Tremolo mechanism for a stringed musical instrument with pivoting string anchor

A tremolo mechanism having a novel roller mounted beneath a tensioned string of a stringed musical instrument is described. During oscillatory movement, the tensioned string exerts both a static and a vibratory force on the roller. The roller rotates in relation to the tensioned string such that the static force is generally greater than any component of the vibratory force. The novel roller may be a saddle roller with a saddle block having two opposing block walls which form a roller cavity. The block walls each have a roller bore aligned along a roller axis. The saddle roller includes a cylindrical body attached to a roller pin and a circumferential seat receiving a tension string. The roller pin is rotatably disposed such that the saddle roller is in the saddle block cavity. The roller axis extends obliquely to define an oblique roller angle.

BACKGROUND OF THE INVENTION

The present invention relates generally to mechanisms for tuning or detuning a stringed musical instrument. Specifically, the invention relates to a mechanism for changing the pitch to create vibrato effects and other pitch variations in a stringed musical instrument. The invention also relates to a mechanism for reducing transmission of vibration noise between bridge and other components of tuning devices for stringed musical instruments.

A tremolo mechanism functions by changing the tension of all of the strings of an instrument simultaneously to create a pitch change during playing of the instrument to create a vibrato sound. As used with electric guitars, a tremolo mechanism typically incorporates a tailpiece pivotally joined to a base support mounted on the body of the guitar. A tuning assembly attached to the frame of the tailpiece is utilized to anchor the end of each of a plurality of tensioned strings strung over the guitar's bridge. In such a mechanism, a counter spring is utilized to counteract the reactive bias of the plurality of tensioned strings upon the tailpiece. A tremolo arm is connected to the tailpiece for pivoting of the tailpiece about the base while simultaneously playing the instrument.

A significant problem with such tremolo mechanisms regards to the pitch relationship between the individual strings. In earlier devices, all strings of the instrument are moved the same distance when the mechanism is actuated. Since the higher pitched strings of the instrument generally have much greater elasticity than the lower strings, the lower pitched strings exhibit a greater change in pitch for a given change in string length. For example, if a chord is played on the instrument, and the tremolo mechanism is actuated, the length of each string changes an equal amount. The low pitched strings of the instrument detune (i.e. change pitch) more than the high pitched strings, and the pitch relationships within the chord are lost.

The insufficiency of conventional tremolo mechanisms in maintaining pitch relationships as the tailpiece is pivoted during instrument play has been recognized by inventors in the prior art. An example of a tremolo mechanism adapted to maintain pitch relationships is shown in one of the present inventor's prior patents, U.S. Pat. No. 4,632,005 (the '005 patent) issued to Steinberger on Dec. 30, 1985, entitled “Tremolo Mechanism for an Electric Guitar.” The '005 patent teaches use of a roller bridge disposed atop a base mounted on the body of a guitar. The roller bridge includes a plurality of saddle rollers assembled on a support surface of the base. A plurality of anchor devices are slidably mounted on a plate providing a second support surface mounted on the tailpiece frame. The anchor devices are each aligned parallel with the axis of the tensioned string strung across a corresponding saddle roller and anchor the end of the tensioned string. The anchor device includes a slotted cylindrical bore adapted to hold a disc shaped ball affixed to the end of the tensioned string. Each anchor device is connected to a spring-biased threaded rod, which may be operated to position the anchor device longitudinally so as to adjust the pitch of such string.

The '005 Patent teaches joining the tailpiece to the base by means of a detuning pivot having a pivot axis which is oblique with respect to the string plane defined generally by the plurality of strings. Thus, for a selected radial displacement of the tailpiece about the pivot axis, the string ends of the individual strings are moved varying distances with respect to the corresponding bridge roller so as to generally preserve the pitch relationships between the strings as the tremolo device is employed.

Although a significant step in the art of preserving pitch relationships as the tremolo mechanism is used during guitar play, the device of the '005 Patent has room for improvement. One issue encountered in using the mechanism is the tendency of the string end anchors to malfunction. Movement of the tailpiece causes changes in both the magnitude and direction of tension force exerted on the string end ball disposed in the slotted cylindrical bore of the anchor mechanism. Friction may cause the disc shaped balls to jam or cock in the anchor bore. Such jammed balls change the designed geometry of the bridge break angle and change the designed distance between the anchor point and the portion of string held in the bridge roller (herein termed “string apex”). Jammed balls may also become displaced from the bore or may suddenly slip from a jammed position to an aligned position during play. All of these malfunctions affect the amount of change in string length between the anchor mechanism and the bridge, and thus affect the pitch of the string.

Accordingly, what is needed is an apparatus that provides for the alignment of the anchor, string end and the string apex. Such alignment apparatus should react continuously, rapidly and without detectable frictional effects as the tremolo mechanism is displaced through its designed range of rotational freedom relative to the detuning axis.

An additional problem common to roller bridge mechanisms such as the tremolo mechanism of the '005 patent is vibration noise transferred from an oscillating string to the roller mechanism and therefrom to adjacent roller mechanisms and strings. When a guitar string is plucked and released, the string vibrates in multiple directions in the transverse plane. A string vibrating within the roller seat causes the roller to vibrate as well. Since the roller is connected to the saddle block via a roller pin press-fitted through the roller, components of string vibration that are parallel to the roller pin cause the roller and roller pin to vibrate axially within the bores of the saddle block wall. Vibrations within the saddle block wall are transmitted to adjacent saddle block walls and to other bridge components. This vibrational “cross-over” noise is detrimental to the acoustic characteristics of the instrument. Thus, it is highly desirous that a means of eliminating such “cross-over” noise be incorporated into tremolo mechanisms as well as in general roller bridge mechanisms.

Accordingly, what is needed is an apparatus that prevents axial vibration of such roller and roller pins within the bores of saddle blocks of saddle rollers. Such apparatus should minimize the frictional effects of noise suppression and not interfere with the roller function in supporting the tensioned string.

A third disadvantage of the tremolo apparatus of the '005 patent is its limited combination of locking positions and the inability of it and other prior art tremolo mechanisms to provide a plurality of locked positions separated tonally by only the smallest chromatic intervals. The '005 patent teaches that the lock is positioned about the longitudinal midpoint and on one side of the tailpiece frame. The lock is operated by means of the handle for positioning a locking bar in one of three (3) locking seats that are disposed on an extending rod and in opposition to the locking ridge. The lock has only one locking position wherein the lock prevents displacement of the tailpiece frame from the seat in either direction of rotation about the detuning axis (herein termed a “positive control” locking position). This is accomplished in the '005 patent apparatus by placing walls or stops on either side of the central seat of the locking mechanism so as to create a channel to receive and hold the locking bar. The lock has two additional locking positions, one on either side of the central locking channel. The additional locking positions have only one stop that is disposed between the locking position seat and the central seat. Displacement in the opposite direction of rotation is prevented by the counter bias of the counter spring holding the locking ridge against the stop.

The method of tuning the stringed instrument of the '005 patent requires that the tremolo mechanism be first locked in the central locking seat. The individual strings are then tuned and the tremolo mechanism is unlocked. Tune is restored by adjustment of the counter spring. The result is that the tailpiece frame in its equilibrium position is necessarily generally aligned with the radial position of the tailpiece frame corresponding to that when the lock is locked in the central channel. The tremolo device of the '005 patent can adjust pitch up or down only one full chromatic step by engaging the lock in the corresponding additional locking positions.

Additionally, the lock of the '005 patent is very sensitive to any deviation from an intermeshing alignment of the component parts of the lock as the lock is placed in a locking position. Because the locking components are rigidly connected, an exact intermeshing of the component parts is necessary for the lock to function properly. While continuing to play the instrument, the user must properly first operate the handle as a lever to deflect the tailpiece to very closely align the locking components and then rotate the handle to engage the locking components. Not surprisingly, misalignments are common and may prevent the lock from locking or may damage a lock component.

Accordingly, what is needed is a tremolo lock mechanism that provides for tuning of the instrument such that the tailpiece frame may be aligned in any of a plurality of equilibrium positions, each corresponding to one of a plurality of positive control locking channels. Such a tremolo device should be capable of adjusting the pitch of the strings by any of a plurality of half chromatic steps by engaging the lock in corresponding locking positions.

Additionally, what is needed is a tremolo lock mechanism that accommodates misalignment of intermeshing component parts during the process of locking while neither failing to lock nor damaging a lock component.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description or will be learned by practice of the invention.

BRIEF SUMMARY OF THE INVENTION

The tremolo mechanism of the present invention includes a novel and advantageous pivoting anchor assembly. For each tensioned string extending from the bridge, a pivoting anchor assembly provides for the continuous, rapid and near frictionless alignment of a knife edge pivot, a string end anchor holding a string end, and the string apex in response to changes in the direction and magnitude of the tension force exerted along the tensioned string, such changes created as the knife edge pivot is displaced relative to the string apex during operation of the tremolo mechanism.

In one embodiment of the present invention, the tremolo mechanism further includes tailpiece assembly including a frame joined to the base by means of a detuning pivot defining a detuning axis. The detuning axis is oblique with respect to the string plane defined by the plurality of tensioned strings. The frame further includes a plurality of tuning assemblies each including a pivoting anchor assembly receiving the end of a tension string extending from the saddle roller. An adjustable counter-spring assembly is provided to balance the reactive force of the tensioned strings.

Each novel pivoting anchor assembly of the present invention includes a pivot support structure, a pivot and an anchor structure for receiving and holding an end of a tensioned string. In one preferred embodiment, the pivoting anchor assembly includes a rate screw receiving an anchor block. The anchor block includes a string end anchor, a jaw opening and a knife edge extending into the jaw opening. An upper portion of the rate screw includes a circumferential knife edge seat and extends through the jaw opening such that the knife edge is received within the knife edge seat, so as to form a knife edge pivot. The knife edge pivot allows the anchor block with the string end anchor to pivot both axially and radially relative to the rate screw in response to changes in the magnitude and direction of the tension force exerted long the tensioned string. The changes in the tension force bias the position of the anchor block and string end anchor so as to align the knife edge pivot, the string end anchor holding a string end, and the string apex.

In one preferred embodiment of the present invention, the novel rate screw of pivoting anchor assembly is adjustably disposed upon a tuner arm which is pivotally attached to the frame. Operation of the rate screw results in a displacement of the knife edge seat and, thus, the pivoting anchor assembly relative to the string apex. Similarly, operation of the tuning assembly pivots the tuning arm about the frame resulting in displacement of the pivoting anchor assembly relative to the string apex. A third mechanism for displacing the pivoting anchor assembly relative to the string apex is rotation of the frame relative to the detuning axis. Each of these displacements of the pivoting anchor assembly relative to the string apex tends to change the magnitude and direction of tension forces exerted through the tensioned string which, in turn, reactively biases the string anchor so as to maintain the alignment of the knife edge pivot, the string anchor and the string apex.

An additional novel feature of the tremolo mechanism of this invention includes the block retainer assembly which limits the displacement of the knife edge from the knife edge seat. In one preferred embodiment the block retainer assembly includes a trailing portion of the anchor block which extends towards a retaining surface disposed on the tuner arm and is separated there from by a clearance distance. The seat depth of the knife edge pivot is generally greater than the clearance distance such that displacement of the knife edge from the knife edge seat is limited by contact of the trailing portion with the retaining surface while maintaining the knife edge within a portion of the knife edge seat. In a second preferred embodiment the block retainer assembly includes a retaining spring extending from the tuner arm and engaging the anchor block so as to bias the knife edge against the knife edge seat.

DETAILED DESCRIPTION OF THE INVENTION

A novel tremolo mechanism10of the present invention is shown inFIGS. 15aand15battached to a guitar1having a body3, a neck5, and a plurality of tensioned strings12, each string12anchored at one end to the neck5and extending over the body3in a generally parallel manner. A preferred embodiment of the tremolo mechanism10of the present invention is shown inFIGS. 1-4. When used with a guitar1, the tremolo mechanism10includes a base20mounted to the body3of the instrument. The base20includes a support surface25(seeFIG. 8) and two support walls21disposed on either side of the base20. Vibratory endpoints for the plurality of tensioned strings12are provided by a bridge30. The bridge30includes a plurality of saddle assemblies31disposed on the support surface25. A saddle clamp28aligns the saddle roller assemblies31between the support walls21. Each saddle roller assembly31includes a saddle roller34having a circumferential seat35disposed to receive one of the plurality of tensioned strings.

Alternatively, the base20may be a support of any type which will anchor a detuning mechanism to the instrument and allow for pivotal movement thereon. For example, a pair of posts could be attached to the instrument, or the detuning mechanism could be pivotally attached to a bracket or other anchoring device, or directly to the instrument.

The tremolo mechanism10further includes tailpiece assembly18including a frame60carrying a plurality of tuning assemblies90. The frame60is joined to the base20by means of a detuning pivot50(seeFIG. 13), so as to pivot the frame60about the base20during detuning operation of the tremolo mechanism10. In the two preferred embodiments shown inFIGS. 1-4andFIG. 8, the detuning pivot50includes a pair of knife edge pivots aligned to define a detuning axis51about which the frame60rotates relative to the base. The detuning axis51is oblique with respect to the string plane14and defines a detuning angle53therewith.

The frame60further includes a plurality of tuning assemblies90(seeFIG. 5a) for anchoring and individually tuning the plurality of tensioned strings12of the instrument1. Each tuning assembly90supports a pivoting anchor assembly70which is oriented in general alignment with a saddle assembly31. The pivoting anchor assembly70receives and holds the end of a tension string12extending from the saddle roller34of such saddle assembly31. The tremolo mechanism10also includes a counter-spring assembly69providing a spring force upon the frame tongue62to balance the reactive tension force of the tensioned strings12retained in the pivoting anchor assemblies70.

Additionally, the tremolo mechanism10includes a lock110that can be positioned in an unlocked configuration or in any of a plurality of locking configurations, each locking configuration corresponding to a selected radial angle with respect to the detuning axis53. A tremolo arm100is disposed on the frame60to facilitate manual pivoting of the tailpiece frame60about the detuning pivot axis51when the lock110is in an unlocked configuration and to facilitate operation of the lock110.

Saddle Roller with Oblique Roller Angle

Referring now toFIG. 3, each saddle assembly31shown includes a saddle block32having two opposing block walls33which form a roller cavity there between. Referring now toFIGS. 8 and 9, the block walls33each have a roller bore37, the roller bores37disposed in alignment along a roller axis39. The saddle roller34of this preferred embodiment includes a cylindrical body attached to an axle, preferably a roller pin36. The saddle roller34further includes a circumferential seat35receiving a tension string12. The roller pin36extends across the saddle block cavity and is rotatably disposed in the roller bores37such that the saddle roller34is disposed in the saddle block cavity. In this configuration, the saddle roller34is fixed upon the roller pin and the combination rotates about the roller axis39.

In the preferred embodiment shown inFIG. 9, the roller bore37disposed closest to the support surface25extends only partway through the corresponding block wall33so as to form a bearing seat while the second roller bore37extends completely through the second block wall33so as to form an exterior bore opening in the exterior of the second block wall33. This configuration is useful in assembly of the saddle assembly31. A saddle roller34may be disposed in the roller cavity and a roller pin38may be inserted by means of the exterior bore opening, through the second roller bore37, through an axial bore disposed in the cylindrical body of the saddle roller34and into the first roller bore37. In the preferred embodiments, the saddle roller43is press fitted upon the roller pin38. The roller pin38and roller bores37are sized and shaped so as to reduce the frictional contact between the roller pin38and roller bores37. The materials comprising the saddle walls33and the roller pin38are selected to provide rigidity and strength and to reduce friction between the rotating roller pin38and the surface of the roller bores37.

The present invention includes roller supports other than saddle blocks and also includes any device for supporting a bridge roller rotating about a roller axis generally known in the arts. Alternate embodiments of the present invention also include such roller axles and roller combinations as are generally known in the arts. For example, the present invention includes roller axles rotating on journal and thrust bearings disposed within roller bores and further includes rollers rotating about axles fixed in the roller bores.

Referring now toFIG. 9, a saddle assembly31is shown disposed upon the support surface25and includes a saddle roller34disposed on a roller pin36. The roller pin36extends along a roller axis39that is oriented so as to extend obliquely with respect to the sliding plane defined by the support surface25. To illustrate this geometric relationship, a reference line146is shown extending parallel to the support surface25and intersecting the roller axis39so as to define an oblique roller angle38.

When the tremolo mechanism is installed on an instrument, similar geometric relationships are created between the roller axes39of the saddle assemblies31and the tensioned strings12of the instrument. Referring again toFIG. 9, a tensioned string12is shown received in the circumferential seat35so as to form a string apex87. The tensioned string12exerts a static force on the roller34and further exerts a vibratory force on the roller34during oscillatory movement of the string12. In the transverse, cross-sectional view shown, the tensioned string12defines a string axis along the portion of its length extending across the body of the instrument (not shown). The static force is exerted along a static force axis140which extends perpendicular to the string axis140. The tensioned string12, in combination with the static force axis140, further defines a string plane14as lying along the string axis and being generally perpendicular to the static force axis140. In alternate embodiments of the present invention, the string plane is defined by the plurality of strings12extending in a parallel manner over the surface of the body3. The roller axis39is oriented so as to be oblique with respect to the string plane14. As shown inFIG. 9, the string plane14intersects the roller axis39so as to define an oblique roller angle38.

The static force exerted on the roller34is necessarily transmitted through the roller pin36to the support walls33. According to the principles of vector mechanics, the static force exerted through the roller pin36is resolved into a roller axis component142exerted along the roller axis39of the roller pin36and a normal component (not shown) exerted perpendicular to the roller axis39of the roller pin36. The tensioned string additionally exerts a vibratory force during the oscillatory movement of the string while the string is being played by a user. The vibratory force exerted through the roller axis39of the roller pin36is similarly resolved into an axial component (not shown) exerted along the roller axis39of the roller pin36and a normal component (not shown) exerted perpendicular to the roller axis39of the roller pin36. As the string12vibrates, the axial component of the vibratory force varies in magnitude and direction along the roller axis39. If, during oscillation of the string12, the axial component of the vibratory force opposes and exceeds the roller axis component142of the static force, the roller34and roller pin36will vibrate within the roller bore37along the roller axis38.

According to the present invention, the roller axis39is disposed with relation to the tensioned string12such that the component of the static force142directed along the roller axis39is generally greater than the component of the vibratory force directed along the roller axis29. This relationship of the component parts of the saddle assembly31prevents vibration of the roller34and roller pin36along the roller axis39.

Either experientially or by calculation of the relative values of the maximum oscillatory force to the static force, the roller axis is disposed at a oblique angle38determined to be sufficient to create a roller axis component142of the static force142that is generally greater than the component of the vibratory force directed along the roller axis29at any time during the oscillatory movement of the string12.

The roller angle38of preferred embodiments of the present invention includes oblique interior angles between about 3 degrees (3°) to about 30 degrees (30°) with respect to a referenced plane, either the support plane25or the string plane14. A roller angle of about 6 degrees (6°) has been determined to be the preferred roller angle for prototypes of the saddle roller assemblies of the preferred embodiments. At this preferred roller angle, the roller axis component142of the static force exerted along the roller pin36biases the roller pin36into the lower of the roller bores37. Since this bias is generally greater than the axial component of the vibratory force exerted along the roller pin36, the roller pin36remains seated in the lower of the roller bores37. This prevents vibration of the saddle roller34within the saddle block32. Advantageously, the roller axis component142created by a 6 degree (6°) roller angle does not significantly increase the amount of rotational friction generated by the roller pin36rotating with respect to the roller bores37. In more preferred embodiments of this invention, the saddle pin36is narrowed to reduce the total area of contact between the roller bore37and the saddle pin36and, thus, reduce the amount of rotational friction affecting the saddle roller34.

This novel feature and advantage of the tremolo mechanism of this invention is a significant improvement over the prior art roller systems. One skilled in the arts would appreciate that the invention includes roller bridge structures providing: a roller disposed so as to rotate around a roller axis; and a tensioned string exerting a static force on the roller and further exerting a vibratory force on the roller during oscillatory movement of such string, wherein, the roller axis is disposed with relation to the tensioned string such that the component of the static force directed along the roller axis is generally greater than the component of the vibratory force directed along the roller axis.

Referring now toFIGS. 5,6,8and9, the roller support assemblies31further include intonation adjustment structures which may be used to adjust the tone of the received strings12by displacing the saddle blocks32, and therefore the saddle rollers34, with respect to the support surface25.

One intonation adjustment structure shown is a saddle height screw40disposed in a threaded bore extending through the saddle block32. A portion of the saddle height screw40extends beyond the saddle block32and slidably engages the support surface25. In the preferred embodiment shown, the saddle block terminates in a screw cone point42which provides a reduced area of contact between the screw40and the support surface25. This reduced area of contact feature reduces any transmission of vibrations between the saddle block32and the base20and reduces frictional resistance as the saddle block32slides over the support surface25. As the saddle height screw40is rotated, the portion of the screw that extends beyond the saddle block32is adjusted and the distance between the received tensioned string12and the support surface25is changed by a proportional amount. Such displacement of the tension string12changes the pitch of the string.

One skilled in the art will readily recognize that the present invention includes any saddle height support generally known in the art, including saddle height supports that are not displaceable with respect to the saddle block32as well as those supports that are so displaceable.

Referring now toFIG. 6, the saddle block32of the first preferred embodiment of the present invention is shown extending towards the detuning pivot50along the support surface25. This extension of the saddle block32includes a saddle block foot48captured by a retaining channel27. Adjustment of the saddle height screw40of this preferred embodiment causes the saddle block32and saddle roller34to pivot in an arc of constant radius around the saddle block foot48. Thus, adjustment of the saddle height screw40of this preferred embodiment simultaneously causes displacement of the saddle block32longitudinally along the support surface25and displacement of saddle block32vertically above the support surface25.

The second preferred embodiment of the present invention is shown inFIGS. 5a,5b,8and9and includes an intonation screw44disposed in a threaded bore extending into a saddle block32. The intonation screw extends generally longitudinally from the saddle block32and is received by retaining channel26disposed in support surface25. The intonation screw44is terminated in a screw end sphere46which is shown disposed in a hemispherical seat in the retaining channel26. The intonation screw44pivots within the hemispherical seat as the screw is retracted or extended from the threaded bore of the saddle block32. As the intonation screw44is operated, it displaces the saddle block32longitudinally along the support surface25. The saddle roller34is displaced longitudinally with respect to the received tensioned spring12and the position of the vibratory end point along the length of the tensioned string12is adjusted accordingly. According to the present invention, the saddle height screw40and the intonation screw44may be operated independently or in combination as desired to adjust the pitch of the received tensioned string12.

One skilled in the art will readily recognize that the present invention includes such generally known intonation mechanism as may be used to longitudinally displace a saddle block with respect to the support plate or as may be used to adjust the height of a saddle block with respect to the support plate.

Referring now toFIGS. 8,11, and13, a detuning pivot50of a preferred embodiment of the tremolo mechanism10of the present invention is shown. With the lock110in an unlocked configuration, the frame60of the tremolo mechanism10freely pivots relative to the base20by means of the detuning pivot50as referenced above. The geometric relationships between the detuning pivot50and the support surface25and between the detuning pivot50and the string plane14are shown inFIG. 8. The portion of the detuning pivot50attached to the base20includes two base plates52attached to the base20and held in alignment by pivot alignment pin59. For each base plate52, a knife edge56extends from the base plate52along the detuning axis51, which is oblique with respect to the support surface25and which is also oblique with respect to the string plane14. In the embodiment shown, the plane defined by the support surface25is generally parallel to the string plane14and the detuning axis intersects both the plane defined by the support surface25and the string plane14at the same oblique detuning angle53. Referring now toFIGS. 11 and 13, the tailpiece frame60includes two frame plates54(one of which is not shown) attached to the frame60. For each frame plate54, a knife edge seat58extends from the frame plate54along the detuning axis51. Each knife edge seat58receives a knife edge56so as to form a knife edge pivot. As shown inFIG. 11, with the lock110in an unlocked configuration, the pair of aligned knife edges56form the detuning axis51about which the counter-spring53and the tensioned strings12of the instrument bias the tailpiece frame60.

Pivoting String Anchor

Referring now toFIGS. 5a,5b,6and7, the tremolo mechanism10of the present invention further includes a novel and advantageous pivoting anchor assembly70. For each tensioned string extending from the bridge30, a pivoting anchor assembly70provides for the continuous, rapid and near frictionless alignment of a knife edge pivot86, a string end anchor72holding a string end, and the string apex87in response to changes in the direction and magnitude of the tension force exerted along the tensioned string12, such changes created as the knife edge pivot86is displaced relative to the string apex87.

One preferred embodiment of the present invention shown inFIGS. 5a,5band7includes, for each tensioned string12extending from the bridge30, a pivoting anchor assembly70displaceably disposed upon a tuner arm91of a tuning assembly90. The pivoting anchor assembly70of the present invention includes a pivot support structure, a pivot and an anchor structure for receiving and holding an end of a tensioned string12. In the preferred embodiment shown, the pivoting anchor assembly70includes a rate screw73disposed in a threaded bore of the tuner arm91and extending there from so as to receive and support an anchor block71. The anchor block71includes a string end anchor72, a jaw opening77and further includes a knife edge76extending into the jaw opening77. An upper portion of the rate screw73includes a circumferential knife edge seat75. The upper portion of the rate screw73extends through the jaw opening77such that the knife edge76is received within the knife edge seat75, so as to form a knife edge pivot86. With the tremolo mechanism10installed on an instrument1, the string end anchor72of the anchor block71receives and holds an end of a tension string12. The knife edge pivot86allows the anchor block71with the string end anchor72to pivot both axially and radially relative to the rate screw73in response to changes in the magnitude and direction of the tension force exerted long the tensioned string12. The changes in the tension force bias the position of the anchor block71and string end anchor72so as to align the knife edge pivot86, the string end anchor72holding a string end, and the string apex87.

In alternate embodiments of the present invention, the anchor block71is supported by a pivot post fixedly extending from the tuning arm91. One skilled in the arts would recognize that the present invention includes pivot supports generally known in the art as useful for supporting a pivoting body above a base.

Each pivoting anchor assembly70of the preferred embodiment of the invention shown inFIG. 7includes a knife edge seat75adjustably disposed a first offset distance82from the tuner arm. With a string end received and held by the string anchor72, the anchor block71pivots about the knife edge seat75so as to align the string apex87at the bridge seat with the string anchor72and the knife edge pivot76. Operation of the rate screw to73to adjust the first offset distance82results in a displacement of the knife edge seat75and, thus, the pivoting anchor assembly70relative to the string apex87. This displacement tends to change tension forces in the string12which, in turn, changes the reactive bias exerted by the string12upon the string anchor72. Since alignment of the knife edge pivot86, the string anchor72and the string apex of the bridge seat minimizes the tension in the string12, the result is an automatic and continuous change in the pivot angle of the string end pivot70relative to the rate screw73so as to maintain the alignment of the knife edge pivot86, the string anchor72and the string apex of the bridge seat.

Each pivoting anchor assembly70of the preferred embodiment of the invention shown inFIG. 7also includes the knife edge seat75adjustably disposed at a second offset distance83from the tuner arm shaft92. Operation of the rate screw to73to adjust the first offset distance82will necessarily adjust the second offset distance83and result in a displacement of, the pivoting anchor assembly70relative to the tuner arm shaft92as well as relative to the string apex87.

Further, adjustment of the tuning assembly90so as to pivot the tuner arm91around the tuner arm shaft92provides a second mechanism for changing the position of the pivoting anchor assembly70relative to the string apex87. As shown inFIG. 2,5a,5bandFIG. 7the tuner arm91extends longitudinally through a channel61in the tailpiece frame60. A tuner nut94is disposed in a bore extending though the tuner arm91and receives a tuner screw93extending through a threaded bore within the tuner nut94. The tuner screw93extends though a threaded bore disposed in a tuner ball95, the tuner ball95being disposed within the tailpiece frame60so as to allow rotation of the tuner ball95without longitudinal displacement of the tuner screw93relative to the frame60. A tuner knob96is affixed to one end of the tuner screw93. Rotation of the tuner knob96by an operator rotates the tuner screw93so as to displace the tuner nut94along the length of the tuner screw93.

This linear displacement of the tuner nut94causes the tuner arm91to pivot about the tuner arm shaft92. As the tuner arm91pivots, it is displaced relative to the tailpiece frame60and, thus, relative to the string apex87. With the rate screw73disposed on the tuner arm91, operation of the tuner knob96rotates the knife edge seat75and, thus, the pivoting anchor assembly70about the tuner arm shaft92. Such rotational displacement of the pivoting anchor assembly70relative to the string apex87tends to change the tension forces exerted along the tensioned string12as described above, and results in an automatic and continuous change in the pivot angle of the string end pivot70relative to the rate screw73, so as to maintain the alignment of the knife edge pivot86, the string anchor72and the string apex of the bridge seat.

A third mechanism for changing the position of the pivoting anchor assembly70relative to the string apex is operation of the tremolo mechanism10as described above. The frame60and all its pivoting anchor assemblies70are rotated about the detuning axis51with respect to the base20. With a string end received and held by the string anchor72of each pivoting anchor assembly70, rotation of the frame60about the base20causes each anchor block71to pivot about its knife edge seat86so as to align the corresponding string apex87with the string anchor72and the knife edge pivot76.

An additional novel feature of the tremolo mechanism10of this invention includes the block retainer assembly88which limits the displacement of the knife edge76from the knife edge seat75. In the embodiment shown inFIG. 7the block retainer assembly88includes a retaining surface80disposed on the tuner arm91and further includes a trailing portion84of the anchor block71. The trailing portion extends towards the retaining surface80and is separated there from by a clearance distance79. The seat depth78is generally greater than the clearance distance such that displacement of the knife edge76from the knife edge seat75is limited by contact of the trailing portion84with the retaining surface80while maintaining the knife edge76within a portion of the knife edge seat75. Of note, the knife edge seat75is tapered so as to allow a wide range of angular displacement of the anchor block71about the knife edge pivot86and in longitudinal alignment with the rate screw. Further, in the preferred embodiment shown inFIG. 7, the knife edge seat75is circumferential with respect to the rate screw so as to allow the anchor block71to pivot radially relative to the rate screw73. In alternate embodiments of the present invention the knife edge seat75spans only a portion of the circumference of the rate screw73. In other alternate embodiments, the knife edge seat75is a linear channel disposed in the rate screw73.

Referring now toFIG. 6, a second preferred embodiment of the present invention is shown including a block retaining assembly88comprising a retaining spring85extending from the tuner arm91and engaging the anchor block71so as to bias the knife edge76against the knife edge seat.

Cam Actuated Tremolo Lock Providing Half Step Pitch Variations

The lock of the tremolo mechanism of the present invention includes fixed and movable subparts having opposing first and second engagement surfaces disposed thereon. Intermeshing ridges and channels are disposed on the first and second engagement surfaces such that the lock is selectably configurable in a plurality of configurations.

According to the present invention, with the lock disposed in an unengaged configuration, the first and second engagement surfaces are separated so as to allow the frame to pivot relative to the base. Such rotation of the frame causes the first engagement surface to be displaced transversely relative to the second engagement surface. In each of a plurality of engaged configurations, the first and second engagement surfaces are pressed together so as to prevent the frame from pivoting relative to the base.

Referring now toFIGS. 6,7and10-14, the tremolo mechanism10of a preferred embodiment of the present invention is shown including a lock110having a moveable locking arm111and a fixed locking block112. The movable locking arm112is disposed within the frame60and a plurality of parallel locking channels114are disposed on an engagement surface of the movable locking arm111. A locking ridge113is disposed upon the locking block112so as to be in aligned opposition with the locking channels114. In a more preferred embodiment of the present invention, the locking channels114and the locking ridge113are disposed so as to be parallel with the detuning axis51and the locking arm111is disposed on a torsion bar120that extends parallel to the detuning axis. This alignment is necessary to ensure the locking ridge113intermeshes with any locking channel113positioned for engagement with the locking ridge113.

A preferred embodiment of the present invention shown inFIG. 12illustrates the lock110of the present invention disposed in an unlocked configuration. The locking block112and the locking arm111are separated so as to allow the tailpiece frame60to pivot about the base20. With the lock110in a locking configuration, as shown inFIG. 14, the locking arm111is rotated towards the locking block112such that the locking ridge113is inserted into a locking channel114. The plurality of locking channels114are separated by a spacing distance115between the locking channels114. Thus, a plurality of locking configurations is available for selection by a user. Further, for each of the engaged configurations, the frame60is disposed at a selected angular displacement of the frame60about the detuning axis51and the first and second engagement are pressed together such that locking ridge113intermeshes with such channel114as corresponds to the selected angular displacement of the frame60.

A novel feature of the lock110of the tremolo mechanism10is illustrated in the preferred embodiment shown inFIGS. 6,7and10-14. The lock110is disposed at a portion of the frame60generally most distal to the detuning axis51and the locking channels114are separated by a spacing distance115such that transverse displacement of the locking arm111relative to the locking ridge113by a spacing distance115provides such angular displacement of the frame60about the detuning axis51as to cause a chromatic half step change in the pitch of each of the plurality of tensioned strings.

Moreover, each of the plurality of locking channels114provides a positive control of the locking ridge113against movement in either direction. The prior art provided only a single, central locking channel with spring-biased locking positions above and below the central locking channel. The prior art provided for a tuned equilibrium position only corresponding to a single locking channel. The novel lock110of the present invention allows the tuned equilibrium position to be set so as to correspond to any of the plurality of locking channels114. This provides the novel advantage of being able to shift the pitch of each of the plurality of tensioned strings12in chromatic half steps as the tremolo mechanism10is shifted between sequential locking configurations corresponding to locking channels114above and/or below the locking channel114selected for equilibrium tuning.

Alternate embodiments of the present invention provide for the plurality of parallel channels disposed on the locking block and the locking ridge disposed on the locking arm. One skilled in the arts would recognize that the novel and advantageous lock of the present invention includes locks having first and second engagement surfaces that include opposing interlocking features which, on at least one such engagement surface, are interspaced by a spacing distance and which align and interlock at selected transverse displacements of the first and second engagement surfaces. Further, such transverse displacement of the first engagement surface relative to the second engagement surface by such a spacing distance provides such angular displacement of the frame about the detuning axis so as to cause a chromatic half step change in the pitch of each of the plurality of tensioned strings.

Referring again toFIGS. 10 and 11, the lock110of the preferred embodiment shown further includes a locking spring116connected at one end to the frame60and is held in place by tail pin117. At its other end, the locking spring116is connected to the locking arm111and biasing the locking arm111away from the locking block112so as to place the lock110in an unengaged configuration.

The user can position the lock110in either the unengaged position or in any of the plurality of engaged positions by using a tremolo arm100to pivot tailpiece frame60to the desired radial angle of rotation with respect to the detuning axis51and then rotating the tremolo arm110so as to operate a cam actuator103to position a torsion bar120connected to the locking arm111, so as to engage or disengage the locking arm111, from the locking block112.

The tremolo arm100is connected to a release cam103as shown inFIGS. 13 and 14. A threaded portion of the tremolo arm100is disposed in a threaded bore of the cylindrical body104of the release cam103. The tremolo arm100is secured in place by means of an arm nut101threadably fastened on the tremolo arm100, so as to prevent disengagement of the tremolo arm100from the cylindrical body104. The release cam103further includes the cylindrical body104upon which a cam profile105is positioned.

Referring now toFIGS. 4,10and11, the cam profile105shown includes an actuation seat107connecting an unlocked seat106with a locked seat108. The tremolo mechanism10is shown in an unengaged configuration with a cam follower109received in the unlocked seat106. The cam follower109is disposed upon one end of a torsion bar120. The unlocked seat106is disposed at a first constant radius with regards to the axis of the cylindrical body104. The locked seat108is disposed at a second constant radius with regards to the axis of the cylindrical body104. The actuation seat107has a radius increasing from the first radius to the second radius as the actuation seat107spans from the unlocked seat106to the locked seat108. The torsion bar120is connected at its other end to the locking arm111. The locking arm111is not directly connected to the frame, thus the locking spring116supports and biases both the locking arm111and the torsion bar120that extends from the locking arm111such that the cam follower109is biased against the cam profile105.

The rotation of the tremolo arm100to place the lock110in an engaged configuration rotates the cam profile105beneath the cam follower109from the unlocked seat106to the locked seat108. The cam follower109is displaced radially from the first radius to the second radius. This radial displacement produces a lateral displacement of the torsion bar120and the locking arm111so as to engage a selected locking channel114with the locking ridge113. Such radial displacement further produces a loading torque on the torsion arm120which is reactively transferred to the locking arm111so as to hold and secure the locking arm111against the locking block112.

Referring again toFIGS. 4,10and11, the preferred embodiment of the tremolo mechanism10is shown in the unengaged configuration with the tremolo arm100extending over the frame60and generally parallel with the tensioned strings12. In this position, the tremolo arm100is a lever providing a mechanical advantage to the user in rotating the frame60about the base20. Referring now toFIGS. 13 and 14, the preferred embodiment of the tremolo mechanism10is shown in an engaged configuration with the tremolo arm100rotated to a position extending away from the tailpiece frame60in a direction generally perpendicular to the tensioned strings12, so as to remove the tremolo arm100from the play of the tensioned strings12by the user. In this position, the tremolo arm100provides no mechanical advantage to the user in rotating the frame60about the base20. If desired, with the lock110in an engaged configuration, the tremolo arm nut101can be loosed and the tremolo arm100removed from the mechanism.

A second novel feature of the lock110of tremolo mechanism10is the unique combination of the radial spans of the unlocked seat106, actuation seat107and locked seat108. According to the present invention, the actuation seat107spans a radial angle of between about ten degrees (10°) and about thirty degrees (30°) with respect to the cylinder axis. The preferred span of the actuation seat107of the embodiment of the present invention illustrated inFIG. 4is a radial angle of about twenty three degrees (23°) with respect to the cylinder axis. Moreover, the locking arm111engages the locking block112when the cam follower109is disposed on the actuation seat107at greater than eight degrees (8°) from the unlocked seat106. According to the present invention the locked seat108spans a radial angle of at least about twenty five degrees (25°) with respect to the cylinder axis. The preferred span of the locked seat108of the embodiment of the present invention illustrated inFIG. 4is a radial angle of about seventy two degrees (72°) with respect to the cylinder axis. According to the present invention the unlocked seat106spans a radial angle of between about twenty degrees (20°) and about sixty degrees (60°) with respect to the cylinder axis. The preferred span of the unlocked seat106of the embodiment of the present invention illustrated inFIG. 4is a radial angle of about forty degrees (40°) with respect to the cylinder axis. Advantageously, the combination of the radial spans of the actuation seat107and locked seat108provides for actuation of the lock110over a short arc of operator motion and further provides for a positioning of the tremolo arm well out of the area of play once the lock is engaged. Also, by restricting the radial span of the unlocked seat106, the tremolo arm100may be restricted to extending in a direction generally over the detuning axis so as to provide an effective lever for operating the tremolo mechanism10to creating a vibrato effect.

The cam actuated lock of the present invention accommodates misalignments by the user by means of a third novel feature of the present invention shown inFIGS. 11 and 14. The locking channels114of the locking arm111are separated by lands which are shaped to direct the locking ridge113towards a locking channel114if the locking ridge113first contacts a land beside a locking channel114during in the locking process. The torsion arm120shown provides a flexible means of applying a motive force for moving the locking arm111into a locked configuration. According to the present invention if the locking ridge113and a selected locking channel114are misaligned and the cam cylinder104is rotated such that the cam follower109is disposed upon the locked seat108, the torsion bar120elastically deforms as the locking ridge113is received by a land between the locking channels114without damaging the lock110. Further, any additional transverse movement of the locking arm111relative to the locking block112causes the locking ridge113to slide across the land and seat in an adjacent locking channel114. Prior art locking mechanisms have rigid mechanical connections that, if misaligned during locking, would either be damaged or would fail to lock. Advantageously, the cam actuated lock of the present invention accommodates misalignments by the user without neither damage to the lock nor failure to lock.

As can be readily seen by those skilled in the art, various modifications and variations could be made in the tremolo mechanism of the invention without departing from the scope or spirit of the invention.

Thus, although there have been described particular embodiments of the present invention of a new and useful Tremolo Mechanism for a Stringed Musical Instrument it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.

Thus, although there have been described particular embodiments of the present invention of a new and useful Tremolo Mechanism For A Stringed Musical Instrument With Pivoting String Anchor, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.