String tensioner for musical instrument

A string tensioner is configured to apply a substantially constant tension to a string over an operational range even if such string stretches and contracts over time. Tension is provided by a spring. Flexers can attach the spring to a force modulation member and a frame. The flexers preferentially bend out-of-axis so that the spring does not bend out-of-axis when the force modulation member rotates. A dampening system can slow the force modulation member's response to vibrational forces. A flexible stop can prevent rotation of the force modulation member beyond a desired point, but flexes to remain in contact with the force modulation member over a small range of movement.

BACKGROUND

The present disclosure relates to stringed musical instruments, and more specifically to a string tensioner for stringed musical instruments.

Stringed musical instruments create music when strings of the instrument vibrate at wave frequencies corresponding to desired musical notes. Such strings typically are held at a specified tension, and the musical tone emitted by the string is a function of the vibration frequency, length, tension, material and density of the string. These parameters must be maintained to keep the instrument in appropriate tune. Typically, musical strings go out of tune because of variation in string tension. Such tension changes commonly occur when, for example, the string stretches and slackens over time. Tension can also change due to atmospheric conditions such as temperature, humidity, and the like.

Tuning a stringed instrument is a process that can range from inconvenient to laborious. For example, tuning a piano typically is a very involved process that may take an hour or more. Tuning a guitar is not as complex; however, it is inconvenient and can interfere with play and/or performance.

Applicant's previous patents, such as U.S. Pat. No. 8,779,258, teach a constant tension device that uses one or more springs to maintain a near-constant tension on a musical string so that the string will not go out of tune despite changing conditions. The musical string is connected to a force modulation member, which is also connected to a spring. As the length of the musical string changes, the force modulation member rotates, as does the spring. The lever arm upon which spring force is applied to the force modulation member correspondingly changes. The net result is that the tension applied to the string by the spring via the force modulation member remains relatively constant even as the tension within the spring changes. Notably, operation of such structure involves connections and the like that can lead to energy losses.

SUMMARY

The present disclosure discloses aspects that improve constant tension devices, particularly constant tension devices for stringed musical instruments. For example, some embodiments disclose structure that connects springs to parts of the constant tension device in a manner so that, even when the springs are rotated, such springs deflect substantially only in an axial direction, avoiding out-of-axis bending. Some embodiments disclose structure that avoids excessive bending of the musical string upon rotation of the force modulation member. Still further embodiments disclose structure providing a rotation stop that stops further rotation of the force modulation member, but is flexible, and avoids possible separation (and consequential buzzing) during engagement of the stop. Yet other embodiments disclose a saddle structure that is rotatable with substantially little to no friction. Still other embodiments disclose structure for preserving resonance in the sounding portion of the musical string by reducing movement of the force modulation member during such resonance.

In accordance with one embodiment, the present disclosure provides a spring alignment device, comprising a first mount and a second mount; an elongated spring member having a spring axis, a first spring mount and a second spring mount, elongated spring member configured to exert a tension along the spring axis; and the first mount being attached to the first spring mount via an elongated flexer, and the second mount being attached to the second spring mount via an elongated flexer so that the elongated spring member is held in tension between the first and second mounts. The elongated flexers are each configured to bend in a direction out of the spring axis more readily than will the elongated spring member so that the entire length of the elongated spring member is substantially aligned with the spring axis.

In some such embodiments, the elongated spring member is an elongated coil spring.

In accordance with another embodiment, the present specification provides a string tensioner for a stringed musical instrument, comprising a frame; a spring modulation member configured to pivot relative to the frame, the spring modulation member having an arm and a string holder; an elongated coil spring having a first end attached to the arm and a second end attached to the frame so that as the spring modulation member pivots, the coil spring elongates or contracts and a lever arm of the coil spring relative to the spring modulation member simultaneously changes, the elongated coil spring having an axis; a first elongated flexer extending between the arm and the coil spring; and a second elongated flexer extending between the frame and the coil spring. The first and second elongated flexers are selected to bend in a direction out of the spring axis more readily than will the coil spring so that the entire length of the coil spring is substantially aligned with the spring axis.

In some such embodiments, the frame comprises a view slot having a front surface and a back surface, and the spring force modulation member comprises an indicator portion viewable within the view slot. A length of the view slot between the front and back surfaces can be selected so that there is substantially no audible change in the tune of the musical string when the indicator portion moves within the view slot between the front and back surfaces during stretching and contracting of the string.

In accordance with yet another embodiment, the present specification provides a string tensioner for a stringed musical instrument, comprising a frame; a spring modulation member configured to pivot relative to the frame, the spring modulation member having an arm and a string holder configured to connect to a musical string; an elongated coil spring having a first end attached to the arm and a second end attached to the frame so that as the spring modulation member pivots, the coil spring elongates or contracts and a lever arm of the coil spring relative to the spring modulation member simultaneously changes, the elongated coil spring having an axis; a body of the spring modulation member having an arcuate surface; and an elongated flexer extending between the body of the spring modulation member and the string holder, the elongated flexer configured to readily bend so as to conform to the arcuate surface of the body. The string tensioner is configured so that when a tension is applied to the string holder by a musical string, a portion of the elongated flexer bends to conform to the arcuate surface of the body so that the string holder is positioned to hold the musical string in a position extending tangentially from the arcuate surface of the body.

In accordance with yet another embodiment, the present specification provides a string tensioner for a stringed musical instrument, comprising a frame supporting a flexible stop; a spring modulation member configured to pivot relative to the frame, the spring modulation member having an arm, a string holder configured to connect to a musical string and a stop body having a bumper; and an elongated coil spring extending between the arm and the frame. The string tensioner is configured so that when a tension is applied to the string holder by a musical string the spring modulation member is pivoted so that the bumper of the stop body engages the flexible stop and the flexible stop flexes over a range before preventing further pivoting of the spring modulation member.

In accordance with still another embodiment, the present specification provides a musical string saddle assembly for a stringed musical instrument, comprising a support base defining a base cavity; a saddle body configured to fit within and be vertically movable within the base cavity, the saddle body comprising a musical string receiver; a height adjustment member configured to selectively move the saddle body vertically relative to the support base while the support base remains within the base cavity; and a saddle pivot configured to pivotably engage a surface of the stringed musical instrument. The musical string saddle assembly can be configured to be pivotable relative to the surface of the string musical instrument and about the saddle pivot.

In accordance with still another embodiment, the present specification provides a string tensioner for a stringed musical instrument, comprising a frame; a force modulation member configured to pivot relative to the frame, the force modulation member having an arm and a string holder configured to connect to a musical string. A spring is attached to the arm so that force from the spring is communicated to the string via the force modulation member. A dampener is provided to slow response of the force modulation member to forces tending to rotate the force modulation member.

DESCRIPTION

The following description presents embodiments illustrating inventive aspects of the present invention. It is to be understood that various types of musical instruments can be constructed using aspects and principles as described herein, and embodiments are not to be limited to the illustrated and/or specifically-discussed examples, but may selectively employ various aspects and/or principles disclosed in this application. For example, for ease of reference, embodiments are disclosed and depicted herein in the context of a four-string bass guitar. However, principles discussed herein can be applied to other stringed musical instruments such as, for example, violins, harps, and pianos. Similarly, principles discussed herein can be applied to constant tension devices for various uses, including uses other than in connection with stringed musical instruments.

With initial reference toFIG. 1, a guitar30is illustrated. The guitar30comprises a body32, an elongate neck34, and a head36. The neck34extends from the body32to the head36. A plurality of frets44are disposed on the neck34, and a nut46is arranged generally at the point when the neck34joins with the head36. Tuning knobs48are disposed on the head36. Musical strings50are also provided, each having first and second ends52,54. The first end52of each string50is attached to an axle56of a corresponding tuning knob48, and at least part of the string50is wrapped about the tuning knob axle56. Each string50is drawn from the tuning knob48over the nut46, and is suspended between the nut46and a string tensioner60disposed on a front face of the body32. The second end54of each musical string50is attached to the string tensioner60. The suspended portion of the string50, when vibrated, generates a musical note and can be defined as a playing zone61or sounding portion of the strings.

The illustrated embodiment is an electric guitar30, and additionally provides a plurality of pickups64, which include sensors adapted to sense the vibration of the strings50and to generate a signal that can be communicated to an amplifier. Controllers such as for volume control and the like can also be disposed on the body32of the guitar30.

In the embodiment illustrated inFIG. 1, the string tensioner60is depicted schematically. Applicants anticipate that string tensioners having various structures can be employed with such a guitar30.

With reference next toFIGS. 2 and 3, an embodiment of a string tensioner60is presented. The illustrated string tensioner is configured to support four string holder assemblies62, with each assembly configured to hold a single musical string50. To avoid clutter, some components of some of the assemblies have been removed in the illustrated embodiment.

As shown, the string tensioner60comprises a frame64configured to support the assemblies62, and to be mounted in the body of a musical instrument such as a guitar. The frame64includes a frame surface66, which is configured to support four saddle assemblies68.

As shown inFIG. 3, each string holder assembly62comprises a spring force modulation member70configured to rotate, or pivot, about an axle72supported by an axle support74of the frame64. A string holder76is attached to the modulation member70and is configured to hold an end of a musical string (not shown), which extends over and is supported by a selectively-movable saddle. An arm80of the modulation member70connects to a first end88of a coil spring90, which is connected at its opposing second end92to the frame64via a movable shuttle94. As discussed in more detail in Applicant's U.S. Pat. Nos. 8,779,258 and 10,224,009, the entirety of both of which are hereby incorporated by reference, when the musical string elongates or contracts, the spring90correspondingly lengthens or contracts, and also the spring position changes. As such, the line of action of the spring90changes, correspondingly changing a lever arm of the spring90relative to the axle72. This changing lever arm effectively compensates for changes in the force exerted by the spring90as it lengthens or contracts. In this manner, and as discussed in more detail in the documents that are incorporated by reference, the tension applied by the spring90to the string via the force modulation member70remains near-constant over an operation range of string length change even though the spring force exerted by the spring90changes with its changing length.

With additional reference toFIG. 4, a pair of elongated guides96are supported by the frame64, and the shuttle94is configured to slide over the elongated guides96. An adjustment bolt98is also supported by the frame64and is threadingly connected to the shuttle94. As such, when the adjustment bolt98is rotated, the shuttle94is moved linearly along the elongated guides96. An adjustment bolt access hole99is formed through the frame surface66to provide access to each adjustment bolt98. As such, a user can advance a tool into the access hole to rotate the adjustment bolt98in order to place the shuttle94—and thus the angle of the spring90—as desired.

Preferably, tuning of a guitar string is accomplished by adjusting the shuttle position. First, the musical string50is tightened via with the tuning knobs48. The user will then rotate the adjustment bolt98to position the shuttle94(and thus the associated spring90) so that the corresponding string50is in tune. Once the string is in tune, stretching and contracting of the string50over an operating range will be compensated-for by the rotating force modulation member70and spring90so that the musical string remains in tune.

During operation, an angle of the spring90relative to both the shuttle94and the modulation arm80changes as the modulation member70rotates. Due to the structure of some types of spring mounts, this can lead to friction and/or the spring90bending somewhat relative to its axis (particularly at and adjacent the first and second ends88,92of the spring90, which are attached to the arm80and shuttle94, respectively). Thus, the spring90not only lengthens and contracts, but has some out-of-axis bending, which can affect the actual tension applied to the musical string50, possibly compromising predictability and the ability to maintain near-constant string tension.

With particular reference toFIGS. 3-6, an embodiment of a spring mounting arrangement provides flexible members, or flexers100,102, between the spring ends and the shuttle94and modulation arm80. More specifically, a first flexer100is disposed between the first end88of the spring90and the modulation arm80, and a second flexer102is disposed between the second end92of the spring90and the shuttle94. The flexers100,102are configured to be more flexible in an out-of-axis direction than is the spring90, but to exhibit little or no in-axis elongation when subjected to tensions within the operating range. Thus, when the modulation member70rotates, and the angle of the spring90relative to both the shuttle94and arm80changes, the flexers100,102bend out of axis instead of the spring90so that the spring90deflects substantially only in tension along its length, and does not deflect substantially in bending relative to its spring axis. There is little or no friction at points of connection between the spring90and the arm80or shuttle94.

FIGS. 5 and 6show an embodiment of a coil spring90having a spring mount104on each of its first and second ends88,92. Each spring mount104comprises a mount body106to which a plate108is attached. The plate108seats behind a coil of the spring90so that tension applied to the mount body106is communicated via the plate108to the spring90. As shown, a flexer is attached to each spring mount body106.

In the illustrated embodiment, each flexer100,102comprises a thin metal plate or strip configured to readily deflect or bend in an out-of-axis direction, but to not stretch upon application of tension within an operating range of the string tensioner. In a preferred embodiment the flexers are formed of a spring steel having a thickness of about 0.002-0.004 inch. In additional embodiments the flexers100,102may have other structural configurations. Preferably, however, the flexers are configured to be more flexible in out-of-axis bending than is the coil spring90so that the flexers100,102will preferentially bend, and substantially the entire length of the coil spring90will be straight along the spring axis notwithstanding rotation of the spring90. Most preferably each flexer100,102will bend with a substantially constant radius of curvature from the spring mount104to the mount of the corresponding arm80or shuttle94.

In the illustrated embodiment, holes109are formed adjacent the ends of each flexer100,102, and fasteners extending through the holes attach each flexer to corresponding spring mounts104and arm80or shuttle94.

The first flexer100preferably is attached to the modulation arm80. More specifically, the end of the flexer100preferably is sandwiched between a clamp portion110and an end of the arm80, and is secured in place with a pair of fasteners.

A shuttle mount112is configured to attach to the second flexer102so as to connect the second end92of the spring90to the shuttle94. The illustrated shuttle mount112comprises a first clamp114and a second clamp116. The end of the second flexer102is sandwiched between the first and second clamps114,116, which are tightened together with a pair of fasteners.

In the illustrated embodiment, the shuttle94comprises a pair of spaced apart retainers120, and a key receiver122is defined between the retainers120and a shuttle body. The shuttle mount112comprises a keyed portion124that is configured to fit complementarily into the key receiver122of the shuttle94so that offset surfaces126of the shuttle mount engage back surfaces of the shuttle retainers120, with the remainder of the shuttle mount112and the flexer102extending between the retainers120. A fastener preferably attaches the shuttle mount112to the shuttle94.

It is to be understood that various structures and methods can be employed to attach respective ones of the first and second flexers100,102to a modulation member70and to a shuttle94or other structure associated with the frame64.

FIG. 6is a schematic diagram demonstrating, generally, operation of the spring90and flexers100,102when the force modulation member70rotates. As shown, when the modulation member70is in a first position, the flexers100,102both bend relative to the axis of the spring90, while the entirety of the length of the spring between its first and second ends88,92remains substantially in line with the spring axis. As such, substantially the entire force applied to the coil spring90is a tension force applied along the spring axis. As the modulation member70is rotated to a second position (shown in phantom), the flexers100,102continue to bend out-of-axis, but to a differing extent than at the first position. Although the coil spring axis rotates and elongates, it does not substantially bend out-of-axis, and substantially all the spring tension remains applied along the spring axis between the first and second ends88,92.

In some embodiments, during rotation of the force modulation member70the first end88of the spring90moves substantially while the second end92of the spring90does not move or rotate much as compared to the first end88. As such, in some embodiments the first flexer100can be more flexible in out-of-axis bending than is the second flexer102. For example, in one embodiment the second flexer102can be made of a single plate of spring steel having a thickness of about 0.004 inch, while the first flexer100can be made of two plates each having a thickness of about 0.002 inch. Although both the first and second flexers100,102have substantially the same resistance to in-axis elongation, the first flexer100can be expected to be more flexible than the second flexer102in out-of-axis bending. In yet further embodiments, the second end92of the spring90may be attached to the shuttle94via a conventional connection structure, such as a pin, axle or the like, while the first end88of the spring90is connected to the modulation arm80via the first flexer100.

With reference next toFIGS. 7-9B, the illustrated spring force modulation member70preferably comprises a body128defining a bearing housing132supporting a pair of bearings attached to an axle72. As such, the modulation member70rotates freely about the axle72. The arm80extends from the body, as does a stop body130. A bumper134projects from a front surface of the stop body130. The body128has an arcuate top surface136. Preferably the arcuate top surface136has a constant radius of curvature.

A string holder76is spaced from the body128of the modulation member70, but is flexibly attached thereto via a holder flexer140that extends between the body and the string holder76. The illustrated holder flexer140preferably is a thin plate or strip formed of spring steel or the like and preferably has a thickness of about 0.002-0.004 inch. The holder flexer140can be similar to the spring flexers100,102in that the holder flexer140readily bends in an arcuate, out-of-axis manner so as to flexibly attach the string holder76to the body, but resists in-axis elongation. In the illustrated embodiment, a pair of fasteners attach one end of the holder flexer140to the body at the arcuate top surface136, and a pair of fasteners attach the other end of the holder flexer140to the string holder76. As shown, the illustrated holder flexer140generally rests upon, and bends to conform to, the arcuate body top surface136.

With particular reference toFIG. 9A, during use, a base142of a musical string50is attached to the string holder76, and the string50is drawn to and over the associated saddle assembly68, from which it extends into the playing zone61of the guitar. In the illustrated embodiment, tension in the string50will tend to pull on the string holder76, which in turn will pull on the holder flexer140so that the holder flexer140bends over, and conforms to the shape of, the arcuate body top surface136. Preferably the musical string50is generally axially aligned with the end of the holder flexer140that is attached to the string holder76. As such, tension in the string50will deflect the holder flexer140and align the end of the holder flexer140that is attached to the string holder coaxially with the string50so that the string50and holder flexer140extend in a direction tangential to the arcuate body top surface.

FIG. 9Adepicts the force modulation member70at a first position similar to that depicted inFIG. 6. When, due to changes in string length, the force modulation member70rotates to a second position as shown inFIG. 9B, the holder flexer140partially unwinds from the arcuate surface136. However, preferably, the angle at which the holder flexer140departs the arcuate surface136remains substantially the same, and the corresponding angle of the musical string50also remains constant, approaching the associated saddle assembly68at the same angle without regard to the rotational position of the force modulation member70. As such, notwithstanding rotation of the force modulation member70with varying string length, the lever arm A upon which the string50acts upon the force modulation member70remains the same at the first and second positions, and at all positions within the operating range of the force modulation member70. Also, frictional losses that could be expected from out-of-axis bending of the musical string50during such rotation of the force modulation member70are reduced or eliminated by the holder flexer140, which preferentially bends out-of-axis relative to the string50.

With reference again toFIGS. 2 and 3, a frame cover146is attached to or coformed with the frame64. In the illustrated embodiment the frame cover146generally encloses the force modulation member70and includes a space opening toward the saddle assemblies68for the musical string50to access the string holder76. The illustrated frame cover146also includes a plurality of spaced-apart view slots150through which the stop body130of respective modulation member70sextend. As such, a user can detect rotation of the modulation member70by viewing movement of the stop body130within the view slots150. In a preferred embodiment, a user tunes the instrument by adjusting the position of the shuttle94so that the string is in tune while the stop body130is within the view slot150and between the front and back surfaces of the view slot150. Preferably, the length of the view slot150between front and back surfaces152,154corresponds to an operational range of the force modulation member70in which the frequency of the corresponding musical string50will not change sufficient to be aurally detectable. Thus, once correct tuning has been established, as long as the stop body130is maintained between the front and back surfaces152,154of the view slot150(and not in actual contact with either of such surfaces152,154), the tension applied to the string50will be such that the string will be in tune.

With additional reference toFIGS. 10-12, a plurality of flexible stops160are attached to the frame cover146so that one flexible stop160is positioned adjacent to the front surface of each view slot150. Each flexible stop160comprises mount apertures at opposing ends. The frame cover146comprises a plurality of corresponding mount bosses162. The flexible stops160are attached via fasteners that extend through the mount apertures into the mount bosses162. As such, each flexible stop160extends across the path of the stop body130so that the bumper134of the stop body130will engage the flexible stop160generally at its center. In the illustrated embodiment the flexible stop160is generally aligned with the front surface152of the view slot150. It is to be understood, however, that in additional embodiments the flexible stop160can be located somewhat forwardly or backwardly of the front surface152.

In the illustrated embodiment, each flexible stop160comprises three stop plates (164A,164B,164C). The illustrated stop plates164are formed of spring steel having a thickness between about 0.002-0.004 inch. In this configuration, the flexible stop160can deform significantly when the bumper134moves forwardly sufficient to contact the flexible stop160. For example, when a guitarist “bends” a musical string50during play, the string50is pulled, rotating the force modulation member70so that the stop body130of the modulation member70moves forwardly within the view slot150. The bumper134is urged against the flexible stop160with sufficient force so that the flexible stop160deflects, as depicted inFIG. 12. Notwithstanding such deflection, the flexible stop160prevents further rotation of the modulation member70, thus enabling the musical string50to change tune when being “bent” by the user. However, because of the flexing/deforming of the flexible stop160, the bumper134and flexible stop160remain engaged tightly with one another even during minor movements of the stop body130that may occur if the bending force applied to the corresponding musical string50varies slightly and in spite of variations in string tension that may occur due to vibrations in the string50. This provides a good engagement between the bumper134and flexible stop160, lessening the likelihood of buzzing, which may occur if contact between the bumper134and stop is weak or intermittent.

It is to be understood that various materials and structure may be used for the flexible stop160in order to achieve the design goal of the flexible stop160being relatively flexible. For example, a soft, readily deformable metal can be used for the entire stop, or for one or more of the stop plates, and/or a plastic layer may be included. Further, in some embodiments an elastomeric layer may be disposed on the contact plate and/or between one or more of the stop plates164.

In a preferred embodiment, the flexible stop160is configured to flex only a limited range, such as less than 3 mm, and more preferably less than 1 mm, upon application of bending force to the corresponding string50by the musician. In some embodiments the flexible stop160is selected to achieve this limited flexing range upon application of a maximum force to the string that is between about 35-50%, and more preferably about 40%, of the base tension of the musical string. Thus, in some embodiments, the flexible stops for individual strings may be configured differently than one another.

With reference again toFIGS. 1-3, the stop body130of each spring force modulation member70is visible within the view slot150. Preferably, an indicator portion166of the stop body130extends through the view slot150and past the frame cover146. When the illustrated instrument is tuned as discussed above, the stop body130/indicator portion will be disposed within the view slot150but spaced (even slightly) from both the front surface152and back surface154of the view slot150. In one preferred embodiment, the musician preferably tunes the instrument so that the indicator portion166is positioned generally centrally between the front and back surfaces152,154of the view slot150when the string50is at a perfect tune tension. In another embodiment, a musician that wishes to bend notes may tune the instrument so that the indicator portion166is positioned close to the front surface152of the view slot150. As such, when deforming the string so as to “bend” notes, the stop body130will readily be pulled against the front surface152of the view slot150(and/or flexible stop160), preventing rotation of the force modulation member70, and the user's deformation of the musical strings will change the tone of the string50. When the string is released, the stop body130will again be drawn away from the front surface152, and the constant tension features will again be operational.

As the associated musical string50stretches or contracts, the spring force modulation member70will rotate so as to maintain tension in the musical string50within a desired range of perfect tune. The position of the stop body130within the view slot150will change during such rotation. Preferably, the assembly is configured—and the length of the view slot150is selected—so that there is substantially no audible change in the tune of the musical string50when the stop body130moves within the view slot150between the front and back surfaces152,154. Additional embodiments can be configured so that there is substantially no audible change in musical string50tune as long as the stop body130moves less than ⅔, or ½ in other embodiments, of the distance between the front and back surfaces of the view slot150.

If a musical string breaks or is removed, the tension applied by the spring90will be unopposed by any string, resulting in rotation of the modulation member70. However, in the illustrated embodiment, such rotation will be stopped when the stop body130engages the back surface154of the view slot150. As such, the string holder76is kept in an easily-accessible position for loading a replacement string. Also, potential damage to the coil spring90and/or associated flexers that may occur in the event of sudden, unrestricted rotation of the modulation member70, is avoided. Further, the associated spring90is maintained in the position corresponding to correct tuning of the associated musical string50. Thus, upon loading of a replacement string, and tightening of such string using the tuning knobs48, once such string50is tightened sufficient that the stop body130is pulled off the back surface154to a position between the front and back surfaces152,154of the view slot150, the string50will be at or near perfect tune, requiring little, if any, further adjustment of the shuttle94to bring the string into perfect tune.

As discussed above, a base142of a musical string50is connected to the spring force modulation member70and extends to and over an associated saddle assembly68, from which the string extends into a playing zone61.FIGS. 2 and 3depict two embodiments of saddle assemblies68in place on the frame64, although the illustrated frame64is configured for a four-string guitar. It is to be understood that various types and configurations of saddle assemblies can be employed. However, in the illustrated embodiment, the saddle assemblies68are configured so that they can be adjusted to increase or decrease in height in order to provide a desired string action. The illustrated saddle assemblies68can also be moved longitudinally so as to individually adjust the playing length of the corresponding string in order to optimize intonation for the corresponding string50. The illustrated saddle assemblies68further are configured to rotate slightly so as to accommodate lengthening and contraction of the corresponding musical string50without requiring the string to slide substantially over the saddle assembly. Still further, it is contemplated to employ saddle assemblies of different sizes in order to accommodate a user's desired range of string height adjustments as well as string sizes and types. The illustrated embodiment exemplarily displays a large saddle assembly and a small saddle assembly.

With continued reference toFIGS. 2 and 3, and additional reference toFIG. 17, the frame64includes a generally flat frame surface66on which is defined a plurality of raised elongated saddle track members158that are spaced apart from and parallel to one another. Saddle paths160are defined between adjacent saddle track members158, and each saddle assembly68is configured to be movable longitudinally within its corresponding saddle path160. An elongated saddle guide slot162is disposed centrally within each saddle path160so as to help guide movement of the saddle assembly68within the saddle path160in a manner as will be discussed in more detail below. In the illustrated embodiment, each saddle track member158is integrally formed with the frame64and extends upwardly from the frame surface66. The illustrated saddle track members158are generally triangular in cross-section, having a track tip164from which opposing track sides166depend at 45° angles, intersecting the frame surface66at track member bases168. As such, a distance between adjacent track tips164is greater than a distance between adjacent track member bases168.

With particular reference toFIGS. 13-17, the illustrated large saddle assembly68comprises a saddle upper body170configured to be movably supported by a saddle base172. A pivot receiver174of the saddle base172is configured to receive an elongated saddle pivot176. An elongated saddle guide178attaches to the saddle base172so that the saddle pivot176is sandwiched between the saddle base172and the saddle guide178.

The saddle upper body170is configured to be received into a base cavity180that is formed by bottom and side walls183,184of the saddle base172. Elongated vertical guide slots182are formed in side walls184of the saddle base172and are configured to receive complementarily-formed keys186protruding from the saddle upper body170. In this manner, the saddle upper body170can be moved vertically within the base cavity180while the engaged keys186and guide slots182help protect against twisting or other non-vertical movement of the upper body170relative to the base172.

In the illustrated embodiment, the saddle upper body170and saddle base172are configured so that, when assembled as depicted inFIGS. 2, 13 and 14, an angled access path189is defined. The access path189is configured so that when the saddle assembly68is positioned forwardly within the saddle path160, as depicted inFIG. 2, an adjustment tool can be advanced through the access path189and into the adjustment bolt access hole99formed in the frame64to enable a user to adjust the adjustment bolt98

An elongated and arcuate string receiver190is defined along the top surface of the saddle upper body170. The illustrated string receiver190is V-shaped in cross-section, and thus receives a musical string50in a manner so that the string is prevented from moving laterally (i.e., side-to-side), preventing vibration that could cause a buzzing sound. In the illustrated embodiment, a string receiver extension192extends from the saddle upper body170on a side of the saddle assembly facing the string holder76. A receiver slot194formed in the saddle base172is sized to complementarily receive the string receiver extension192when the saddle upper body170is lowered into the base cavity180. Preferably, the string receiver190has an arc selected to optimally redirect the musical string50as it extends from the string holder76onto and over the saddle assembly68and into the playing zone61. It is to be understood that, in some embodiments, the string receiver190is configured so the musical string50, as it is being redirected, may or may not engage the entire length of the elongated string receiver190.

With continued specific reference toFIGS. 13-17, the illustrated saddle pivot176is an elongated bar having a square cross-section. The saddle pivot176is received within the pivot receiver174of the saddle base172, and surfaces within the pivot receiver174are configured to engage the saddle pivot176so as to hold it in a position so that its side surfaces are at a 45° angle relative to the bottom wall183of the saddle base172. A saddle pivot tip198is defined along the lowermost edge between saddle side surfaces. Preferably, the saddle pivot tip198extends a very short distance below the base bottom wall183.

The illustrated saddle guide178is also elongated, having a rectangular cross-section configured to complementarily fit through, yet be slidable within, the saddle guide slot162of the frame64. A pair of spaced apart fastener holes179are formed through the saddle guide178and are configured to align with a corresponding pair of fastener holes that are formed through the saddle base bottom wall183and on opposite sides of the pivot receiver174. As such, when fasteners181are extended through the aligned fastener holes179, the saddle pivot176is sandwiched between the saddle guide178and the saddle base172.

In a preferred embodiment, the saddle pivot176is formed of a material that is harder than the frame surface66, and also harder than the saddle guide178. For example, in a preferred embodiment, the frame64is formed of an aluminum, as is the saddle guide178, saddle base172and saddle upper body170, but the saddle pivot176is formed of a high-strength steel. As such, when the saddle guide178is fastened to the saddle base172with the saddle pivot176sandwiched therebetween, the saddle pivot tip198will slightly penetrate the surface of the saddle guide178, further securing its position between the saddle guide178and saddle base172.

With continued reference toFIGS. 2 and 13-17, and with particular reference toFIGS. 15 and 16, an adjustment hole200is defined in the saddle upper body170and is configured to support a threaded height adjustment screw202therewithin. The height adjustment screw202is positioned and configured to engage an upper edge of the saddle pivot176. By advancing an adjustment tool into the adjustment hole200and into engagement with the height adjustment screw202, a user can threadingly advanced or retract the height adjustment screw202so as to raise or lower the position of the saddle upper body170relative to the saddle base172, thus defining a desired string height. Fastener spaces204may be provided in the saddle upper body170, and are aligned with and configured to receive tips of the fasteners181when the upper body170is at its lowest position. Preferably, the fastener receivers204do not engage the fasteners181, but merely define a space204into which the tips of the fasteners181extend without interfering with the saddle upper body172.

In the illustrated embodiment, the saddle assembly68can be slid along the saddle path160to a desired position corresponding to optimized string intonation. When the corresponding musical string50is tightened so that it is at a desired tune, the force of the string applied to the saddle assembly68will urge the saddle pivot tip198to slightly penetrate the track sides158, thus helping prevent the saddle assembly68from undesired longitudinal movement along the saddle path160.

With particular reference toFIG. 17, preferably the saddle assembly68is placed within the saddle path160so that its saddle guide178extends through the saddle guide slot162and the saddle pivot tip198rests upon track sides166of opposing saddle track members158. As such, the saddle pivot tip198(and saddle base bottom wall) is spaced from the frame surface66and supported by opposing saddle track members158. Thus, the saddle assembly68can pivot about the saddle pivot tip198over a selected angular range without the saddle base bottom wall183engaging the frame64.

In the illustrated embodiment, the fastener181heads are wider than the saddle guide slot162. Thus, if the frame64is upended, the blocking surface206engages edges of the fastener heads, which will not fit through the saddle guide slot162, and thus the saddle base172will not unintentionally fall out of the saddle guide slot162.

With the saddle assembly68in place and supporting a tuned musical string50, the saddle assembly68is configured to accommodate and enable the beneficial operation of the spring force modulation member70. More specifically, as a musical string stretches or contracts, the spring force modulation member70is configured to rotate so that a constant or near-constant tension is maintained in the corresponding musical string50. Also, since the saddle assembly68is secured in place to prevent longitudinal movement, the longitudinal movement of the musical string50during expansion or contraction will not change the longitudinal position of the saddle assembly68, thus maintaining the correct intonation position. Further, and with additional reference toFIG. 3, to prevent or alleviate the musical string50from sliding over the surface of the string receiver190(which would create friction forces resisting string movement), the saddle assembly68can pivot about the saddle pivot tip198. As such, this configuration accommodates substantially unrestrained lengthening and contraction of musical strings (over a defined operational range) while maintaining such strings at their desired tuning tensions.

In the illustrated embodiment, the upper body170is not restrained within the base.172Rather the downwardly-directed force of the musical string50keeps the upper body170engaged within the base cavity180. In additional embodiments, structure can be provided to prevent or inhibit the saddle body170from being fully removed from the base cavity180. Such structure can include, for example, a horizontally-directed screw supported in one of the sidewalls184of the base172and arranged either to prevent vertical movement of the upper body170altogether or to define a top limit for vertical movement of the upper body relative to the base. Other structure can comprise a high-friction member, such as a textile layer or a spring-biased member, arranged between one or more of the base side walls184and the saddle upper body170.

With reference next toFIG. 18, an embodiment of a small saddle assembly68preferably incorporates principles and structure having similarities with the large saddle assembly discussed in detail above. However is to be understood that the particulars of such embodiments may be different, including accommodations for the smaller size. For example, in the illustrated small saddle assembly68, the saddle upper body string receiver190does not include a string receiver extension. Rather, the saddle base includes a pair of base string receiver portions208configured to align with the string receiver190when the upper body170is at its lowest position relative to the base172.

With reference again toFIG. 2and additional reference toFIG. 19, in the illustrated embodiment, an intonation marker can be employed to mark the proper longitudinal placement of a saddle assembly so that if the string50is removed, and the saddle assembly68becomes free to move on its own, a user can know the proper location for the saddle assembly when the instrument is restrung. It is to be understood that various structures and methods can be employed for marking the proper intonation position. For example, in one embodiment, a user may simply place a sticker on the frame surface66at the proper intonation position.

In the illustrated embodiment, an intonation marker assembly210comprises an elongated threaded rod212upon which a marker214is placed in a manner so that when the rod212is rotated, the marker214is advanced or retracted along the length of the rod212. Preferably, an intonation marker slot216is formed through the frame64within each saddle path160, and the intonation marker assembly210is placed within the marker slot216. The illustrated intonation marker assembly210includes a knob217configured to rotate the threaded rod212. A first spring218extends between the knob217and the marker214, and a second spring219extends from the knob217to the frame64. In use, a user turns the knob217until the marker214just touches the back side of the associated saddle assembly68, preferably when the saddle assembly is rotated counter-clockwise (i.e., when the stop body130is resting against the back surface154of the view slot150—at the extreme range of rotation of the saddle assembly68). The marker214is left in that position.

In the illustrated embodiment, the saddle assembly68can move longitudinally without restraint while the string50is removed or loose. Thus, placement of the saddle assembly68for proper intonation can be lost when the string is removed. In this embodiment, when restringing the instrument the user will move the saddle assembly68so that it just touches the marker214when the saddle assembly is rotated counter-clockwise to the end of its range (while the stop body130is resting against the back surface of the view slot150). The musical string50is then placed upon the saddle assembly68and tightened and appropriately tuned. During tuning, it is anticipated that the saddle assembly68will rotate clockwise and away from the marker214(as the stop body130is moved away from the back surface154of the view slot150) so that the saddle assembly68will not contact the marker214during play. Notably, during play of the instrument, it can be anticipated that there will be vibrations within the frame64. The first and second springs218,219help prevent the intonation assembly from buzzing due to such vibrations, and will also help prevent buzzing should the saddle assembly68contact the marker214during instrument play.

It is to be understood that various iterations and structural alternatives can be employed for the intonation marker assembly. For example, instead of or in addition to the rod being threaded, the marker can have a screw that is tightened onto the rod when the marker is appropriately placed in order to mark the position and retain the marker at the selected position. Additionally, in another embodiment the spring can be connected to the marker and threaded through the knob so as to be configured to be lengthened or contracted upon rotation of the knob.

With reference next toFIGS. 20 and 21, another embodiment of a string tensioner60is presented. The illustrated string tensioner60is also configured to support four string holder assemblies62, with each assembly configured to hold a single musical string50, and to avoid clutter, only one of the string holder assemblies62is shown. The illustrated string tensioner60comprises a frame64configured to support the assemblies, and to be mounted in the body32of a musical instrument such as a guitar30. The frame64includes a frame surface66, which is configured to support four saddle assemblies68.

With additional reference toFIGS. 22-25, the saddle assembly68comprises a base172having a horizontally-oriented longitudinal adjustment hole222configured to threadingly engage a longitudinal adjustment bolt220. An intonation boss224extends upwardly from the frame surface66corresponding to each saddle assembly68. The intonation boss224includes an aperture226through which the longitudinal adjustment bolt220extends. The aperture226is configured so that the head of the longitudinal adjustment bolt220will not fit therethrough. As such, rotation of the longitudinal adjustment bolt220adjusts the longitudinal position of the saddle assembly base172upon the frame surface66.

A pair of height adjustment holes200are formed on opposing corners of the saddle assembly base172. Each height adjustment hole200is configured to threadingly receive a height adjustment bolt202. To adjust the height of the saddle assembly68, and thus the string height, a user rotates the height adjustment bolts202, which engage the frame surface66, but are not threadingly engaged with the frame surface66. In the illustrated embodiment, the aperture226of the intonation boss224is substantially oval so that the intonation bolt220can move vertically with the saddle assembly base172without changing its angular orientation. When no string is supported by the saddle assembly68, the saddle assembly is prevented from falling off the frame64by the longitudinal adjustment bolt220and intonation boss224.

With continued reference toFIG. 22, the saddle assembly base172includes an inclined portion configured to provide an access path189for a tool to access the shuttle adjustment bolt access hole99formed through the frame surface66when the saddle assembly68is in a forward position.

With reference again toFIGS. 22-25, the saddle assembly base172pivotably supports a saddle body170having a string receiver190configured to accept and retain a musical string drawn over and within it. The string receiver190is formed on an uppermost portion of the saddle body170. Front and rear body surfaces222,224extend from opposing ends of the string receiver190, and taper to meet at a pivot tip230. In the illustrated embodiment the pivot tip230comprises an elongated and straight pivot edge232extending in a direction generally normal to an axis of the string receiver190. The front and back body surfaces222,224preferably meet each other at a tip angle of less than 90°, and more preferably between about 50-85°, and even more preferably between about 75-80°. In the illustrated embodiment, a first extension234and a second extension236extend outwardly at and adjacent the pivot tip230so that the saddle body170is much wider along its pivot tip230than it is across the string receiver190.

A body receiver240is formed within the saddle assembly base170and is configured to receive the saddle body170so that the saddle body170can pivot within the body receiver240. The body receiver240comprises a front surface242and back surface244arranged in substantially a V-shape, with the V having an angle greater than the tip angle of the saddle body170. Most preferably, the V angle is 10-40° greater than the tip angle. As such, the saddle body tip230is received and supported by the V, and can pivot over a range substantially without friction about the V.

In the illustrated embodiment, the string receiver190has a constant radius of curvature along its length, and the radius of curvature is taken about the pivot tip230. As such, and as depicted inFIGS. 26A and 26B, when the musical string50is drawn over the saddle body170and retained in the string receiver190, the bending of the string50is the same no matter its position along the string receiver190. As an example of operation, if a musical string50and the saddle body170is in a first position as depicted inFIG. 26A(and similar to the discussion in connection withFIGS. 9A and 9B), contraction of the string50may cause the saddle body170to pivot to a second position as depicted inFIG. 26B. During such movement, the saddle body170pivots substantially without friction losses, and instead of the string50sliding over surface of the string receiver190, the pivoting saddle body170simply supports the string50at a different portion along its length. Also, even though the saddle body170has pivoted, the string50releases from contact with the string receiver surface of the saddle body at substantially the same point relative to the saddle body base172, which doesn't move. Thus, the playing length of the string50, and thus intonation, remains the same during elongation or contraction of the string50.

With reference again toFIGS. 22-25, a retainer passage248is formed longitudinally through the saddle body170. An elongated retainer post250is supported by the saddle body base172and extends longitudinally across the body receiver240and through the saddle body retainer passage248. Preferably, the retainer passage248is sized and shaped to be larger than the retainer post250so that the retainer post250does not interfere with pivoting of the saddle body170.

When the string50is drawn over the saddle body170and tightened into place, a portion of the string force bending over the string receiver urges the saddle body assembly68against the frame surface66. Most preferably the retainer passage248is configured to provide sufficient clearance space so that the retainer post250never contacts the saddle body170during use when a string50is drawn over the saddle body170. If, however, a string breaks or is removed, the retainer post250will prevent the saddle body170from falling out of the body receiver240.

As discussed above, during stretching and contracting of the string50, the force modulation member70is configured to rotate with very little friction so as to make adjustments so that the tension applied to the string50remains sufficiently constant over an operational range so that the string aurally stays in tune. As is well known, musical notes are generated by vibrations in the playing zone61, or sounding portion, of the string50. In the illustrated embodiments, the portions of the string50on the opposing side of the nut46and string receiver190are substantially isolated from the vibrations in the sounding portion. Once plucked, a musical string50will continue emitting sound, or will sustain, until vibration stops due to interference with the string by the user or other factors, such as friction, that draw energy from the vibrating string50. Applicant has determined that a vibrating musical string can actuate back-and-forth rotation (referred to herein as rotational vibration) of the force modulation member70on a small scale corresponding to the vibration frequency of the string. While such rotational vibration of the force modulation member70does not substantially affect tune of the string, it can act to drain energy from the string, potentially lessening the length of time string vibration is sustained.

With reference next toFIGS. 27-29, in accordance with further embodiments, string holder assemblies62may be configured to dampen rotational vibration of the force modulation member70, preferably without substantially increasing friction that would resist operation of the force modulation member.

With specific reference toFIG. 27, in one embodiment, a mechanical dampener260is installed in a string holder assembly62. In the illustrated embodiment, the mechanical dampener260is installed within the coil spring90. The illustrated mechanical dampener260comprises a chamber262filled with a fluid and attached to the second coupling104. A rod264extending from the first coupling104extends into the chamber262and includes a plunger266. A seal268prevents fluid from exiting the chamber262. In operation, when the force modulation member70is prompted to rotate (such as during stretching or contraction of the musical string), the plunger266slows, or dampens, the reaction time of the string holder assembly62. However, the plunger266does not prevent or limit full operation of the assembly. During normal operation, in which musical strings elongate or contract relatively slowly, it is expected that the dampener260will have substantially no effect on operation.

When a vibrating string50would tend to induce rotational vibration to the force modulation member70in a first rotational direction, the dampener260will slow reaction to the force. Since the vibration is back and forth at high frequencies, the vibrating string50would almost immediately switch to induce rotation of the force modulation member70in a second, opposite rotational direction. Again, the dampener260will slow reaction to the force. Due to such slowed, reaction, rotation of the force modulation member70will be reduced if not eliminated by the mechanical dampener260. As such, little or no energy from the vibrating string will be drawn away by rotational vibration of the force modulation member70, and sustain of string vibration is preserved.

In the illustrated embodiment, the mechanical dampener260is disposed within the coil spring90. It is to be understood that such a mechanical dampener can have any of many structural configurations and can be placed in other areas of the string holder assembly62so as to dampen rotational vibration of the force modulation member70.

With reference next toFIG. 28, in another embodiment, a weighted member270is attached to the force modulation member70. In the illustrated embodiment, the weighted member270comprises weighted wheels disposed on opposite sides of the arcuate surface136and configured to rotated with the force modulation member70. Most preferably, an increased weight is disposed along the outer rim272of the weighted wheel270. As such, due to principles of rotational inertia, the energy requirement to induce rotation of the force modulation member70having the weighted wheels270is much greater than that for a force modulation member70configured as inFIGS. 7 and 8. In this embodiment, the weighted member270is considered an inertial dampener. For example, when a vibrating string would tend to rotate the force modulation member70in a first rotational direction, the inertial dampener270will slow reaction, as more energy is required to induce such rotation. The vibrating string almost immediately switches to apply an opposite force tending induce rotation of the force modulation member70in a second, opposite rotational direction. Again, the inertial dampener270will slow reaction to the applied force. Due to such slowed reactions, rotation of the force modulation member70to vibration will be reduced if not eliminated by the inertial dampener270. As such, little or no energy from the vibrating string50will be drawn away by rotational vibration of the force modulation member70, and sustain of string vibration is preserved. However, during string changes that involve a consistent force change applied over a comparatively long period of time, rotational speed is a less-significant factor, and the inertial dampener270will allow full and unrestricted adjustment operation of the string holder assembly62.

In the embodiment discussed in connection withFIG. 28, the weighted member270is a weighted wheel with weight distributed substantially evenly about the axle72of the force modulation member70. With reference next toFIG. 29, in another embodiment, a weighted member276may not be evenly distributed about the axle72. In this embodiment, the weighted member comprises a slug278attached to the modulation arm80of the force modulation member70. In the illustrated embodiment, attachment of the slug278greatly increases the rotational inertia of the force modulation member, and comprises an inertial dampener276operating along similar principles as discussed above. It is to be understood that inertial dampeners having many different sizes, shapes, and configurations can be employed in additional embodiments to increase the rotational inertia of the force modulation member70and/or other structures of the string holder assembly62.

Inventive principles have been presented herein in the context of a stringed musical instrument, and specifically a 4-string guitar30. However, it is to be understood that the principles discussed herein can be employed with other stringed musical instruments, such as 6- or 12-string guitars, other handheld string instruments such as cellos, violins and the like, and heavy stringed instruments such as pianos. The principles discussed herein can also be employed in other contexts, such as in constant tension devices and/or devices in which spring alignment is desired.

The embodiments discussed above have disclosed structures with substantial specificity. This has provided a good context for disclosing and discussing inventive subject matter. However, it is to be understood that other embodiments may employ different specific structural shapes and interactions.

Although inventive subject matter has been disclosed in the context of certain preferred or illustrated embodiments and examples, it will be understood by those skilled in the art that the inventive subject matter extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the disclosed embodiments have been shown and described in detail, other modifications, which are within the scope of the inventive subject matter, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the disclosed embodiments may be made and still fall within the scope of the inventive subject matter. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventive subject matter. Thus, it is intended that the scope of the inventive subject matter herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.