produce a pleasant wood sound by striking the bar. In the tuning of the pitch of the bar, the hollow 4 can be formed on the underside of the base layer 1 by a relatively simple process. Due to the provision of the fiber reinforced plastic layer 2 arranged on the base layer 1, it is possible to improve the durability of the bar against striking. Therefore, it is possible to noticeably reduce likelihood that bars will be damaged or destroyed by being repeatedly struck. Since the surface layer 3 is made of the wooden material, the player may experience a relatively soft feeling when striking the bar. In addition, the appearance of the wooden surface layer 3 can be finished in a luxurious manner, so that the bar as a whole can be made with a good design.
The bar of the present embodiment may substantially match conventional bars in exterior appearance. Therefore, the bar-type percussion instrument can be constituted using mixtures of bars without causing differences in the overall appearance thereof. That is, bars of the present embodiment may be used in lower pitch ranges because lower-pitch bars whose thickness is greatly reduced due to the hollow, may be more easily damaged or broken, while conventional bars may be used in higher pitch ranges. Thus, the bar-type percussion instrument can be remarkably improved in both sound quality and durability.
Next, concrete examples of bars will be described in accordance with the present embodiment of the invention.
In order to test physical properties of bars, we, the inventors, actually produced twenty-eight types of bars, which are designated by test numbers ‘1’ to ‘28’ shown in FIG. 6. Herein, the twenty-eight types of bars are classified by three characteristics, namely, ‘fiber direction’, ‘number of laminated sheets’, and ‘laminated configuration of bar’. Specifically, the fiber direction designates the direction(s) in which fibers are aligned in each fiber reinforced plastic sheet, and the number of laminated sheets designates the number of fiber reinforced plastic sheets that are laminated together. As fibers, it is possible to use natural fibers, glass fibers, carbon fibers, and aramid fibers, for example.
In the table of
Next, a description will be given with respect to steps of producing the fiber reinforced plastic layer 2.
A more detailed description will be given with respect to steps of producing each of the bars whose test numbers range from ‘1’ to ‘24’ and each has the same laminated configuration consisting of ‘wood (veneer)+CFRP+wood’ (see FIG. 6).
Next, a detailed description will be given with respect to steps of producing each of bars whose test numbers range from ‘25’ to ‘28’ in FIG. 6 and each have the same laminated configuration consisting of ‘CFRP+wood+CFRP’. An example of this bar is shown in
In order to evaluate sound qualities of the aforementioned bars (i.e., test numbers 1 to 28) which are produced using carbon fiber reinforced plastic materials, an FFT (i.e., fast Fourier transform) analyzer is used to perform measurement with respect to resonant frequencies and vibration attenuation factors in the basic mode, second-order mode, and third-order mode, respectively. Then, calculations are performed based on measurement results to produce values with respect to the Young's modulus EL, ratio EL/GLT between the Young's modulus EL and rigidity (or compressibility) GLT, and internal loss tan δ. The values EL and EL/GLT are calculated by the analysis based on Timoshenko's theory, while values tan δ are calculated from vibration attenuation factors in prescribed frequency bands in proximity to the resonance frequency in the basic mode.
Specifically, a first physical value is produced based on the measurement result of the base layer 1 before lamination; then, a second physical value is produced based on the measurement result of the bar after lamination. In order to evaluate effects of the fiber reinforced plastic layer 2 arranged for the bar, a variation rate of the second physical value with reference to the first physical value is calculated in the following equation.
(variation rate in percentage (%))={(second physical value)−(first physical value)}/(first physical value)×100
In contrast to the aforementioned bars whose test numbers range from 1 to 24, the other bars whose test numbers range from 25 to 27 are extremely reduced in variation rates of the ratio EL/GLT, in particular in the negative direction. This may badly deteriorate the sound quality as wooden bars. In addition, the bar of the test number 26 provides a very large variation rate of tan δ; therefore, this bar is inferior in propagation and continuity of sound in the air. Furthermore, the bar of the test number 28 provides a very large variation rate of EL; therefore, this bar is badly degraded in sound quality as a wooden bar.
As described heretofore, this invention has a variety of effects and technical features, which will be described below.
As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the claims.
Number | Date | Country | Kind |
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2001-272647 | Sep 2001 | JP | national |
Number | Name | Date | Kind |
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4411187 | Roper et al. | Oct 1983 | A |
4649791 | Sawada et al. | Mar 1987 | A |
5333527 | Janes et al. | Aug 1994 | A |
5469769 | Sawada et al. | Nov 1995 | A |
6365812 | McGill | Apr 2002 | B1 |
Number | Date | Country |
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51 127712 | Nov 1976 | JP |
59 10994 | Jan 1984 | JP |
60 159894 | Aug 1985 | JP |
Number | Date | Country | |
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20030167899 A1 | Sep 2003 | US |