Stringed instrument having slidable saddles

A stringed instrument, such as a guitar is provided. The stringed instrument may include a tuning system in which harmonic and pitch tuning are simultaneously obtained. A bridge assembly is provided on the stringed instrument which includes a force conversion assembly capable of converting nonlongitudinal forces into longitudinal forces such that selective adjustment of a tuning knob or similar control by a user results in slidable movement of saddle members.

 

I claim:

1. A stringed instrument comprising:

a body;

a neck including a first end attached to said body, and a second end remote from said body;

a nut assembly connected to said neck at said second end;

a bridge assembly mounted on said body; and

a plurality of strings extending between said nut and bridge assemblies, said bridge assembly including a plurality of saddles and a force conversion assembly constructed and arranged to convert a nonlongitudinal force applied by a user during tuning of said strings to a longitudinal force whereby at least one of said saddles is forced to slide toward or away from said nut assembly, said force conversion assembly including a rotatable tuning knob and a plurality of lever arms operatively connected to each of said plurality of saddles.

2. The stringed instrument of claim 1 wherein said rotatable tuning knob comprises a cylindrical head attached to a threaded shaft.

3. The stringed instrument of claim 2 wherein said force conversion assembly further comprises a riser having a threaded passageway arranged for threadable movement along said threaded shaft.

4. The stringed instrument of claim 1 further comprising a fretboard arranged on said neck.

5. The stringed instrument of claim 1 wherein said nut assembly comprises a plurality of string holder cavities and a plurality of corresponding nut critical contact surfaces.

6. The stringed instrument of claim 5 wherein said bridge assembly further comprises a plurality of bridge critical contact surfaces.

7. The stringed instrument of claim 6 wherein each of said plurality of strings includes a first anchor connected to a first end thereof, and a second anchor connected to a second end thereof, said first anchor being arranged within one of said saddles of said bridge assembly, said second anchor being arranged within a corresponding one of said string holder cavities of said nut assembly.

8. A stringed instrument comprising:

a body;

a neck including a first end attached to said body, and a second end remote from said body;

a nut assembly connected to said neck at said second end;

a bridge assembly mounted on said body; and

a plurality of strings extending between said nut and bridge assemblies, said bridge assembly including a plurality of saddles and force conversion means for converting a nonlongitudinal force applied by a user during tuning of said strings into a longitudinal force to thereby effect slidable movement of at least one of said saddles toward or away from said nut assembly, said force conversation means including a rotatable tuning knob and a plurality of lever arms operatively connected to each of said plurality of saddles.

9. The stringed instrument of claim 8 wherein said rotatable tuning knob includes a threaded shaft, said stringed instrument further comprising a riser having a threaded passageway arranged for threadable movement along said threaded shaft.

10. The stringed instrument of claim 8 further comprising a fretboard arranged on said neck.

11. The stringed instrument of claim 8 wherein said nut assembly comprises a plurality of string holder cavities and a plurality of corresponding nut critical contact surfaces.

12. The stringed instrument of claim 11 wherein said bridge assembly comprises a plurality of bridge critical contact surfaces.

13. The stringed instrument of claim 12 wherein each of said plurality of strings includes a first anchor connected to a first end thereof, and a second anchor connected to a second end thereof, said first anchor being arranged within one of said saddles of said bridge assembly, said second anchor being arranged within a corresponding one of said string holder cavities of said nut assembly.

14. The stringed instrument of claim 10 wherein said plurality of lever arms of said bridge assembly are constructed and arranged such that rotation of one of said rotatable tuning knobs through a certain rotatable distance will cause a corresponding one of said plurality of saddles to slide a relatively small distance when the tension in a corresponding one of said strings is relatively high, and a relatively large distance when the tension in the corresponding one of said strings is relatively low.

15. A stringed instrument comprising:

a body;

a neck having a longitudinal axis along the length thereof, and including a first end attached to said body, and a second end remote from said body;

a nut assembly connected to said neck at said second end;

a bridge assembly mounted on said body; and

a plurality of strings extending between said nut and bridge assemblies substantially parallel to said longitudinal axis of said neck, said bridge assembly including a plurality of saddles, a plurality of lever arms operatively connected to each other and corresponding ones of said plurality of saddles, and a plurality of rotatable tuning knobs operatively connected to said plurality of lever arms such that a corresponding one of said plurality of saddles is forced to slide toward or away from said nut assembly along a plane substantially parallel to said longitudinal axis of said neck upon rotation of one of said tuning knobs.

16. The stringed instrument of claim 15 wherein said plurality of lever arms of said bridge assembly are constructed and arranged such that rotation of one of said rotatable tuning knobs through a certain rotatable distance will cause a corresponding one of said plurality of saddles to slide a relatively small distance when the tension in a corresponding one of said strings is relatively high, and a relatively large distance when the tension in the corresponding one of said strings is relatively low.

17. A bridge assembly for use with a stringed instrument, said stringed instrument having a body, a neck attached to said body, a nut assembly connected to said neck, said bridge assembly being mounted on said body of said stringed instrument, and a plurality of strings extending between said nut and bridge assemblies, said bridge assembly comprising:

a plurality of saddles and a force conversion assembly constructed and arranged to convert a nonlongitudinal force applied by a user during tuning of said strings to a longitudinal force whereby at least one of said saddles is forced to slide toward or away from said nut assembly, said force conversion assembly including a rotatable tuning knob and a plurality of lever arms operatively connected to each of said plurality of saddles.

18. The bridge assembly of claim 17 wherein said rotatable tuning knob comprises a cylindrical head attached to a threaded shaft.

19. The bridge assembly of claim 18 wherein said force conversion assembly further comprises a riser having a threaded passageway arranged for threadable movement along said threaded shaft of said tuning knob.

FIELD OF THE INVENTION

The present invention relates to stringed instruments, such as guitars and various components thereof.

BACKGROUND OF THE INVENTION

Inventors have expended great efforts over the years in their efforts to obtain an optimal tuning system for use with stringed musical instruments, such as guitars. These efforts are indicative of the need for improvement in this field. One particularly significant improvement was developed by the same inventor of the present invention and is disclosed in U.S. Pat. No. 5,705,760. The disclosure in the '760 patent includes, among other improvements, a "convergence" tuning system where harmonic tuning and pitch tuning can be simultaneously and easily obtained by a user of the guitar.

Standard guitars typically include six strings corresponding to the musical notes E, A, D, G, B and E. Guitar strings are placed under tension and extend at a substantially constant height above a fretboard mounted on the neck and the guitar body. In order to produce the sounds associated with the musical notes, the strings are placed in contact with two critical contact points. The first critical contact point is generally at the nut of the instrument, which is usually arranged on the guitar neck adjacent to the first fret of the fretboard. The second critical contact point is generally at the bridge of the instrument, which is provided on an opposing end of the fretboard on the body of the instrument. The strings are fixed at a distance beyond the critical contact points at the nut and bridge.

As is known to those skilled in the stringed instrument art the sound produced by the strings is affected by the harmonic length (i.e., the distance between where the strings contact the critical contact points at the nut and the bridge). Except for the guitar disclosed in the '760 patent, and in certain other patents obtained by the inventor herein, which have cumulative disclosures to the '760 patent, harmonic tuning of the strings has been a difficult process which needed to be performed by a professional. Harmonic tuning is accomplished by adjusting the distance between the critical contact points at the nut and bridge of the guitar.

The tension of the strings is a second factor which significantly affects the tone. String tension may be adjusted by tightening or loosening the string at the nut or bridge end of the guitar. Adjustment of the tension in the strings affects the pitch thereof and is commonly known as pitch tuning.

Except for the guitar disclosed in the '760 patent, and in certain other patents obtained by the inventor herein, which have cumulative disclosures to the '760 patent, prior art guitars required separate steps for pitch and harmonic tuning. For example, prior art tuning systems require each string of a guitar to be independently pitch and harmonically tuned by adjusting individual tension control elements while the distance between the critical contact points at the nut and the bridge are separately adjusted. In most prior art systems, proper harmonic and pitch tuning is obtained when strings ultimately reach a tuned state after many individual adjustments of separate tensioning and distance modifying controls.

Even in the improved guitar disclosed in the '760 patent, the bridge assembly does not include a force conversion device which converts nonlongitudinal forces (such as rotational, vertical and angular forces) into longitudinal forces to effect slidable movement of one or more saddle members arranged on a bridge assembly. The present invention addresses this need.

When using electric guitars, it is desirable to use pick-ups which include magneto-electro transducer elements designed to detect vibrations in associated guitar strings. Certain sophisticated guitar players demand the ability to adjust various aspects of their guitar including the arrangement of pick-ups with respect to the strings. Although prior art inventors have exerted efforts to create movable pick-up systems, all such prior art systems have drawbacks. No prior art system includes a mechanical control assembly, which allows a user to easily adjust the location of pick-ups to a desired position.

The prior art also fails to disclose or teach a guitar including a pick-up assembly having covers arranged on the guitar body over a slidable pick-up assembly and beneath associated strings where the cover extends substantially parallel to the surface of the guitar body.

Tremolos or vibratos are well known devices that are typically used with electric guitars to simultaneously and significantly either reduce or increase the tension of the strings of the guitar so that a desired variation in tone is obtained. Significant improvements in tremolo devices are disclosed in U.S. Pat. Nos. 4,171,661; 4,967,631; 4,497,236; and 4,882,967, all of which have been issued to the inventor of the present invention. Prior art tremolo systems typically include a raised tremolo arm which extends substantially above the surface of the guitar body. No prior art system discloses the use of a tremolo having a plate which extends substantially flush with the surface of the body of the guitar.

Another aspect of the present invention which is not disclosed in the prior art relates to a neck which is releasably and adjustably mounted on a guitar body. Sophisticated guitar players may wish to customize the action of the strings with respect to the fretboard for their own liking. This may involve adjusting the strings in any of three dimensions including the height of all of the strings on the fretboard, and the side-to-side alignment of the strings with respect to the fretboard (e.g., most guitar players prefer the strings to be centered on the fretboard, but with the low and high strings at different heights from the surface of the fretboard). Prior art guitars do not provide the user with the ability to customize the action of the strings based on a readily adjustable arrangement between the neck and the body, where the neck can be removed and replaced during travel and storage without modifying the previously customized setting.

There is also a need for a guitar, or other stringed instrument, which includes a modular headstock. While efforts have been made to develop readily removable and replaceable headstocks for guitars, the prior art fails to teach a system which includes removable head stocks where one headstock does not include tuning pegs, but the other head stock does.

The present invention addresses the shortcomings of the prior art by providing an improved stringed instrument, such as a guitar, which fills the foregoing needs.

SUMMARY OF THE INVENTION

The present invention overcomes the shortcomings of the aforementioned prior art guitars by providing a stringed instrument having an improved tuning system. The present invention is particularly directed toward a stringed instrument having a bridge assembly, which is adapted to convert nonlongitudinal forces (such as rotational, angular and vertical forces) to longitudinal forces whereby saddle members of the bridge assembly are caused to slide toward or away from a nut assembly of the stringed instrument.

In a preferred embodiment, the stringed instrument comprise a body, a neck including a first end attached to the body and a second end remote from the body. A nut assembly is preferably connected to the neck at the second end thereof and a bridge assembly is preferably mounted on the body spaced from the nut assembly. A plurality of strings extend between the bridge and nut assemblies, and may contact such assembles at nut and bridge critical contact surfaces. The bridge assembly preferably includes a plurality of saddles and a force conversion assembly, which is constructed and arranged to convert a nonlongitudinal force applied by a user during tuning of the guitar strings to a longitudinal force whereby at least one of the saddles is forced to slide toward or away from the nut assembly.

In a preferred embodiment, the force conversion assembly may comprise a rotatable tuning knob and a plurality of lever arms operatively connected to each of the plurality of saddles. In this preferred embodiment, rotation of one of the tuning knobs will cause movement of corresponding lever arms whereby the original rotational force is converted to angular and vertical forces extending along the lever arms. The forces are ultimately converted to a longitudinal force (e.g., parallel to the strings) which effects slidable movement of a corresponding saddle member. The rotatable tuning knob may comprise a cylindrical head attached to a threaded shaft.

The force conversion assembly may also comprise a riser having a threaded passageway therein where the riser is arranged for threadable movement along the threaded shaft. The riser is preferably mounted on a lever arm whereby threadable movement of the riser results in a change in the angular position of the lever arm.

Preferably, a fretboard is arranged on the neck of the stringed instrument. It is also preferable for the nut assembly to comprise a plurality of string holder cavities and a plurality of nut critical contact surfaces associated with each of the string holder cavities.

The bridge assembly of the present invention may also comprise a plurality of bridge critical contact surfaces which correspond on a one-to-one basis with the nut critical contact surfaces.

Each of the plurality of strings may include a first anchor connected to a first end thereof, and a second anchor connected to a second end thereof. The first anchor may be arranged within one of the saddles of the bridge assembly, and the second anchor may be arranged within a corresponding one of the string holder cavities of the nut assembly.

In accordance with another embodiment of the present invention, the stringed instrument may comprise force conversion means for converting a nonlongitudinal force into a longitudinal force whereby slidable movement of at least one of the saddles is effected toward or away from the nut assembly. As used herein, the term force conversion means is intended to cover various structural embodiments of a bridge assembly where a nonlongitudinal force initially applied by a user during tuning of the stringed instrument (such as the force applied when rotating a tuning knob) is converted into a longitudinal force so that an associated saddle slides toward or away from a corresponding nut critical contact surface.

In a preferred embodiment where the force conversion means comprises a plurality of lever arms and a plurality of corresponding rotatable knobs, it is desirable for the structure and arrangement of the force conversion device to be such that rotation of one of the rotatable tuning knobs through a certain rotatable distance will cause a corresponding one of the plurality of saddles to slide a relatively small distance when the tension in a corresponding one of the strings is relatively high, and a relatively large distance when the tension in the corresponding one of the strings is relatively low.

In accordance with another aspect of the present invention, a bridge assembly is provided per se for use with a stringed instrument. The bridge assembly preferably includes the force conversion assembly described above.

The above features and advantages of the present invention will be more fully understood with reference to the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a guitar including the features of the present invention.

FIG. 2 is an isolated perspective view of a portion of the guitar shown in FIG. 1 illustrating the tremolo plate in a depressed position.

FIG. 3 is an exploded perspective view of the bridge and tremolo assembly shown in FIG. 2.

FIG. 4 is an isolated assembled bottom perspective view of the bridge assembly shown in FIG. 3.

FIG. 5 is an isolated view of the convergence headstock and nut assembly portion of the guitar shown in FIG. 1.

FIG. 6 is a partially exploded view of the headstock with respect to the nut assembly and neck shown in FIG. 4.

FIG. 7 is an isolated perspective view of an alternate headstock in assembled position.

FIG. 8 is an enlarged isolated partially exploded view of the nut assembly and associated guitar strings shown in FIG. 4.

FIG. 9 is a partially exploded perspective view the neck and body of the present guitar.

FIG. 10 is a partially exploded view of the pick-up assembly and associated control mechanism of the present invention.

FIG. 11 is a cut away cross sectional view taken along line 11--11 of FIG. 1.

FIG. 12 is a cut away cross sectional view taken along line 12--12 of FIG. 1.

FIG. 13 is a schematic isolated view of a second embodiment of a pick-up assembly used in connection with the present guitar.

FIG. 14 is a cut away cross sectional view taken along line 14--14 of FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A guitar 20 in accordance with a first embodiment of the present invention is shown in FIG. 1. The guitar 20 may be an electric guitar. However, it should be appreciated that the present invention can be used in connection with various stringed instruments such as acoustic guitars, basses, violins, banjos and the like.

The guitar 20 includes a body 22 and a neck 24 secured to the body 22 at a first end thereof. A second end of the neck 24 is remote from the body 22 and is connected to a headstock 32. The neck 24 has a fretboard 26 mounted on the top surface. A nut assembly 28 is arranged between the second end of the neck 24 and the headstock 32 as shown in FIGS. 1, 5 and 8.

The nut assembly 28 includes a plurality of string holder cavities 30, each of which retain a bullet-shaped anchor 116 arranged at one end of corresponding guitar strings 114. This aspect of the present invention is also shown in FIGS. 1, 5 and 8.

A bridge assembly 34 is mounted on body 22 spaced from nut assembly 28 at the second end of the neck. Various aspects of the bridge assembly 34 are unique and will now be discussed.

As shown in FIGS. 2-4, the bridge assembly 34 includes a plurality of saddles 36 in which bullet-shaped anchors 118 of an end of guitar strings 114 are arranged. FIGS. 1, 5 and 8 also illustrate that each of the strings 114 include a pair of bullets at opposing ends. Bullet 116 is arranged at the "nut" end of the string and bullet 118 is arranged at the "bridge" end of the string. As noted above, and as used herein, the term "anchor" is intended to cover various types of objects which may be secured to one or both ends of an associated string for the purpose of facilitating fixation of the string with respect to the body and/or neck of the guitar. In a preferred embodiment, the anchor elements that are fixed to the ends of the string are bullet-shaped. The bullet-shaped anchor elements will be referred to herein as "bullets." In other embodiments, the anchor elements may comprise balls, blocks, pegs, and may be arranged in various other shapes and sizes.

In the embodiment shown in FIGS. 1-4, the bridge assembly 34 includes six slidable saddle members 36 which are used to retain six corresponding bullets 118 of guitar strings 114. These six strings 114 may correspond to the musical notes E, A, D, G, B and E, respectively. Guitar strings having bullet-shaped anchors arranged at both ends thereof secured in bridge saddle members and string holder cavities of a nut assembly are also disclosed in U.S. Pat. No. 5,705,760 which has been issued to Floyd D. Rose, the inventor of the present invention. The disclosure in the '760 patent is incorporated by reference herein.

The unique structure and operation of bridge assembly 34 is highly desirable when used in a stringed instrument, such as guitar 20 which includes a convergence tuning system. The term "convergence" as used herein refers to the substantially simultaneous occurrence of harmonic and pitch tuning of one or more strings of a guitar or other stringed instrument. This means that the string will simultaneously be harmonically tuned and pitch tuned upon performing a single adjustment which concurrently affects the string tension and the distance between a pair of critical contact surfaces on the associated instrument. The term "critical contact surface" is intended to designate the contact points on a guitar, or other stringed instrument, at which the strings are supported and between which the strings vibrate at a certain frequency so that a desired tone is obtained. The critical contact points typically exist at the nut and bridge of a guitar so that the distance between corresponding critical contact points at the nut and bridge define the harmonic length of an associated string. With respect to guitar 20, both the bridge assembly 34 and the nut assembly 128 includes critical contact surfaces between which the strings 114 vibrate.

The bridge assembly 34 includes a base 35 in which the slidable saddle members 36 are arranged. Each of the saddle members 36 include a bullet holding portion 38, which may be considered the true saddle portion of saddle members 36. As best shown in FIG. 2, bullet holding portions 36 include a hollow cavity having an opening 40 for receiving bullet 118 at an end of a corresponding string 114. The saddle members 36 also include a slot 42 open to the bullet holding cavity through which a corresponding string 114 extends when in assembled position. String 114 then contacts critical contact surface 44 at the proximal-most end of the saddle member 36.

Saddle member 36 also includes a central angled section 46 and a lower horizontally planar section 48. A downwardly extending vertical section 50 is arranged at the distal-most end of the lower planar section 48. As clearly shown in FIGS. 3 and 4, a roller 52 is pinned into assembled position at the juncture of lower horizontal section 48 and vertical section 50.

The bridge assembly 34 includes a unique force conversion assembly which performs the function of converting a nonlongitudinal force (e.g., a rotational, angular or vertical force) into a longitudinal force which effects slidable longitudinal movement of saddle member 36. In the embodiment shown in FIGS. 1-4, the force conversion assembly includes the combination of various levers, a tuning knob, and other components in combination with a portion of saddle member 36. The function of the force conversion assembly will be discussed below following a description of the structural components thereof, which include a small central lever arm 54 having an upper end 56 and a lower end 58. The upper end 56 includes a passageway (unnumbered) that is placed in alignment with passageways (unnumbered) near the bottom-most end of lower vertical section 50. A pin 60 (shown in the exploded view of FIG. 3) is used to secure the upper end 56 of small lever arm 54 to the downwardly extending vertical portion 50 of saddle member 56.

As also shown in FIGS. 3 and 4, a large lever arm 62 is arranged below small lever arm 54. The large lever arm 62 includes an upper end 64 which is adapted to be connected to the base 35 of bridge assembly 34 via elongated pin 68. Although the structure can change in alternate embodiments, in the illustrated embodiment a single elongated pin 68 may be used to secure the upper end 64 of each of the six lower lever arms 62 to the base 35 through a common passageway (not shown).

The lower end 66 of large lever arm 62 includes a forked portion for receiving the cylindrical end members 88 of riser 84. As best shown in FIG. 3, riser 84 includes a central threaded aperture 86. A central portion of lever arm 62 includes a pair of apertures (unnumbered) which are aligned with apertures (also unnumbered) at a lower end 58 of small lever arm 54. A pin 70 is placed through the aligned apertures to secure the lower end of lever arm 54 to the central portion of lever arm 62.

Large lever arm 62 includes a recessed portion 67 which is sized and shaped to receive the downwardly extending vertical portion 50 of saddle member 36 when the lever arm 62 is in its most horizontal position. This structure will be discussed further below in connection with the operation of the tuning system of the guitar 20.

A spring 72 is also secured by pin 70 at the lower end 58 of lever arm 54. The spring 72 will bias the lever arm 54 to an upward angular position with respect to lever arm 62.

Bridge assembly 34 includes a tuning screw 74 which is used for tuning guitar 20 and loading strings 114 therein as discussed further below. The tuning screw 74 includes a cylindrical head 76 and an elongated threaded shaft 78 which is arranged within threaded aperture 86 of riser 84. The cylindrical head 76 of tuning screw 74 is arranged within corresponding counter-bore 80 of bridge base 35 when in assembled position. In such position, threaded shaft 78 extends through central aperture 82 of the counter-bore 80.

A significant aspect of the present invention relates to the structure and operation of bridge assembly 34. In particular, slidable movement of a particular saddle 36 may be obtained by rotating the head 76 of a corresponding tuning screw 74. For example, as the head 76 of tuning screw 74 is rotated clockwise, it causes an associated saddle member 36 to slide away from the nut. Thus, the corresponding critical contact point 44 is moved away from the critical contact point at the nut assembly 28. Similarly, when head 76 of tuning screw 74 is rotated counterclockwise, the corresponding saddle 36 slides toward the nut assembly 28 thus moving the bridge critical contact point 44 closer to the nut critical contact point.

Slidable movement of the saddles 36 is obtained by the unique structure and operation of the force conversion assembly components shown in FIG. 3. The unique arrangement of levers, and other components facilitate the conversion of rotational, vertical and angular forces to a slidable force which effects slidable movement of saddles 36 along the longitudinal axis of neck 24 (i.e., along the length of strings 114).

In operation, when it is desired to load a string 114 into assembled position where bullet 116 is arranged within a corresponding cavity 30 of the nut assembly 28, and bullet 118 is arranged within a corresponding cavity of a saddle member 36 at bridge assembly 34, the saddle member 36 should be adjusted to slide forward toward the nut assembly 28. This may be accomplished by rotating tuning screw 74 counter clockwise until a corresponding saddle 36 moves to a sufficiently forward position where a string 114 can be loaded without a great deal of tension. As the tuning screw 74 is rotated counter clockwise, the riser 84 is threaded downwardly along the threaded shaft 78. This downward movement of riser 84 forces the lower end 66 of lever arm 62 downwardly so that the lever arms 54 and 62 become arranged in a more extended (i.e., vertically oriented) position.

Similarly, when tuning screw 74 is rotated clockwise, the riser 84 is threaded upwardly along the threaded shaft 78. This upward movement of riser 84 forces the lower end 66 of lever arm 62 upwardly toward the vertically extending portion 50 of the saddle member 36. Thus, lever arms 62 and 54 both become arranged in a more compressed (i.e., horizontally oriented) position. This causes the saddle member 36 to slide away from the nut assembly 28 such that the tension on an associated string 114 is increased until a convergently tuned state is obtained (i.e., when harmonic and pitch tuning are simultaneously achieved). At its uppermost position, the bottom of vertical extension 50 at the end of saddle member 36 fits within recess 67 of lever 62.

The force conversion assembly includes various components including the combination of a portion of saddle member 36, lever arms 54 and 62, tuning screw 74, riser 84 and other components which maintain the foregoing components in assembled position. This assembly allows rotational movement of tuning screw 74 to convert both vertical and angular forces along lever arms 54 and 62 as the riser 84 is moved upwardly and downwardly along the threaded shaft 78. Contact between roller 52 and the underside of base 35 also facilitate conversion of the rotational, vertical and angular forces to a horizontal force which effects longitudinal slidable movement of the saddle member 36.

The structure and operation of the force conversion assembly is such that rotation of tuning screw 74 through a certain rotational distance will effect a relatively large longitudinal movement of a corresponding saddle member 36 when tension in an associated string 114 is relatively small (i.e., when the saddle member 36 is arranged relatively close to the nut assembly 28). Conversely, when the tension in an associated string 114 is relatively high (i.e., when the saddle member 36 is arranged relatively far from the nut assembly 28) rotation of tuning screw 74 through the same rotational distance will effect a relatively small longitudinal movement of saddle member 36. Notwithstanding the disproportional distance of longitudinal movement of saddle member 36 in response to rotation of tuning screws 74 when a corresponding string 114 is under different tensions, the structure and operation of the lever arms 54 and 62 render it relatively easy to rotate an associated tuning screw 74 at all times regardless of the string tension. This is because when the tension in an associated string 114 is relatively high the relatively horizontal orientation of the lever arms 54 and 62 are positioned to provide additional leverage which reduces, or at least substantially maintains, the amount of rotational force required to turn tuning screw 74.

In a preferred embodiment of the present invention, the bridge assembly 34 is shown as a tremolo bridge, which includes a tremolo plate 92. However, it should be appreciated that the present invention covers bridge assemblies that do not pivot and thus are not tremolos. As is known in the stringed instrument art, a tremolo may be used when it is desired to obtain unusual tone variations. This occurs when the tension in all of the strings is rapidly increased or decreased during playing of an electrical guitar. However, it should be understood that various features of the present invention may be used in guitars which do not include a tremolo.

The bridge assembly 34 includes a significant improvement over prior art designs in that it has a tremolo plate 92 with a surface arranged substantially coplanar (i.e., flush) with the surface of the body 22. This provides the advantage of a "hidden" tremolo where it is not apparent that guitar 20 includes a tremolo (as it does not have a traditional tremolo arm), but a tremolo effect may be obtained by depressing the tremolo plate 92 downwardly. The tremolo plate 92 includes a first end 94 connected to the base 35 of bridge assembly 34. A second end 96 of tremolo plate 92 is remote from the base 35. When arranged in assembled position on guitar body 22, the tremolo plate 92 may appear as shown in FIG. 1.

As best shown in FIGS. 3 and 11, the bridge assembly 34 includes an L-shaped bracket 98 which is secured to a lower fixed portion of the bridge base 35. The L-shaped bracket 98 has a vertically extending section and a circular spring connector 100 thereon. A coil spring 102 extending within the body 22 includes a first end connected to connector 100 and a second end secured to a head of mounting screw 104. The mounting screw 104 includes a threaded shaft arranged within a threaded passageway of locking hardware 106 when in assembled position. Locking hardware 106 is arranged within a passageway 107 that extends through the body 22 of guitar 20 at the end thereof. Passageway 107 facilitates access to locking hardware 106 and the mounting screw 104 therein so that a user may selectively adjust the tension in coil spring 102.

With reference to FIGS. 1, 3 and 10, the surface of tremolo plate 92 includes a recess and a passageway (unnumbered) in which adjustable volume control knob 108 is arranged. As also shown in FIG. 1, a receptacle 89 is arranged on the body 22 and is adapted to receive a guitar cord which may be plugged into an associated amplifier (not shown).

FIG. 2 illustrates the tremolo plate 92 when a user exerts a downward force upon the second end 96 thereof and causes it to become depressed into the cavity of the body 22 below the surface of body 22. The functionality of tremolo bridge assembly 34 is similar to prior art tremolos in that as tremolo plate 92 is pushed downwardly, the entire bridge assembly 34 rotates toward the nut assembly 125 and thus tension is decreased in strings 114. When the user releases the force from the forward end 96 of tremolo plate 92, the coil spring 102 biases the bridge assembly 34 and the tremolo plate 92 back to its at rest position as shown in FIG. 1 and tension is returned to guitar strings 114.

If a user desires to momentarily increase the tension in strings 114 while playing the guitar 20, the stopping screw 105 shown in FIG. 11 must initially be adjusted so that it is remote from the bottom of the bridge assembly 34. This will permit the user to increase the tension in associated strings 114 by pressing downwardly on the rear most portion of bridge assembly 34. The second end 96 of tremolo plate 92 will then become raised above the surface 22 of guitar 20. In effect, this creates a higher pitched sound.

The flush arrangement of tremolo plate 92 in its at rest position provides advantages in both use of the tremolo bridge assembly 34 and the overall appearance of the guitar 20. One advantage of the flush tremolo plate 92 is that it provides an open playing surface that does not interfere with movement of a user's hands on the guitar body 22. This arrangement overcomes a problem that existed with prior art guitars here a tremolo arm was raised above the surface of a guitar body. Such prior art tremolo arms did not provide an open playing surface and thus have the drawback of sometimes interfering with a user's hands during playing of the guitar.

Another feature of the present invention relates to a readily removable and replaceable headstock. This aspect of the present invention is shown in FIGS. 1 and 5-7. When a user desires to take advantage of the unique convergence tuning aspect of the present invention, headstock 32 may be utilized. In this embodiment, convergence tuning is accomplished by selective adjustment of tuning knobs 76 of the bridge assembly 34. There is no need to perform any adjustment of the strings 114 at the nut assembly 28. Thus, head stock 32 does not include any rotatable tuning pegs as required for pitch tuning in conventional guitars.

In this embodiment, the nut assembly 28 may be separately connected at an end of the neck 24. However, it should be appreciated that in alternate embodiments, the nut assembly 28 may be formed as part of the neck 24. Regardless of whether the nut assembly 28 is formed as part of the neck 24 or is separately connected to an end of the neck 24 remote from the body 22, it should be appreciated that for the purpose of the terminology used herein, the headstock 32 will be considered to be "connected" to the second end of the neck 24. In the description of the preferred embodiment shown in FIG. 6 which follows, the headstock 32 and alternate headstock 134 are actually directly connected to the housing 125 of nut assembly 28 and are thus, indirectly connected to the end of neck 24. In this arrangement, it is considered as if the headstocks 32 and 134 are still "connected" to the neck 24.

With reference to FIG. 6, a partially exploded rear view is illustrated, where it is apparent that the headstock 32 can be selectively attached to and detached from nut assembly 28. A plate 120 which forms part of the rear portion of cavities 30 of the nut assembly 28 extends outwardly from the connecting end of head stock 32. In assembled position, the plate 120 is arranged adjacent to cavity forming section 122 of the nut assembly 28. In the embodiment shown in FIGS. 6 and 8, the nut assembly 28 includes a housing 125 and the actual nut 131 including the nut critical contact points (unnumbered) which support strings 114.

The head stock 32 has mounting hardware including a central extension rod 124 and a plurality of post holes 130 arranged on the end of headstock 32 on either side of central extension rod 124. These components are useful to facilitate removal and replacement of the headstock 32 with respect to the nut assembly 28 and the neck 24.

As also shown in FIG. 6, nut housing 125 includes an end which abuts the end of the headstock 32 when in assembled position. Nut housing 125 includes a central passageway 126 which is sized and shaped to receive central extension rod 124 of headstock 32. A pair of pins 127 extend from opposing sides of nut housing 125 and are adapted to be inserted within post holes 130 of the headstock 32.

The nut plate 131 is secured to the nut housing 125 by a pair of screws (not shown) which extend within corresponding passageways 127. The entire nut assembly 28 including nut housing 125 and nut plate 131 may be secured to an end of the neck 24 by locking screws 129, the heads of which are visible in FIG. 6.

When the end of the headstock 32 is placed in abutment with the end of nut housing 125, a set screw 132 may be used to secure the headstock 32 in assembled position. In order to remove headstock 32, a user may simply loosen set screw 132. Headstock 32 can then be pulled from its assembled position on nut housing 125.

As shown in FIG. 6, the extension rod 24 includes a flat surface against which an inner end of set screw 132 will abut when head stock 32 is arranged in assembled position. The inner end of set screw 132 may include a teflon coating so that it is free to slide along the flat underside of extension rod 124 when it is not fully tightened thereon. This will allow the user to slide the headstock 32 between a string loading position (shown in FIG. 5), where the headstock 32 is pulled away from the nut housing 125, and a string retaining position where headstock 32 fully abuts against nut housing 125 (shown in FIG. 8). A raised portion (unnumbered) at the end of extension rod 124 acts as a stopping surface with respect to set screw 132 so that headstock 32 cannot be fully removed unless set screw 132 is further loosened or removed.

It may be desirable in certain circumstances to modify the aesthetic appearance of headstock 32. Thus, the present invention allows for readily removing and replacing various headstocks provided that such headstocks include the connecting system features discussed above and shown in FIG. 6. In certa