Music – Instruments – Stringed
Reexamination Certificate
2001-09-28
2004-01-27
Lockett, Kimberly (Department: 2837)
Music
Instruments
Stringed
C084S290000, C084S268000
Reexamination Certificate
active
06683236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a one piece composite guitar body and, more particularly, pertains to tailoring the sound produced by a stringed instrument by virtue of its construction.
2. Description of the Prior Art
Guitar bodies may be classified into 2 general types: electric and acoustic. The electric guitar body is traditionally solid, comprised typically of solid wood or wood laminations. The acoustic guitar body, relying solely on the vibration of the sound board and box, is traditionally hollow by design. This invention describes an improved guitar body made from composite materials that can be made into either an electric guitar body, or an acoustic guitar body, or a variation in between.
Traditionally, a solid body stringed instrument is one wherein the body lacks a cavity and a soundboard and which carries one or more electrical pickups. These pickups transform the string vibrations into electrical signals which are subsequently amplified and usually modified and then transformed into sound waves to create sounds related to string vibrations. Commonly, these bodies have been made from solid pieces of wood which are carved to define specific shapes including various recesses and openings for receiving bridges, pickups, and other components attached to the bodies.
The type of wood used on solid bodies varies but is limited to densities between 0.3 g/cm3 and 0.6 g/cm3 so that the weight and tonal qualities of the guitar are retained. These preferred woods are expensive and in some cases, rare and exotic. Some examples are basswood, swamp ash, alder, mahogany, and maple.
Despite the fact that electrical pickups in the solid body transform the string vibrations into various sounds, the solid body also effects the tone of the guitar. For example, softer woods such as basswood produce a somewhat deader, softer tone while harder woods such as alder produce a slightly brighter note with more sustain. This is because of the sympathetic relationship between the strings and the body. For example, a harder, stiffer wood will transmit string vibrations faster resulting in a note with more attack and a brighter sound.
It should be noted that these variations in tone due to different woods are limited because wood itself is limited to its internal structure of aligned cellulose fibers. Because of this, wood can be termed nearly homogeneous. The sound differences generated by different wood types can sometimes only be detected by an expert. Often, the type of strings and pickups used produce more tonal difference than the type of wood used.
The problems related to wood bodies for electric guitars have been numerous. Wood bodies, for example, change dimension when exposed to changes in temperature, humidity, or other environmental factors. These dimensional changes, at a minimum, result in tonal variations due to tension changes in the string and scale length changes. Long term effects can be more drastic such as warping and cracking which can leave the guitar useless.
Still another problem with wood used for solid body electric guitars is the large variation in densities of woods currently used. The fluctuations of density throughout a wood genus leave the guitar manufacturer in the position of manufacturing guitars which span a large range of weights and tonal qualities.
Additionally, wood used for the body of an electric guitar cannot withstand bumps normally associated with guitar playing, resulting in dents caused by such impacts.
There have been several attempts to create an electric guitar body using alternative synthetic materials. These attempts, however, have failed as a successful replacement for wood.
In the case of U.S. Pat. No. 5,054,356 of Farnell, Jr., a guitar body is described made primarily of rigid closed cell foam which is partially covered and bonded to flat panels of plastic sheet material having a thickness of about 2.5 mm (0.1 inches). An edge wall of plastic material is subsequently wrapped around the plastic sheet and foam sandwich thereby leaving the foam exposed. The theory is that the cells of the foam alternately pressurize and depressurize to enhance the musical output of the guitar. Because the foam is exposed, a deader sound is generated.
In the case of Cove, U.S. Pat. No. 4,185,534, the use of a foamed polymeric material to fabricate the body necessitated the neck continuing through the entire body. This is because the foam alone, due to the lack of structural fiber resin reinforcement, is not strong enough to hold the strings at tension. Furthermore, the large presence of exposed foam deadens the tone of the guitar and makes it susceptible to impact damage.
In U.S. Pat. No. 4,290,336 by Peavey, the body is molded into two major portions, like a clamshell, necessitating a secondary operation of screwing the two halves together. This method requires the addition of a trim molding in order to conceal the seam where the two halves are joined together. In addition, this design has connectors between the top and bottom surfaces, which limits the vibrational response of the shell of the body, which will reduce the tonal qualities of the guitar body. This results in a body with numerous interfaces which creates relative movement and damps the sustain of the note. This design, therefore, needs only polymeric materials, not composite materials as described in the present invention.
In the case of U.S. Pat. No. 4,334,453 of Morrison, a plastic shell is molded around a reduced dimension wood core. The wood is left exposed in the region of the pickups in order to retain the desired sound of wood. This invention produces essentially a wood guitar body with a plastic cover. The purpose of this method is to reduce the cost of the guitar body without having the inferior tonal qualities of plastic. This design does not behave like a unitary shell as described in the present invention.
In the case of Fishman, et. al. in U.S. Pat. Nos. 5,189,235, 5,305,674, and 5,337,644, a guitar body is described which is first cut out of a light weight soft wood, then covered with carbon fiber and fiberglass prepreg and bonded together in a secondary operation using a common vacuum bag process for consolidation pressure. The composite outer laminate offers reinforcement for the weaker soft wood used. This combination is used to produce a light weight guitar body but requires thin shapes in order to achieve the desired light weight. Furthermore, this design does not behave like a unitary shell as described in the present invention.
In the case of Soika, et. al., U.S. Pat. No. 4,144,793, a one piece acoustic guitar body is created through the use of conventional spin or rotocasting techniques. The body created is hollow, polymeric, and without fiber reinforcement. Due to the lack of fiber reinforcement, the design is limited because of the superior strength of the fiber composite and the lacks the options of customizing the tone of the guitar by varying the fiber type and orientation.
There have also been attempts to produce a hollow acoustic guitar body, but none have achieved the desired performance of a unitary shell of the present invention.
In the case of Jones, U.S. Pat. No. 4,213,370, a hollow plastic body is described with a rigid vertical outside wall, connecting to a sound board using a joint design. Although the patent mentions fiber reinforcements, it is proposed to produce this part via injection molding, thus limiting the fibers to short lengths without orientation. This limits the design due to limited strength, as evidenced by the bracing required and the joint design to attach the sound board. In the present invention using a unitary shell of continuous fiber reinforcement, the need for bracing and complex joint design is eliminated.
In the case of John, U.S. Pat. No. 4,408,516, a graphite fiber violin is described where the sound box of the violin is made from carbon fiber prepreg material. The top and bottom sound boards and side wall section are produced separately, then assembled together using a flexibili
Bash C. Malcolm
Chou Peter J. C.
Davis Stephen J.
Janes Richard
Dutkiewicz Edward P.
Lockett Kimberly
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