Abstract:
A stringed musical instrument that is convertible between fretted and fretless playing configurations includes a body, a neck connected to the body at one of its ends, a fingerboard disposed on the neck, a plurality of movable frets spaced apart at positions along the fingerboard, a plurality of strings disposed above the frets, and, according to one aspect of the invention, at least one rod that extends through the frets, wherein the at least one rod is configured to function both as a spring and as a device for retaining the frets in the fingerboard. According to another aspect of the invention, at least one strip of material separates a metallic component of a fret adjustment device from another component of the instrument that is formed from metal, wherein the at least one strip of material is configured to provide permanent dry lubrication for the metallic component of the fret adjustment device. According to still another aspect of the invention, the fret adjustment device includes a plate member disposed in the body of the instrument and at least one cam rod extending beneath the plurality of frets, the plate member having at least one aperture disposed therein, wherein the at least one aperture of the plate member forms a passive connection with one end of the at least one cam rod.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority to, and incorporates by reference in its entirety, pending U.S. Provisional Patent Application No. 61/341,325, entitled “Stringed Musical Instrument Convertible From Fretted to Fretless”, filed on Mar. 30, 2010. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable. 
       NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable. 
       INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK 
       [0004]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The invention generally relates to stringed musical instruments. More particularly, the invention relates to a stringed musical instrument that is easily convertible between fretted and fretless playing configurations. 
         [0007]    2. Description of Related Art 
         [0008]    Stringed musical instruments, such as guitars and bass guitars, come in several different varieties. A first variety of stringed musical instruments generally comprises a body affixed to a first end of an elongated neck, a fingerboard disposed on the top portion of the elongated neck, and a headstock with tuning pegs and tuning knobs affixed to a second end of the neck, which is opposite to the first end thereof. A plurality of strings are disposed above the upper surface of the fingerboard, and are fixedly attached to the body at one end and adjustably attached to the tuning pegs of the headstock at the other end. The tuning pegs enable the tension of the strings to be adjusted, which in turn, alters the pitch of the strings. Each of the plurality of strings is stretched between a bridge positioned on the body and a nut positioned at the distal end of the neck near the headstock. A second variety of stringed musical instruments, like the first variety, includes a body affixed to an elongated neck, a fingerboard disposed on the top portion of the elongated neck, and strings disposed above the upper surface of the fingerboard. However, unlike the first variety of stringed musical instruments, the second variety does not include a headstock with tuning pegs and thus, is commonly referred to as having a headless neck. A headless bass is one such example of this second variety of stringed musical instruments. On a stringed musical instrument with a headless neck, the tuning mechanisms are typically located as a part of the bridge or behind a bridge. 
         [0009]    In order to play a stringed musical instrument, a musician strums or plucks the strings with one hand while varying the useful or active length of the string with the other hand by pressing the strings against the fingerboard at selected positions along the length thereof. The variation in the useful or active length of the strings results in a consequential variation in the pitch of the string. 
         [0010]    Stringed musical instruments can be generally categorized as fretted instruments and unfretted instruments. As the names suggest, a fretted instrument is an instrument that contains frets disposed along the length of its fingerboard, whereas an unfretted instrument is an instrument that has no frets on its fingerboard. 
         [0011]    When playing a fretted instrument, a musician uses his or her fingers to press a string of the instrument against the fingerboard behind a selected fret on a side of the fret that is opposite to the body, so that the string contacts the fret and its useful vibrating length is reduced to the distance between the fret and the bridge. By selecting the correct fret, the musician is able to more easily achieve an acceptable level of intonation because the positions for the correct notes are defined by the placement of the frets. Thus, a fretted stringed musical instrument is able to produce a discrete series of notes and a sharp, clearly defined pitch. Due to these characteristics, fretted instruments are much easier for playing chords. 
         [0012]    When playing a fretless instrument, a musician uses his or her fingers to press a string of the instrument against the fretless fingerboard so that the useful vibrating length of the string is reduced to the distance between the point where the musician&#39;s fingertip presses the string against the fingerboard and the bridge. Instruments without frets tend to produce a softer sound with a broader range of selectable pitches because, unlike fretted instruments, the selectable vibrating lengths of the strings are not limited by the predetermined positions of the frets disposed along the length of a fingerboard. Consequently, fretless instruments enable musicians to produce sounds that not available from fretted instruments. 
         [0013]    The modern playing styles of some musicians, as well as the requirements of certain musical compositions, has created a need for the ability to easily play both fretted and fretless instruments within the context of a single song. While a musician can always purchase both fretted and fretless instruments, and alternate between these two instruments while playing a song that requires the use of both, utilizing separate instruments creates various problems. First, it is expensive to purchase separate fretted and fretless instruments. Secondly, it is inconvenient for the musician to transport both types of instruments to the location of his or her performance. Third, during some musical compositions, the musician simply does not have enough time to switch between separate fretted and fretless instruments. Thus, a stringed musical instrument that is easily and quickly convertible between fretted and fretless playing configurations is necessary to overcome these abovementioned problems. 
         [0014]    While others have designed different ways to incorporate fretted and fretless modes of operation in the same instrument, the related art devices have numerous limitations and drawbacks. For example, some of these convertible musical instruments utilize gearing mechanisms having a large number of individual components to adjust the position of the frets. Not only are gearing mechanisms subject to substantial wear over time, they also add complexity to the adjustment device and lead to increased manufacturing costs. Other convertible stringed musical instruments of the related art employ interchangeable fingerboards, one being provided with frets, and the other being provided without frets. The use of interchangeable fingerboards is particularly problematic when the instrument must be converted during a single song. After all, it is very difficult, and sometimes impossible, for a musician to swap one fingerboard for another without substantially disrupting the performance of the musical composition. Still other convertible musical instruments taught by the related art utilize an arrangement of components that significantly interferes with the ergonomics of the instrument, thereby making it more difficult to play. While other convertible musical instruments of the related art use intricately formed components with complex geometries that are both difficult and expensive to manufacture and/or utilize a component design that impedes serviceability of the instrument. 
         [0015]    Thus, there is a great need for a stringed musical instrument that is easily and quickly convertible between fretted and fretless playing configurations, is simple and inexpensive to manufacture, is easy to disassemble and repair, and has good ergonomics. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    Accordingly, the present invention is directed to a stringed musical instrument convertible between fretted and fretless playing configurations that substantially obviates one or more problems resulting from the limitations and deficiencies of the related art. 
         [0017]    A first object of the present invention is to provide a convertible stringed instrument that utilizes very few extra parts as compared to a standard non-convertible instrument, and far fewer additional parts as compared to other convertible instruments. 
         [0018]    A second object of the present invention is to provide a convertible stringed musical instrument that employs a fret adjustment device with components that are both easier to fabricate and less expensive than those of other convertible instruments. 
         [0019]    A third object of the present invention is to provide a convertible stringed musical instrument that employs a fret adjustment device with components that are more durable than those employed by other convertible instruments. 
         [0020]    A fourth object of the present invention is to provide a convertible stringed musical instrument that has minimal added weight as compared to a standard non-convertible instrument, and less additional weight than that added by other convertible instruments. 
         [0021]    A fifth object of the present invention is to provide a convertible stringed musical instrument that contains no gears, no welded parts, no rivets, no metal castings, and no metal springs to rattle or break. 
         [0022]    A sixth object of the present invention is to provide a convertible stringed musical instrument that does not substantially limit the neck or body design of the instrument. 
         [0023]    A seventh object of the present invention is to provide a convertible stringed musical instrument that employs a fret adjustment device with parts that are easily removable for repair or replacement, if needed, without damaging the neck or the body of the instrument. In general, the fret adjustment device of the present invention is much easier to repair than the devices used by other convertible instruments. 
         [0024]    An eighth object of the present invention is to provide a convertible stringed musical instrument with a neck that can be easily removed and reinstalled on the instrument body in the same manner as a standard bolt-on neck system. Overall, the convertible instrument of the present invention is much easier to assemble and disassemble than other convertible instruments. 
         [0025]    A ninth object of the present invention is to provide a convertible stringed musical instrument that can be quickly switched between fretted and fretless modes during the normal playing of the instrument without the need for any tools. 
         [0026]    A tenth object of the present invention is to provide a convertible stringed musical instrument that employs a fret adjustment device with an actuator mechanism that in no way interferes with the normal playing style of the instrument. Overall, the ergonomics of the fret adjustment device utilized by the present invention are superior to that of other convertible instruments. 
         [0027]    An eleventh object of the present invention is to provide a convertible stringed musical instrument that enables a conventional tension rod system to be used for the overall adjustment of neck curvature. Some other convertible instruments do not allow a conventional tension rod system to be utilized. 
         [0028]    A twelfth object of the present invention is to provide a convertible stringed musical instrument that employs a fret adjustment device which does not require the use of any gears at the end of the neck. 
         [0029]    The aforedescribed objects are merely illustrative in nature. Additional objects and advantages of the present invention will be apparent from the following detailed description, the accompanying drawings, and the appended claims. 
         [0030]    To achieve one or more of these objects and advantages, in accordance with a first aspect of the present invention, there is provided a stringed musical instrument convertible between fretted and fretless playing configurations that includes: a body; a neck, the neck being connected to the body at one of its ends; a fingerboard disposed on the neck; a plurality of movable frets spaced apart at positions along the fingerboard; a plurality of strings disposed above the frets; and at least one rod that extends through the frets. In this embodiment, the at least one rod is configured to function both as a spring and as a device for retaining the frets in the fingerboard. 
         [0031]    In a preferred embodiment of this aspect of the present invention, the at least one rod is formed from a polymer. In another preferred embodiment, the at least one rod comprises a plurality of rods. In yet another preferred embodiment, the at least one rod comprises a plurality of rods, each being formed from a polymer. 
         [0032]    In still another preferred embodiment, when the frets are in a raised position, the at least one rod is elastically deformed at a plurality of sections along its length. In yet another preferred embodiment, when the frets are in the raised position, the at least one rod comprises a plurality of upwardly curved portions, each of the plurality of upwardly curved portions corresponding to one of the plurality of sections along its length at which it is elastically deformed. 
         [0033]    In accordance with a second aspect of the present invention, there is provided a stringed musical instrument convertible between fretted and fretless playing configurations that includes: a body; a neck, the neck being connected to the body at one of its ends; a fingerboard disposed on the neck; a plurality of movable frets spaced apart at positions along the fingerboard; a plurality of strings disposed above the frets; and a fret adjustment device for adjusting the positions of the plurality of frets within respective fret slots in the fingerboard, the fret adjustment device including a metallic component and at least one strip of material located adjacent to the metallic component. In this embodiment, the at least one strip of material separates the metallic component of the fret adjustment device from another component of the instrument that is formed from metal. Also, in this embodiment, the at least one strip of material is configured to provide permanent dry lubrication for the metallic component of the fret adjustment device. 
         [0034]    In a preferred embodiment of this aspect of the present invention, the at least one strip of material is formed from a polymer. 
         [0035]    In another preferred embodiment, the metallic component of the fret adjustment device is a cam rod. 
         [0036]    In yet another preferred embodiment, the other component of the instrument that is formed from metal is a fret. 
         [0037]    In still another preferred embodiment, an additional strip of material is provided between the metallic component of the fret adjustment device and the neck. In yet another preferred embodiment, the at least one strip of material and the additional strip of material are both formed from a polymer. 
         [0038]    In accordance with a third aspect of the present invention, there is provided a stringed musical instrument convertible between fretted and fretless playing configurations that includes: a body; a neck, the neck being connected to the body at one of its ends; a fingerboard disposed on the neck; a plurality of movable frets spaced apart at positions along the fingerboard; a plurality of strings disposed above the frets; and a fret adjustment device for adjusting the positions of the plurality of frets within respective fret slots in the fingerboard, the fret adjustment device including a plate member disposed in the body of the instrument and at least one cam rod extending beneath the plurality of frets, the plate member having at least one aperture disposed therein. In this embodiment, the at least one aperture of the plate member forms a passive connection with one end of the at least one cam rod. 
         [0039]    In a preferred embodiment of this aspect of the present invention, the plate member is formed from a polymer. In another preferred embodiment, the plate member is rectangular in shape. 
         [0040]    In yet another preferred embodiment, the at least one aperture of the plate member is in the form of a countersunk hole. In still another preferred embodiment, the at least one aperture of the plate member comprises an upper countersink portion and a lower countersink portion. 
         [0041]    In yet another preferred embodiment, the at least one aperture of the plate member comprises a plurality of apertures in the plate member and the at least one cam rod comprises a plurality of cam rods, whereby each of the plurality of apertures in the plate member forms a passive connection with a respective end of one of the plurality of cam rods. 
         [0042]    In still another preferred embodiment, the at least one cam rod is bent at a substantially 90 degree angle, thereby creating a short portion of the at least one cam rod and a long portion of the at least one cam rod. In this preferred embodiment, an end of the short portion of the at least one cam rod forms a passive connection with the at least one aperture of the plate member. 
         [0043]    In yet another preferred embodiment, the plurality of movable frets includes a last fret at an end of the fingerboard nearest to the body. In this preferred embodiment, bending the at least one cam rod at the substantially 90 degree angle enables a spacing distance between the last fret and the end of the fingerboard to not be substantially greater than the distances between the other frets of the plurality of movable frets. 
         [0044]    In still another preferred embodiment, the at least one cam rod is cut or ground flat along a substantial portion of its length, thereby forming a substantially flat side extending in a longitudinal direction of the at least one cam rod. In yet another preferred embodiment, the at least one cam rod has two substantially flat, opposed sides extending in a longitudinal direction along its length. In still another preferred embodiment, the two substantially flat, opposed sides of the at least one cam rod are substantially parallel to one another. 
         [0045]    It is to be understood that the foregoing objects and summary, and the following detailed description of the present invention, are merely exemplary and explanatory in nature. As such, the foregoing general description and the following detailed description of the invention should not be construed to limit the scope of the appended claims in any sense. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0046]    The invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0047]      FIG. 1  is a top view of the convertible stringed musical instrument according to an embodiment of the invention; 
           [0048]      FIG. 2  is an exploded, partial perspective view of the convertible stringed musical instrument according to an embodiment of the invention; 
           [0049]      FIG. 3  is an exploded, partial perspective view of the neck and fingerboard portion of the convertible stringed musical instrument according to an embodiment of the invention; 
           [0050]      FIG. 4  is a sectional end view of the body of the convertible stringed musical instrument according to an embodiment of the invention cut along the cutting-plane line A-A in  FIG. 1 ; 
           [0051]      FIG. 5   a  is a partial longitudinal sectional view of the neck and fingerboard portion of the convertible stringed musical instrument according to an embodiment of the invention, which is cut along the cutting-plane line B-B in  FIG. 1 , and depicts the frets in a raised position; 
           [0052]      FIG. 5   b  is a partial longitudinal sectional view of the neck and fingerboard portion of the convertible stringed musical instrument according to an embodiment of the invention, which is cut along the cutting-plane line B-B in  FIG. 1 , and depicts the frets in a lowered position; 
           [0053]      FIG. 6   a  is an enlarged view of the cam rod ends of the convertible stringed musical instrument according to an embodiment of the invention with a fret being depicted in a raised position; 
           [0054]      FIG. 6   b  is an enlarged view of the cam rod ends of the convertible stringed musical instrument according to an embodiment of the invention with a fret being depicted in a lowered position; and 
           [0055]      FIG. 7  is an enlarged sectional view of the fingerboard of the convertible stringed musical instrument according to an embodiment of the invention. 
       
    
    
       [0056]    Throughout the figures, the same parts are always denoted using the same reference characters so that, as a general rule, they will only be described once. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0057]    An embodiment of the inventive convertible stringed musical instrument is seen generally at  10  in  FIG. 1 . The convertible stringed musical instrument  10  generally comprises a body  18 , a neck  20  affixed to the body  18  at its first end, a fingerboard  34  disposed on the top portion of the neck  20 , and a headstock  60  affixed to the second end of the neck  20 . As shown in  FIG. 1 , the exemplary body  18  includes a finger grasping portion  12  for actuating the fret adjustment device of the present invention, a bridge  68 , a plurality of pickups  72 , and adjustment knobs  70  for controlling operational parameters of the instrument  10 , such as its volume and tone. The fingerboard  34  comprises a plurality of frets  44  spaced along the length thereof, a nut  64  disposed adjacent to the headstock  60 , and a plurality of strings  66  extending along the length of the fingerboard  34  and disposed above the frets  44 . Also, as depicted in  FIG. 1 , the headstock  60  includes a plurality of tuning pegs  62  disposed on opposed sides thereof. However, it is to be understood that the convertible stringed musical instrument  10  shown in  FIG. 1  is merely exemplary in nature, and is no way intended to limit the scope of the claimed invention. For example, the claimed invention is equally applicable to stringed musical instruments that do not contain a headstock with tuning pegs (i.e., an instrument of the headless neck variety). In such a headless neck type instrument, the tuning mechanisms are located as part of the bridge or behind a bridge. Moreover, it is to be understood that the fret adjustment device of the present invention is not limited to one particular type of stringed musical instrument. Rather, it can be readily used on basses, acoustic guitars, electric guitars, banjos, etc. The primary components of the fret adjustment device of the musical instrument  10  will be described in detail below. 
         [0058]    Advantageously, the fret adjustment device of the present invention contains no gears, no welded parts, no rivets, no metal castings, and no metal springs to rattle or break. In addition, the design of the inventive fret adjustment device allows conventional tension rod systems to be used for adjusting the curvature of the neck  20 . 
         [0059]    Referring to the preferred embodiment of  FIG. 2 , the body  18  is detachably connected to the neck  20  of the instrument  10  by virtue of a plurality of screws passing through a plurality of corresponding holes  24  in the body  18 . This detachable configuration of the musical instrument  10  greatly facilitates the servicing thereof. 
         [0060]    Also, as shown in  FIG. 2 , the actuator mechanism of the invention comprises a finger grasping portion  12  that is attached to a plate portion  14 . As best seen in  FIG. 4 , the plate portion  14  slides within a slot  16  in the body  18  of the convertible stringed musical instrument  10 . In a preferred embodiment of the invention, the plate portion  14  is formed from a polymer and has a generally rectangular geometry with rounded ends. However, it is to be understood that the plate portion  14  could be formed from another material (e.g., a composite), and also could be formed using other geometric shapes without departing from the spirit of the invention. 
         [0061]    In one embodiment of the invention, the finger grasping portion  12  of the actuator mechanism is attached to the plate portion  14  via a screw  22  (see  FIG. 4 ). However, one of ordinary skill in the art will readily appreciate that finger grasping portion  12  of the actuator mechanism can be affixed to the plate portion  14  using other alternative attachment means and mounting arrangements (e.g., the screw  22  could be arranged in a different position or a plurality of screws  22  could be used). Moreover, one of ordinary skill in the art will readily appreciate that the finger grasping portion  12  of the actuator mechanism could be integrally formed with the plate portion  14 , thereby obviating the need for any attachment means at all. Furthermore, it is to be understood that parts other than the finger grasping portion  12  could be connected to the plate portion  14  in order to effectuate its back-and-forth movement. For example, rather than the finger grasping portion  12 , a rotatable lever could be utilized in order to move the plate portion  14  back-and-forth (see e.g., sheet 13 of 14, FIGS. 11 and 12, in U.S. Provisional Patent Application No. 61/341,325, which is herein incorporated by reference in its entirety). 
         [0062]    The finger grasping portion  12  and plate portion  14  is located in close proximity to the end of the neck  20  so that a musician can quickly and easily switch the instrument  10  between fretted and fretless modes during the normal playing of the instrument  10 . Also, because a musician can simply actuate the fret adjustment device using the finger grasping portion  12 , no tools are needed to switch the instrument  10  between fretted and fretless playing configurations. In addition, due to the unobtrusive integration of the components into the instrument body  18 , the finger grasping portion  12  and plate portion  14  in no way interferes with the normal playing style. 
         [0063]    Now, referring to  FIG. 4 , it can be seen that the plate portion  14  of the actuator mechanism is slidably disposed within the slot  16  of the body  18 . In order to accommodate the plate portion  14  and to facilitate a compact arrangement of the parts, the end of the neck  20  is desirably provided with a notch  26  therein (see  FIGS. 2 and 3 ). The plate portion  14  is provided with plurality of apertures  28  disposed therethrough for enabling the bent end portions of cam rods  30  to passively connect with the plate portion  14  by sliding through the apertures  28 . The dash-dot lines in  FIGS. 2 and 3  symbolically represent how the end portions of cam rods  30  fit together with the apertures  28  in plate portion  14 . In a preferred embodiment of the invention, the plurality of apertures  28  are in the form of a countersunk hole, which includes an upper countersink portion  28   a  and a lower countersink portion  28   b , in order to achieve the desired movement of the end portions of the cam rods  30  within the apertures  28 . In other embodiments, rather than having an upper countersink portion  28   a  and a lower countersink portion  28   b , the plurality of apertures  28  are formed using a single countersink that continually extends from the top surface of the plate portion  14  to the bottom surface of the plate portion  14 . In still other embodiments, rather than being provided as countersunk holes, the plurality of apertures  28  are in the form of elongated slots that taper inwardly as they extend from the top surface of the plate portion  14  to the bottom surface of the plate portion  14 . 
         [0064]    The term “passive connection” is generally used herein to refer to an interlocking arrangement between components that enables the components to be operatively coupled with one another such that the movement of one component will bring about a consequential movement of the other component, but does not require the components to be positively attached to one another. Thus, in the particular context of this invention, there is desirably a passive connection between the bent end portions of the cam rods  30  and the plate portion  14  by virtue of the bent end portions passing through the apertures  28 . While this passive connection enables the movement of the plate portion  14  (e.g., linear displacement) to bring about a consequential movement of the cam rods  30  (e.g., rotational movement), it does not require the plate portion  14  to be positively attached to the cam rods  30 . The passive connection between these two components  14 ,  30  is very beneficial because it enables the neck  20  to be easily detached from the body  18  so that the musical instrument  10  can be readily serviced. In particular, the neck  20  can be removed and reinstalled to the instrument body  18  in the same manner as a standard bolt-on neck system, which does not contain a fret adjustment system, by aligning the ends of the cam rods  30  with the apertures  28  in the plate portion  14 , and then installing the neck mounting screws (not shown) through holes  24  in instrument body  18 . Thus, the convertible nature of the stringed musical instrument  10  does not have any detrimental effects on the serviceability thereof. 
         [0065]    In addition, the passive connection between the bent end portions of the cam rods  30  and the plate portion  14  advantageously simplifies the manufacturing of the inventive fret adjustment device by obviating the need for the use of any geared coupling systems. Thus, because the present invention does not contain any gears at the end of the neck  20 , the manufacturing cost of the convertible stringed musical instrument  10  is decreased. 
         [0066]    Referring to  FIGS. 3 and 4 , it can be seen that there is an adjustable truss rod  74  disposed in a central portion of the neck  20 . The truss rod  74  adjusts the lengthwise curvature of the neck  20 . Advantageously, the fret adjustment device of the present invention allows a conventional tension rod system to be used for the overall adjustment of the curvature of neck  20 . 
         [0067]    As best depicted in  FIG. 3 , the ends of the cam rods  30  are preferably bent at a substantially 90 degree angle with respect to their longitudinal axes, thereby creating a long portion  30   a  and a short portion  30   b  of each cam rod  30 . The long portion  30   a  of each cam rod  30  extends longitudinally through a respective neck slot  32  over the length of the fingerboard  34 , or substantially over the length of the fingerboard  34  (see  FIG. 3 ). The long portion  30   a  of each cam rod  30  is rotatably disposed within a respective neck slot  32  about a respective longitudinal pivot axis. As shown in  FIG. 3 , the short portion  30   b  of each cam rod  30  is rotatably disposed within a respective triangular-shaped groove  58  that is cut into the end of the neck  20 . In a preferred embodiment, the two angled sides  58   a  of each groove  58  form an approximately 60 degree angle with one another (the imaginary vertex is disposed near the upper surface of the neck  20 ). Although, in other embodiments, the angle between the two angled sides  58   a  of each groove  58  could greater or less than approximately 60 degrees. Because the short portion  30   b  of each cam rod  30  extends below the bottom surface of the plate portion  14  (see  FIG. 4 ), a cam rod clearance slot  76  is provided in the body  18 . The cam rod clearance slot  76  is disposed below the slot  16  and its top is open thereto. 
         [0068]    In a preferred embodiment of the invention, the bent design of the cam rods  30  advantageously allows the spacing distance  78  between the last fret  44  at the end of the fingerboard  34  nearest to the body  18  to not be substantially greater than any of the distances between the other frets  44  that are longitudinally spaced along the fingerboard  34  (see  FIG. 1 ). Because the spacing distance between the last fret  44  and the end of the fingerboard  34  is minimized, the fret adjustment device of the present invention does not interfere with right hand playing styles. 
         [0069]    Now, turning to  FIGS. 6   a  and  6   b , it can be seen that the long portion  30   a  of each cam rod  30  is cut or ground flat along the length thereof to allow them to operate as lifting cams. Thus, after being cut or ground flat, the long portion  30   a  of each cam rod  30  contains at least one substantially flat side  30   s  that extends continuously along its entire length or substantially its entire length. 
         [0070]    As depicted in  FIGS. 3 ,  6   a , and  6   b , there is at least one narrow strip of material  36  above and below the long portion  30   a  of each cam rod  30 . Even though the figures only show a single strip of material  36  above and below the long portion  30   a  of each cam rod  30 , the invention explicitly contemplates the possible use of more than one strip of material  36  above and below the long portion  30   a  of each cam rod  30 . In a preferred embodiment, these narrow strips of material  36  are formed from a polymeric material. However, it is to be understood that other materials with similar properties can be used without departing from the spirit of the invention, such as composites. 
         [0071]    In a preferred embodiment of the invention, the fingerboard  34  is glued onto the upper surface of the neck  20 . Although, in other embodiments, the fingerboard  34  could be affixed to the upper surface of the neck  20  using other attachment means such as, but not limited to, screws or other suitable fasteners. 
         [0072]    The fingerboard  34  comprises a plurality of elongated fingerboard slots  38  disposed along the length thereof (see  FIG. 3 ). The upper side of each fingerboard slot  38  is provided with series of successive curved grooves  38   a , thereby giving the upper surface of each fingerboard slot  38  a scalloped appearance (see  FIG. 5   b ). The fingerboard slots  38  are machined so as to substantially align with the neck slots  32  in the neck  20 . Also, the neck slots  32  and the fingerboard slots  38  with curved grooves  38   a  are machined prior to the neck  20  and the fingerboard  34  being glued together. Each of the successive curved grooves  38   a  on the upper side of each fingerboard slot  38  is cut so that it is substantially centered on each fret slot  42  (see  FIGS. 5   b  and  7 ). 
         [0073]    Fret slots  42  are cut at the appropriate locations so as to open the interface between the fret slots  42  and the fingerboard slots  38 . Frets  44  are contained within the fret slots  42  by means of a slip-fit engagement therebetween. The side-to-side movement of the frets  44  is restricted by the fingerboard binding  46  (see  FIGS. 3 and 4 ). 
         [0074]    As best shown in  FIG. 3 , each fret  44  is provided with a plurality of longitudinally extending rods  50  extending therethrough. The longitudinally extending rods  50  pass through apertures  48 , which are spaced apart from one another on each fret  44 . The longitudinally extending rods  50  retain the frets  44  in the fingerboard  34  and additionally serve as springs in the fret adjustment system of the musical instrument  10 . Each longitudinally extending rod  50  extends substantially over the entire length of the fingerboard  34 . In a preferred embodiment of the invention, each longitudinally extending rod  50  is formed from a polymeric material. Using polymer rods  50  is advantageous because (a) it reduces the cost of the fret adjustment device by employing a simple, inexpensive material, (b) it minimizes metal-to-metal vibration rattles, (c) it permits the rods  50  to be easily replaced when required, and (d) it eliminates a large number of parts and/or the riveting, welding, or complex machining of parts that could be required when other materials are selected. However, while polymer is the preferred material, it is to be understood that each longitudinally extending rod  50  could be formed from another material (e.g., a composite) with similar properties. 
         [0075]    Also, as shown in  FIG. 3 , an end cap  40  is provided over the end of the neck  20  and the fingerboard  34 . The end cap  40  is preferably affixed to the neck  20  by means of screws  52  that extend through holes  56  in end cap  40  and holes  54  in neck  20 . It is advantageous to utilize a fastening means that can be easily removed when a component of the fret adjustment device needs to be repaired or replaced, such as the screws  52 , which are depicted in  FIG. 3 . 
         [0076]    Now, to better illustrate the functionality of the invention, the operation of the fret adjustment system of the musical instrument  10  will be explained. The inventive fret adjustment system is designed to be easily utilized by a musician while he or she is playing a musical composition on the instrument  10 . The functionality of the fret adjustment system will be initially explained for the situation in which the frets are raised by the musician so as to enable the fretted configuration of the musical instrument  10 . 
         [0077]    First, the musician grasps the finger grasping portion  12  and moves it in a linear fashion away from the end of the neck  20 . Because the plate portion  14  is affixed to the finger grasping portion  12 , the plate portion  14  is also slidingly displaced in the same direction as the finger grasping portion  12 . The sliding action of the plate portion  14  rotates the bent end portions of the cam rods  30  through an approximately 60 degree arc A 1  (see the solid-line positions in  FIG. 4 ). The angular displacement of the bent end portions of the cam rods  30  is made possible by virtue of the apertures  28  in the plate portion  14 , which preferably each have an upper countersink portion  28   a  and a lower countersink portion  28   b . As described above, the apertures  28  with upper countersink portion  28   a  and lower countersink portion  28   b  form a passive sliding connection between the plate portion  14  and the cam rods  30 . 
         [0078]    As explained above, the long portion  30   a  of each cam rod  30  has at least one narrow strip of material  36  inserted above and below it that runs substantially the full length of the fingerboard  34 . In a preferred embodiment, these strips of material  36  are formed using a polymer. When the bent end portions of the cam rods  30  are actuated through their approximately 60 degree arc A 1 , the long portions  30   a  of cam rods  30  are naturally rotated in the same manner. As they are rotated, the long portions  30   a  of cam rods  30  push up against the upper strips of material  36   a  (see  FIG. 6   a ). Because the bottom edges of frets  44  are disposed on the top surfaces of the upper strips of material  36   a , the upward displacement of the strips of material  36   a  result in a corresponding upward displacement of the frets  44 . Thus, the top portion of each fret  44  is raised to a desired height above the fingerboard  34 . As best shown in  FIGS. 6   a  and  6   b , the lower strips of material  36   b  are sandwiched between the cam rods  30  and the bottom surface of the neck slot  32 . 
         [0079]    As previously discussed, the frets  44  are retained in the fingerboard  34  by a slip-fit connection between the frets  44  and the fret slots  42 , as well as between the frets  44  and the fingerboard binding  46 . The longitudinally extending rods  50  (see  FIG. 3 ), which hold the frets  44  in the fret slots  42 , also function as return springs that pull frets  44  downward when the finger grasping portion  12  and the plate portion  14  attached thereto is moved towards the end of the neck  20 . 
         [0080]    When the frets  44  are in the raised position, the successive curved grooves  38   a  (scalloped-shaped cuts), which are provided on the upper side of each fingerboard slot  38 , allow space for the longitudinally extending rods  50  to elastically deform (see  FIGS. 5   a  and  7 ). The successive curved grooves  38   a  (scalloped-shaped cuts) are of approximately equal size so as to enable each fret  44  to be under the same spring tension. 
         [0081]    Next, the functionality of the fret adjustment system will be described for the situation in which the frets are lowered by the musician so as to enable the frettless configuration of the musical instrument  10 . 
         [0082]    When the musician grasps the finger grasping portion  12  and moves it in a linear fashion towards the end of the neck  20 , the plate portion  14  is also slidingly displaced in the same direction, and the bent end portions of the cam rods  30  are rotated through an approximately 60 degree arc A 2  (see the dashed-line positions in  FIG. 4 ). The long portions  30   a  of cam rods  30  are naturally rotated through the same approximately 60 degree arc A 2  as the bent ends portions. As they are rotated, the at least one flat side  30   s  of each long portion  30   a  of each cam rod  30  assumes a position that is substantially parallel to the bottom surface of the adjacent upper strip of material  36   a  (see  FIG. 6   b ). Then, the spring force of the longitudinally extending rods  50  urges the frets  44  to their lowered positions as the longitudinally extending rods  50  assume their substantially straight, substantially undeformed configuration (see FIG.  5   b ). In their lowered position, the top edge of each fret  44  is substantially flush with the top surface of the fingerboard  34 . 
         [0083]    Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is apparent that this invention can be embodied in many different forms and that many other modifications and variations are possible without departing from the spirit and scope of this invention. For example, even though two cam rods  30  are explained in conjunction with the embodiment described above, it is to be understood that more than two cam rods  30  can be used in necks that are wider than the standard neck width, such as the necks of five and six string basses. Moreover, as another example, the rise height of the frets  44  can be modified by changing the dimension of the ground-off flat sides  30   s  of cam rods  30  and/or the diameter of cam-rods  30 . Thus, the cam rods  30  are not limited to any specific shape. 
         [0084]    While exemplary embodiments have been described herein, one of ordinary skill in the art will readily appreciate that the exemplary embodiments set forth above are merely illustrative in nature and should not be construed as to limit the claims in any manner. Rather, the scope of the invention is defined only by the appended claims and their equivalents, and not, by the preceding description.