JPS6057895A - Resonation plate for musical instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a soundboard for a musical instrument that is easy to manufacture and is capable of sufficiently and favorably producing sounds from a low range to a high range.

[Prior art]

The soundboard of a stringed instrument, such as a piano, transmits the vibrations of the strings to the entire soundboard, increasing the sound quality, and producing good sound to the outside.The quality of the material, structure, etc., determines the sound quality and volume of the piano. It is no exaggeration to say that it primarily determines the length and duration of the sound. Therefore, as a soundboard, it has a light specific gravity and is highly elastic.
In addition, it is required that the vibration energy is absorbed little, and that vibrations are uniformly good especially from the bass to the treble region. For this reason, conventionally, soundboards have been formed using materials such as Japanese pine and spruce, but constructing them only from such natural materials is extremely expensive and requires a lot of work such as material selection, wood trimming, and chiseling. The specific modulus of elasticity Vρ is ridiculous because the process is complicated.
Since (E: Young's modulus, ρ: density) is limited by the value specific to wood, it has not been possible to expect a certain level of sound production efficiency.

For this reason, recently, a core material made of low specific gravity such as foam is used and fiber-reinforced resin sheets are laminated and glued on both sides, or wood is used as the core material and fiber-reinforced resin sheets are laminated on both sides. Various sound boards having a sandwich structure formed by bonding have been proposed. However, those using foam as a core material have the disadvantage that, because of their large internal loss, they lack volume, sound quality, and sound extension, especially in the high range, and the overall sound balance is poor. Furthermore, those using wood as the core material have a large ρ, a significantly low internal loss in the low frequency range, and a large high frequency range, so they also have the disadvantage of poor sound balance as a whole.

[Summary of the invention]

This invention was made in view of the above points,
By laminating and bonding a core material made of wood, a top plate and a back plate made of wood, and fiber-reinforced resin sheets interposed between the core material and the top plate, and between the core material and the back plate, the low To provide a soundboard for a musical instrument that can produce sounds from a range to a high range well, and can obtain a bright and balanced sound.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a perspective view of essential parts showing an embodiment of the musical instrument soundboard according to the present invention applied to a piano soundboard. In the same figure, a soundboard 1 is formed by joining a plurality of laminated boards 2 shown in FIG. 2 in the side direction thereof and wood-cutting them into a predetermined shape.

Describing the structure of the laminate 2 in detail, the laminate 2 has a core material 3 made of a wood veneer, and a front plate 4 and a back face plate 5 made of a wood veneer different from the core material 3 on the front and back surfaces of the core material 3, respectively. It is constructed by laminating and bonding through reinforced resin sheets 1-6 and 7.

As the material for the front plate 4 and the back plate 5, a spruce material having a light specific gravity and high elasticity is used, and the grain direction thereof coincides with the longitudinal direction of the laminate plate 2 as shown by arrow A. Further, the thickness of the front plate 4 and the back plate 5 are equal, for example, 3.
．． 75 rtan.

゛The core material 3 is made of the same tree species as the front and back materials, or has a shear modulus σ larger than that of the front board 4 and the back board 5,
A material having a small shear loss tangent -δ, such as Japanese cedar, butock, oreono, is used.

Among them, rice cedar, which has a low specific gravity, is preferably used.

The core material 3 is arranged with the grain direction aligned with the front plate 4 and the back plate 5, and the thickness of the core material 3 is set to 2 mm.

The fiber reinforced resin sheet 6.1 may be carbon fiber reinforced resin (CFRP) or glass fiber reinforced resin (GFRP).
etc., and among them, CFRP is preferably used. The reinforcing fibers of the sheet 6 and 70 are arranged continuously so as to coincide with the longitudinal direction of the laminate 2.

The manufacturing method for these sheets 6.1 includes, for example, impregnating carbon fibers arranged parallel to each other in one direction with an epoxy resin and pre-curing them to produce a prepreg sheet of continuous fibers. The epoxy resin may be cured by hot pressing with a press. Note that the sheets 6.7 each have a thickness of 0.25+a.

Thus, when a plurality of laminates 2 having such a configuration are joined together in the side direction, the grain direction (direction of arrow A) is aligned with the longitudinal direction of the laminate 2 over the entire surface, as shown in FIG. A matching soundboard 1 is obtained.

Next, the shear modulus σ of spruce, Japanese cedar, and CFRP
and shear loss tangent −δ are shown in a table.

Fig. 3 shows the change curve of the loss tangent -δ for each frequency obtained by vibration measurements of various soundboard pieces, and the solid line I is the front and back plate of this invention shown in Fig. 1 with a spruce plate thickness of 3.75 m and a core. Material rice cedar board thickness 21II111 Sheet CFRP thickness 0.25+
The curve of change caused by the soundboard (piece) 1 made of o+, the dotted line... is the curve of change caused by the soundboard 10 made of spruce material with a board thickness of iom, and the dashed line ■ is the change curve of the soundboard 10 made of spruce material with a board thickness of 9.5 nm.
This is a curve of change caused by a soundboard piece 11 formed by bonding sheets 13 and 14 made of carbon fiber reinforced resin having a thickness of 0.25111111 to the front and back surfaces of the soundboard piece 11.

As is clear from this figure, the change curve (
This curve is similar to the change curve (II) of the soundboard piece 10 made only of spruce material.The loss tangent -δ is uniformly small for each frequency component, and therefore the entire tone range,
In particular, the high-frequency range is well extended, producing a bright and well-balanced sound. On the other hand, the soundboard piece 11 has a significant feature that the loss tangent -δ in the bass range is extremely small.
It has the fatal disadvantage of large loss in the high frequency range and poor sound balance.

It is obvious that desired acoustic characteristics can be obtained by appropriately changing the thicknesses of the core material 3, front panel 4, back panel 5, etc. of the soundboard 1.

Further, although the above embodiment has been shown as a soundboard for a piano, the present invention is not limited to this, and it goes without saying that it may be applied to the top deck of a sounding body of a stringed instrument such as a guitar.

〔Effect of the invention〕

As explained above, the musical instrument soundboard according to the present invention has a core material made of wood, a front board and a back board made of wood, a front board and a back board made of wood, and a space between the core material and the top board and between the core material and the back board. Because it is laminated and bonded via fiber-reinforced resin sheets, it exhibits characteristics close to those of a wood soundboard across the entire frequency range, and has less loss of higher-order components than wood, resulting in improved sound quality. The volume and extension of the sound are improved, and the overall sound is bright, striped, and balanced, improving the performance of the instrument.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts showing an embodiment of the musical instrument soundboard according to the present invention applied to a piano soundboard, and FIG. 2 is a partially cutaway perspective view of a laminated board constituting the soundboard. FIG. 3 is a diagram showing internal loss change curves of various soundboard pieces. 1...Soundboard, 2...Laminated board, 3...Core material,
4...Front plate, 5...Back plate, 6.7...
Fiber reinforced resin sheet. Patent applicant: Nippon Musical Instruments Manufacturing Co., Ltd. Agent: Masaki Yamakawa (fυ・1 person)

Claims (1)

[Claims] A front plate and a back plate made of wood; a core material formed of wood and interposed between the front plate and the back plate;
A soundboard for a musical instrument, comprising the above-mentioned front plate and a core material, and fiber-reinforced resin sheets interposed between the back plate and the core material, and formed by integrally joining these members.