Abstract:
The present invention provides in combination, an intonated string nut and striun locking mechanism for a musical string instrument with a fretted fingerboard where the combination intonated string nut and string locking mechanism includes a string nut fulcrum and a string locking means, where each string nut fulcrum may have a varying linear position in relation to each individual string in order to provide the optimum compensation amount for improviun the consistency and production of in-tune musical notes during play for musical string instruments with fretted fingerboards.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to musical string instruments with fretted fingerboards, and more specifically to an improved nut mechanism that incorporates a string length intonation adjustment means and a means for rigidly securing the strings in position in order to ensure tuning stability. 
       THE PRIOR ART 
       [0002]    It is well known in the art that stringed musical instruments with fretted fingerboards require specific string length and string height adjustments at the bridge and at the nut fulcrum points in order for the instrument to play in tune, and also be comfortable to play. String intonation is the technique wherein the theoretical length of a string is elongated in order to compensate for the increase in pitch that naturally occurs due to an increase in a string&#39;s tension as it is deflected away from its resting position and towards the fingerboard for contact. This “compensation” allows the musical notes produced by varying a string&#39;s vibrating length at specific frets along the fingerboard to be in tune relative to each other. 
         [0003]    Throughout most of the history of fretted string instrument manufacture, this compensation was only done at the bridge fulcrum point. During the final adjustment phase of instrument production, a luthier would pluck the string, and at a point located precisely half way between the nut and the bridge, the luthier would then lightly touch the string thereby producing the first harmonic of the open string, with that note being an octave above pitch of the open string. The luthier would then deflect the string to the twelfth fret, located precisely at one half of the string&#39;s theoretical length, and pluck it in order to produce the fretted octave note of the open string. He would then compare these harmonic octave notes and fretted octave notes repeatedly while adjusting the position of the string&#39;s bridge fulcrum point away from the nut until the harmonic and fretted notes of the string being adjusted were identical. 
         [0004]    Unfortunately, this technique only works in regards to fretted notes. When one compares the relationship between an instrument&#39;s fretted notes, and its open string notes wherein a string is simply plucked and allowed to vibrate between its bridge and nut fulcrum points, the ideal theoretical relationship between open string frequencies and fretted string frequencies does not exist. This is because vibrating open strings are not deflected towards the fingerboard, and therefore they do not require any compensation. The open string notes will therefore be lower in frequency in relationship to the fretted notes than they should be. With this, if a player tunes his instrument to its open string notes, the only fretted note that will be in ideal relative tune with the open string&#39;s pitch will be the fretted note produced at the 12 th  fret. The fretted notes above the 12 th  fret will go progressively flat as you move towards the bridge, and the fretted notes below the 12 th  fret will go progressively sharp as you move towards the nut. A means must be used to restore the ideal relationship between open string and fretted note frequencies. 
         [0005]    In an attempt to correct this difficulty and allow both open stings notes and fretted notes to be in relative tune with each other, the idea of additionally compensating a string&#39;s length at the nut in order to restore the ideal ratio between open string and fretted note frequencies has found its way into the art. Non-adjustable examples of this concept can be found in U.S. Pat. No. 4,295,404, U.S. Pat. No. 6,156,962, and U.S. Pat. No. 6,433,264. And adjustable example of a compensated string nut can be found in U.S. Pat. No. 5,750,910. 
         [0006]    Furthermore, additional difficulties in keeping the instrument in proper tune arise with the usage of vibrato mechanisms. These mechanisms allow the player to vary the tension of the strings during play in order to produce a wide range of frequency related effects, most notably vibrato, which is a periodic change in a string&#39;s frequency. These mechanisms are difficult to use in that the return of a string to its original tension is very difficult to achieve because these mechanisms typically use springs for their restoring force. Changes in temperature, friction of a string&#39;s contact points at the bridge and nut, the stability of a string&#39;s material, and variations in the holding position of a string&#39;s tuning mechanism as a string&#39;s tension changes during vibrato mechanism usage all combine to make the tuning and stability of string tensions during play very difficult to achieve. 
         [0007]    There are a variety of mechanisms within the art that provide the player with a means for eliminating string slippage at the nut in order to improve the tuning stability of the instrument. With each mechanism, the player rigidly secures a length of each string between two flat surfaces. U.S. Pat. No. 4,517,874, U.S. Pat. No. Des. 280,330, and U.S. Pat. No. 4,475,432 show string locking mechanisms that require the usage of an allen wrench to secure the string between two flat surfaces. U.S. Pat. No. 4,574,678, U.S. Pat. No. 4,667,561, U.S. Pat. No. 4,669,350, U.S. Pat. No. 5,932,822, and U.S. Pat. No. Re. 32,863 each illustrate string locking mechanisms that can be engaged manually by the player without the need for using a tool. Any of these locking mechanisms can be used with the present invention. 
       OBJECTS AND ADVANTAGES 
       [0008]    Musical note production during play and the art of musical string instrument design find advancement with the mechanical format of the present invention. The primary object of the present invention is to provide the player with a combination intonated string nut and string locking mechanism as a means for providing for the production of musical notes that are more precisely in-tune during play, and to provide for a more exacting return of string tensions to their proper levels after the usage of a vibrato mechanism for frequency related effects has been engaged. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  Perspective view of the present invention 
           [0010]      FIG. 2  Exploded perspective view of the present invention 
           [0011]      FIG. 3  Front view of the main plate of the present invention. 
           [0012]      FIG. 4  Top view of the main plate of the present invention. 
           [0013]      FIG. 5  Exploded side view of present invention 
           [0014]      FIG. 6  Assembled side view of the present invention 
           [0015]      FIG. 7  Assembled top view of the present invention 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring now to the drawings,  FIG. 1  illustrates a partial view of a guitar&#39;s neck  10 , fingerboard  20 , frets  30 , headstock  40 , machine heads  50 , strings  60 , and the combination intonated string nut and string locking mechanism of the present invention  100 . 
         [0017]      FIG. 2  illustrates a perspective exploded view of the preferred embodiment of the present invention  100 . As can be seen, the present invention  100  includes base plate  110 , string locking plate channel  120 , string locking plates  130  that include string locking plate slip fit through holes  135 , string locking plate bolts  140 , string locking plate threaded holes  150 , front elongated v-shaped string guides  160 , string intonation cutouts  170  with intonated string nut fulcrums  175 , and rear elongated v-shaped string guides  180 , string nut securing thread holes  190 , and string nut securing bolts  200 . Through-neck, counter-bored, slip-fit holes  210  with boss&#39;  220  within neck  10  is a common feature used by guitar manufacturers. 
         [0018]    By placing the present invention  100  in position above through-neck counter-bored slip-fit holes  210  wherein string nut securing thread holes  190  are in alignment with said through-neck slip-fit counter-bored holes  210 , and then by placing string nut securing bolts  200  within said through-neck slip-fit counter-bored holes  210 , and rotating said string nut securing bolts  200  until they engage with and are rigidly torqued against the threads of string nut securing thread holes  190  and boss  220  of said through-neck counter-bored slip-fit holes  210 , the present invention  100  finds rigid position securement on the instrument at the proper location between fingerboard  20  and headstock  40  on neck  10 . 
         [0019]    Front elongated v-shaped string guides  160 , intonation cutouts  170  with intonated string nut fulcrums  175 , and rear elongated v-shaped string guides  180  provide the means for guiding and positioning the strings  60  in the proper location while also providing the means for supplying the additional compensated string length required for the open string notes and the fretted string notes to stay in relative tune with each other during play. The elongated v-shape of each front elongated v-shaped string guide  160  and rear elongated v-shaped string guide  180  helps to aid in the initial attachment and final positioning of the string. The side of each string guide provides a surface for the string to follow to its final position located in the bottom center where the intonated string nut fulcrums  175  are located. 
         [0020]      FIG. 3  shows a front view of base plate  110 . As can be seen, front elongated v-shaped string guides  160 , string intonation cutouts  170 , and the fronts of the intonated string nut fulcrums  175  are shown. In the manufacturing process, a small endmill was used to fabricate the string intonation cutouts  170 , and the depth of each of the intonated string nut fulcrums  175  in a single plunging operation. The circular shape of each of the string intonation cutouts  170  was found to be very beneficial in that a minimum of material needed be removed, and it provides for a smooth top edge of the front of base plate  110  thereby eliminating any potential for accidental damage to the player&#39;s hand. 
         [0021]    A top view of base plate  110  is shown in  FIG. 4 . This figure clearly shows the varying depths of each of the string intonation cutouts  170  relative to the front face  110   a , and therefore the varying linear position of each string&#39;s intonated string nut fulcrum  175  thereby providing for the desired amount of compensation for each string. As can be appreciated, the ideal compensated length amount for each string will vary with the overall scale length of the instrument, and with the diameter and type of strings chosen by the player. String locking plate channel  120 , String locking plate thread holes  150 , rear elongated v-shaped string guides  180 , and string nut securing thread holes  190  are also shown. 
         [0022]    In  FIG. 5 , an exploded side view of the present invention is shown. Dashed lines  170   c  and  175   f  illustrate the configuration of string intonation cutouts  170 , and intonated string nut fulcrums  175 . Dashed line  180   r  illustrates the bottom face of rear elongated v-shaped string guide  180 . By slipping string locking plate bolt  140  through string locking plate slip fit through hole  135  of string locking plate  130 , aligning it with string locking plate threaded hole  150  and rotating it until the bottom surface of the head of string locking plate bolt  140  is in contact with the top of string locking plate  130  and the threads of string locking plate bolts  140  are securely torqued against the complementary mating threads of string locking plate threaded holes  150  by means of a wrench, each string will be compressed and rigidly held in position between the fixed surface at the bottom of s string locking plate channel  120  and the bottom face of string lock  130  thereby providing for an improvement in string tension stability especially when used in combination with a vibrato mechanism. 
         [0023]      FIG. 6  illustrates an assembled side view of the present invention. As can be seen by the dashed line  170   c , string intonation cutout  170  provides relief below string  60 , and the bottom of string  60  is in contact with intonated string nut fulcrum illustrated by dashed line  175   f . It can also be seen that the depth of string intonation cutout  170  determines the linear position of the front of intonated string nut fulcrum  175 , and therefore the amount of intonation provided to each string  60 . The locking feature of the present invention is also clearly indicated. As is seen, a portion of each string  60  is rigidly compressed between the bottom of string locking plate channel  120  and the bottom of string locking plate  130 . 
         [0024]    A top view of the present invention fully assembled is seen in  FIG. 7 . As is clearly seen, each string is provided a specific amount of compensation, and each is rigidly locked into linear position by means of compressing each string between a fixed surface and a variable height surface.