JPH0116144Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a soundboard for a musical instrument using strings.

A soundboard needs to be able to quickly propagate transmitted vibrations to the entire surface of the soundboard, and for this reason, it is required to have high bending strength and low density. For example, in a conventional piano soundboard, as shown in Figure 1, several straight-grained boards 1 made of spruce or Scots pine are joined together to form the soundboard 2, and the surface of the soundboard 2 has wood grains (indicated by arrows). A piece 3 made of processed maple, beech, etc. is fixed in substantially the same direction as the sound board 2, and a sound rod 4 made of processed spruce, Scots pine, etc. is fixed on the back side of the soundboard 2 in a direction substantially orthogonal to the grain of the soundboard 2. There is.

As shown in FIG. 2, since the soundboard 2 is fixed to the bobbin 7 around the support frame 8, the ends of the soundboard 4 in the vicinity of the fixation are made thin to facilitate vibration.

However, natural woods such as spruce, Scots pine, beech, and maple are expensive, and because there are individual differences among woods, they have the disadvantage that even if they are processed into the same size and shape, a soundboard 2 of uniform quality cannot be obtained. There is. Furthermore, it is easily affected by changes in temperature and humidity, and has disadvantages such as a reduction in volume and tone.

Recently, as shown in Fig. 3, a soundboard 2 with a sanderch structure has been proposed, in which a core material 2' is made of a material with low specific gravity, and a surface material 2'' made of FRP, aluminum, etc. is adhered to the surface of the core material 2'. In the soundboard 2 having this structure, the bending strength in the orthogonal direction is almost equal, so the sounding rods 4
Although it is not necessary to use this, it has the disadvantage that it is difficult to reduce the stiffness near the support frame fixation, making it difficult to vibrate in the low frequency range. In order to compensate for this drawback, recently a soundboard structure has been proposed in which the peripheral part 2 of the soundboard 2 is made of materials such as FRP or phosphor bronze as shown in Figure 4, but generally there is discontinuity in a part of the elastic body. If there is a part, part of the wave will be reflected at that part, which will cause disturbance in the vibration form, which is undesirable. Also, due to changes over time, the soundboard 2 and the surrounding area 2
At the joint A, cracks occur due to stress concentration, and adhesive strength decreases at the bonded portion, making it extremely brittle and peeling off.

The present invention improves the above-mentioned drawbacks and provides a soundboard for a musical instrument that has a simple structure, streamlines manufacturing, and improves productivity.

That is, the soundboard of the musical instrument according to the present invention is characterized in that the soundboard and the bridge are integrally molded with foamed synthetic resin, and the bridge and the soundboard near the bridge are reinforced with carbon fiber or glass fiber.

The embodiments will be described below with reference to the drawings.
As shown in FIGS. 5 and 6, a soundboard is integrally molded with carbon fiber or glass fiber 6 disposed inside the soundboard 2 molded with foamed synthetic resin 5 and on the bridge 3 and the soundboard 2 below the bridge 3. It is the body. That is, the piece 3 is made of carbon fiber or glass fiber 6 in which the fibers are roving in one direction.
The fibers are arranged in the same direction as the longitudinal direction of the bridge 3, and the fibers are arranged in the soundboard 3 near the bridge 3 at the bottom of the bridge 3 in the area indicated by the broken line in FIG. Carbon fiber or glass fiber 6 with roving in the direction is arranged. For example, when using a urethane resin with a relatively high ratio E/P of density P and Young's modulus E as the foamed synthetic resin 5, a stock solution of isocyanate mixed with polyol, foaming agent, and foam stabilizer is injected into the mold. This allows them to be molded in one piece.

The soundboard of a musical instrument such as a piano constructed as described above can have a soundboard with excellent acoustic radiation efficiency because the foaming density of the synthetic resin can be changed arbitrarily, and it is made of carbon fiber or carbon fiber with high Young's modulus and density. Since glass fibers are used, the vibrations of the strings are quickly propagated to the entire surface of the soundboard by these fibers, and the Young's modulus of the peripheral members of the soundboard 2 is lower than that of the central member of the soundboard 2. A soundboard with excellent vibration characteristics can be obtained even in the sound range. Furthermore, unlike conventional wooden soundboards, there is no need for a sounding rod, so the structure is simple and easy to manufacture, and the weight of the soundboard is also reduced, which has the advantage of promoting an increase in volume and tone.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a conventional piano soundboard. FIG. 2 is a partially detailed sectional view of FIG. 1. Figures 3 and 4
The figure is a partially detailed sectional view showing an example of another conventional piano soundboard. Figure 5 is a front view of the soundboard of the present invention.
FIG. 6 is a detailed cross-sectional view taken along line A-A' in FIG. In the diagram, 1...straight-grained board, 2...sound board, 3...piece,
4... sound rod, 5... foamed synthetic resin, 6... carbon fiber or glass fiber, 7... beating, 8... pillar.

Claims (1)

[Scope of utility model registration request] In a piece-integrated soundboard of a musical instrument in which a soundboard and a bridge are integrally molded with foamed synthetic resin, carbon fiber is embedded in the front side of the bridge in the same direction as the longitudinal direction of the bridge, and the soundboard near the bridge is provided. A bridge-integrated soundboard for a musical instrument, characterized in that carbon fiber is embedded in the bridge in a direction substantially intersecting the longitudinal direction of the bridge to enhance the vibration characteristics of the strings and to strengthen the bridge and the soundboard.