Music – Instruments – Stringed
Patent
1991-02-20
1992-12-15
Gelliner, Michael L.
Music
Instruments
Stringed
84291, 84452P, G01D 102
Patent
active
051719266
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a bow musical instrument, i.e. to an instrument belonging to the violin, viola, cello, and double-bass family.
Attempts have been made for many years, and without much success, to replace the wood used in instruments of this type by a composite material based on sheets of long fibers. The advantage of such a composite material lies in it remaining perfectly stable over time in spite of hygrometric and temperature variations, unlike wood. Another advantage lies in the theoretical possibility of having a material whose characteristics are constant and accurately identified, thereby making it possible to obtain repeatability in manufacture which is impossible when using wood. That is why industrial manufacture of violins made of wood has never yet given rise to remarkable instruments, and the violins concerned are used merely for study or practice.
Making violins out of composite material, i.e. in which at least the front is based on directed fibers (of carbon or of aromatic polyamides, etc.) disposed in layers that are crossed to a greater or lesser extent and are interconnected by resin, has always been a failure, since the sounds produced have never been able to achieve the richness of the sounds produced by a conventional instrument.
The present invention seeks to provide an instrument using a composite material as one of its components while avoiding the drawbacks of prior instruments.
To this end, the present invention therefore provides a bow musical instrument in which at least its front is constituted by a thin wall of composite material comprising at least two superposed sheets of crossed and directed long fibers, the wall being covered on at least one of its faces with a lining material of considerably lower density than the fibers, wherein the disposition of the sheets of fibers is such that the ratio of the longitudinal modulus of elasticity of the wall divided by the transverse modulus of elasticity of the wall is higher in a wall zone close to the longitudinal axis of symmetry of the instrument than it is for a zone close to the sides of the instrument.
It has been observed that a vibrating wall having these characteristics enables rich sounds to be produced comparable to those produced by good quality violins. Given the properties of a long fiber composite structure, the moduluses of elasticity depend essentially on the direction of the fibers and on the number of fibers in a given direction.
Thus, when considering an element of wall in cross-section and the projections of a unit length of each fiber passing through said element of the wall both onto the plane of the section and onto a plane perpendicular thereto, the product of the number of longitudinal projections multiplied by their length compared with the product of the number of transverse projections multiplied by their length is higher for an element of wall close to the center of the cross-section than it is for an element of wall close to its edges. In other words, two variant embodiments of the invention can be defined depending on whether action is taken on the number of sheets in the wall, which number varies from the center to the edge, or whether action is taken on the directions of the fibers in each sheet, for an identical number of sheets. Naturally, both possibilities may be combined.
In the general context of this structure, the composite structure can be modified locally to reinforce this or that portion of the wall, in particular in the vicinity of the sound post.
Embodiments of the invention are given in the following description in order to show up secondary characteristics and advantages.
Reference is made to the accompanying drawings, in which:
FIG. 1 is a front view of a violin in which at least its front is in accordance with the invention;
FIG. 2 is a side view of the FIG. 1 violin;
FIG. 3 is a section on line III--III of FIG. 2 through the front of the violin;
FIG. 4 is an enlarged view of an element of the section of FIG. 3; and
FIGS. 5 and 6 are diagrams showing two possible bas
REFERENCES:
patent: 3699836 (1972-10-01), Glasser
patent: 4364990 (1982-12-01), Haines
patent: 4408516 (1983-10-01), John
Besnainou Charles
Vaiedelich Stephane
Centre National de la Recherche Scientifique
Gelliner Michael L.
Spyrou Cassandra
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