Damper for string instrument
BACKGROUND OF THE INVENTION 
     The present invention relates to a damper for a string instrument. 
     String instruments, such as guitars, ukeleles, mandolins, mandocellos and banjos, have been used for playing music from old times. Such a string instrument comprises a plurality of strings for vibrating to produce a sound of a desired pitch and tone when touched by a finger of a player, and a resonant body having a sound board provided with a sound hole for amplifying the sound produced from the strings. 
     Needless to say, the player of the string instrument must practice on his instrument over and over again with the aim to becoming a skilled musician. However, in this practical training, loud sounds are produced from these string instruments, which cause a nuisance to the neighbors. In order to relieve the neighbors of the nuisance caused by such loud sounds, the player shall endeavor not to produce loud sounds in his practical training. For this reason, a handy and yet practically serviceable damper for the aforementioned popular string instruments is highly desired. Until now, however, such a damper for the popular string instruments has not been commercially available. 
     SUMMARY OF THE INVENTION 
     It is, therefore, a primary object of this invention to provide a damper for string instruments which is handy and economical and can exert a strong effect for lowering the sounds produced from such string instruments. 
     Another object of this invention is to provide a damper for string instruments which is readily attached to and detached from such string instruments. 
     A further object of this invention is to provide a damper for the string instruments having a novel construction which facilitates manufacturing thereof. 
     According to this invention, there is provided a damper for the string instruments which comprises an elastic foldable web and a resilient spongy member secured to the inner surface of the foldable web. The elastic foldable web is provided with catch means positioned at the end portions thereof for fastening and damping the strings of the string instrument between the resilient spongy member, a hinge means positioned at the longitudinally central portion of the web for freely bending the web in an inward direction, and notched portions having sections of isosceles shape and disposed on the inner surface of the web close to and outer from the aforementioned hinge means. The notched portions provided at the both adjacent portions of the hinge means function to uniformly compress each string of the string instrument in cooperation with the resilient characteristic of the web as mentioned in detail in hereinbelow. 
     For a resilient member which is secured to the inner surface of the foldable web, it is unexpectedly found that a material having a continuous structure of small open-celled voids is preferred rather than a common acoustically absorptive material having closed-cellular voids. It is thus preferred as a resilient member of a damper according to this invention, a &#34;spongy member&#34; such as a moltprene, felt or an elastic synthetic rubber or plastics having open cells rather than a closed-cellular material such as a closed cellular rubber or a foamed thermoplastic or thermosetting resin having multiplicity of closed cells, e.g. closed-cellular polystyrene and ployurethane. In this instance, it should be appreciated that the terminology &#34;resilient spongy member&#34; as used herein means an elastic or resilient member having open-celled structure. 
     In a preferred embodiment of this invention, the elastic foldable web is composed of an integral strip of polypropylene and the hinge means is made up of a thin plane portion formed at the central portion of the polypropylene strip. 
    
    
     DRAWING 
     FIG. 1 is a sectional view of a preferred embodiment of the present invention in an open or relieved position. 
     FIG. 2 is a perspective view of a damper shown in FIG. 1, wherein the damper is attached to a string instrument and fastened for compressing the strings thereof. 
     FIG. 3 is a cross section taken at the location indicated by the line 3--3 in FIG. 1 but showing a modification. 
    
    
     DESCRIPTION 
     According to this invention, there is provided a damper for string instrument such as guitar, ukelele, mandolin, mandocello and banjo, which damper is particularly convenient in that it is handy and readily attached to and detached from the string instruments and that it has a novel construction which facilitates manufacturing thereof. 
     The damper of the invention, in general, comprises an elastic foldable web composed of a synthetic resin such as polypropylene and provided with a catch means, a hinge means and notched portions provided at the both adjacent portions of the hinge means; and a resilient spongy member. 
     The elastic foldable web serves both as a support means for the resilient spongy member and as a compression means for compressing strings of the string instrument associated with the functions of the hinge means, the notched portions and the resilient spongy member when the damper is attached to the string instrument and the catch means is fastened for holding the strings in between the resilient spongy member. The web may be made up of an integral strip of an elastic thermoplastic synthetic resin such as polypropylene, but it can be made up of a composite material, for example, composed of a flexible, continuous and thin strip of high pressure process polyethylene or polyester film and more rigid and elastic fragments of thermoplastic or thermosetting resin integrally melt-welded to from a continuous flexible film. The most preferred material for the web is a polypropylene film having a sufficient thickness for providing the desired compression force. 
     In the practical embodiments of this invention, the web is a few cm in width and a few mm in thickness. The length of the web may be varied in accordance with the special kind of the string instrument to which the damper is attached. 
     In the most preferred embodiment of this invention, the hinge means is a thin plane portion of a polypropylene strip, but it may be any other means provided that notched portions are provided at the vicinity of the both end portions thereof. 
     According to an important aspect of the present invention, there is provided, on the inner surface of the web and at the both sides of the hinge means, notched portions having sections of substantially isosceles shape, by the function of which the web of the damper can be curved in a substantially ellipsoidal configuration thereby for uniformly compressing the strings when the damper is attached to a string instrument. 
     The resilient spongy member is composed of a material as hereinbefore defined and secured to the inner surface of the elastic foldable web at the inner surfaces thereof and can be mutually applied to the inner surfaces thereof when the foldable web is bent inwardly and the catch means is fastened. 
     PREFERRED EMBODIMENT 
     A strip of a thermoplastic polypropylene having a thickness of 2 mm, a width of 3 cm and a length of 18.2 cm was prepared by cutting off from a polypropylene film. As shown in FIG. 1, on the inner surface of the thusly prepared web 1, notched portions 4 and 4 having the same configurations of substantially isosceles triangle shape were provided. At one end portion 1&#39; of the strip 1, there was provided a clasp having a hooked edge bent in an acute angle as is illustrated in the drawing. At the other end portion 3 of the strip 1, there was provided a wedge having a sectional configuration of letter V for engaging with the hooked edge disposed at the end portion 1&#39;. On the inner surface of the strip was secured a resilient member 2 made of a Moltprene and having an uniform thickness of 6 mm. 
     In a modification as illustrated by way of example in FIG. 3 the strip 1 is made up of a composite material comprising a thin strip 1a of high pressure process polyethylene and a more rigid strip 1b of thermosetting resin. The two strips are integrally melt-welded together to form a continuous unitary strip. 
     In the practical use of the damper, the strings 5 of the string instrument (not shown) are held in between the upper and lower layers of the resilient member 2, as shown in FIG. 2, and subsequently the engage means including a hooked edge and a wedge portions 1&#39; and 3 are fastened. In the closed and compressed position, the strings extend substantially perpendicularly to the longitudinal edge of the damper. The outer surfaces of the strip 1 is curved in a substantially ellipsoidal configuration under the influences of the elastic characteristic of itself and the notched portions 4. The contacting surface area 6 between the upper and lower layers of the resilient member 2 is formed, and thus the strings held therebetween are compressed and thereby the vibration of the strings are suppressed and the sounds produced from the strings are lowered.