# Patent

## Title
Pitch adjustment device for stringed musical instruments

## Abstract

A pitch adjustment device for selectively adjusting the pitch of multiple strings of a stringed musical instrument from the open pitch (normal unadjusted pitch) while playing using a single lever, wherein the tension and pitch of different strings can be adjusted by different and adjustable amounts for each adjustable string. The device comprises a support frame configured to be mounted onto the stringed musical instrument and a string puller rotatably coupled to the support frame and rotatable about a first axis. At least two pitch adjusters are attached to the string puller. Each pitch adjuster has a string support for securing a respective adjustable string and is adjustable to adjust the respective string support to a plurality of different radial positions from the first axis. A lever coupled is the string puller such that pivoting the lever rotates the string puller relative to the frame about the first axis.

## Background
FIELD OF THE INVENTION
The field of the invention generally relates to stringed musical instruments, and more particularly to a device for selectively adjusting the tension (and therefore pitch) of the strings of such musical instruments while the instrument is being played.
BACKGROUND OF THE INVENTION
In general, stringed musical instruments commonly comprise a body having a first end with a support for attaching one end of the strings, a second end having a support for attaching the other end of the strings and a tuning apparatus for adjusting the tension, and thus the pitch, of each of the strings. As one example, a steel guitar is a generally horizontally mounted guitar having a head end and a tail end and a plurality of strings extending therebetween. The head end is provided with a plurality of tuning keys (one for each string) to which one end of a string is secured. The tuning keys allow manual adjustment of the pitch of each string to tune the guitar. The other end of the string is secured to a bridge at the tail end of the guitar.
In addition, stringed instruments such as guitar, steel guitars, and the like, typically have more than one possible tuning. A “tuning” of a stringed instruments means the pitches assigned to the open pitch (the fundamental pitch of the properly tuned, unstopped, full string) of each of the strings on the stringed instruments. For example, the standard tuning, which is the most common tuning, of a standard, six string guitar, from lowest pitch string (top string in standard orientation of guitar) to highest pitch string (bottom string) string is E-A-D-G-B-E. However, there are a number of “alternate” tunings. For example, “drop tunings” begin with the standard tuning and then lowers (“drops”) the pitch of only a single string, or in rare cases, two strings. The dropped stringed is usually the lowest pitched (E) string, such as in the “drop D tuning” in which the lowest string is tuned down a whole step to a low D. Other alternate tunings are referred to as “open tunings” in which the open pitch of all six strings play a chord. For instance, the major open tunings give a major chord with the open strings, such as “Open A,” “Open B,” etc.
Steel guitars are generally not tuned in standard guitar tuning, but instead are tuned to an open chord, and have many, many popular tunings. The most common 6-string steel guitar tuning is the C6 tuning, which in itself has no “standard”, but rather has a number of variations. One popular C6 tuning is C-E-G-A-C-E, from lowest pitch (closest to the musician in the standard playing position) to highest pitch (furthest from the musician). All tunings shown herein are from lowest pitch to highest pitch, i.e. from thickest string to thinnest string. Several alternate tunings for steel guitar include: Open E tuning—E-B-E-G#-B-E; Open A tuning—E-A-E-A-C#-E; Open G tuning—D-G-D-G-B-D; to name a few among many more.
In the course of playing certain stringed instruments, in particular a steel guitar, a musician may desire to produce characteristic effects, and/or change the overall tuning of the instrument, by changing the pitch of one or more selected strings by adjusting the tension of the particular string(s), rather than by modifying the vibrating length of the string(s) by “fingering” on a fret board or placing a movable slide (or “tone bar” or “fret bar”) along the string(s). Changing the pitch of just selected strings allows the musician to expand the amount of tonal and chordal variation available to the musician in playing the stringed instrument.
While the tuning keys provide for relatively convenient tuning of the “open pitch” (the fundamental pitch of the properly tuned, unstopped, full string) of each string, musicians often desire to modify the open pitch of one or more strings while playing the instrument. The tuning keys are not convenient for adjusting the pitch of a string while playing for a variety of reasons. For one, the keys are not located in a convenient location for the musician to adjust manually because the musician is generally using both hands to play the instruments, with one hand strumming or plucking the strings and the other hand manipulates the strings to adjust their pitch to form desired tones. In addition, the tuning keys do not allow for a calibrated or consistent adjustment of pitch to an adjusted pitch, or consistent return to the original open pitch, but instead both changes in pitch vary with the amount of manual rotation of the key which is inherently imprecise as it depends on the manual precision of the musician.
In the past, various pitch adjusting mechanisms for adjusting the pitch of select strings of a stringed musical instruments while playing the instrument have been proposed. These pitch adjusting mechanisms generally operate by selectively increasing or decreasing the tension or pitch of a string by moving one of the secured ends of the string to either decrease the vibrating length of the string (which increases the tension and raises the pitch) or increase the vibrating length of the string (which decreases the tension and lowers the pitch). Although not limited to steel guitars, these types of pitch adjusting mechanisms have found widespread application on steel guitars.
Typical examples of pitch adjusting mechanisms for adjusting the pitch of strings on string instruments while playing, such as a steel guitar, are found in U.S. Pat. No. 3,688,631 and U.S. Pat. No. 3,390,600. These patents are expressly incorporated by reference herein in their entireties. Each of these patents discloses a pitch adjusting mechanism for adjusting the pitch of an individual string both upwardly or downwardly. The mechanisms in both of these two patents also have in common that the pitch adjusting mechanism is provided at the bridge end of the strings and the mechanisms comprise relatively complicated systems of levers, springs and linkages. In order to provide for both raising and lowering the pitch of the string with a single lever attached to the string, these mechanisms provide for a system which allows the single lever to be selectively actuated in both directions, i.e. clockwise and counter-clockwise, and also provide a means for returning the string to the open tune position (this means the normal pitch of the string without actuation of the pitch adjusting mechanism) upon de-actuation. Accordingly, the springs and lever arms of each of the parts of these mechanisms must be delicately balanced to provide proper operation and to minimize or avoid mis-tuning.
However, none of the prior pitch adjusting mechanisms allow for a simple, individually operated actuator which can adjust the pitch of multiple strings each by differing and modifiable amounts. In other words, none of the prior devices provide a simple mechanism which can adjust a first string by one amount which is modifiable, and another string by a different amount which is independently modifiable from the first string, by the operation of a single actuator, such as a single lever or pedal. For example, adjusting a steel guitar from one tuning to a different tuning may require adjusting one string a whole tone, while adjusting another string by a half tone (the term “note” is used interchangeably herein with the term “tone” when referring to the musical scale).
Therefore, there is need for a pitch adjustment device for stringed instruments which overcomes the problems associated with prior devices.
SUMMARY OF THE INVENTION
The present invention is directed to an innovative pitch adjustment device (also referred to as an apparatus) for selectively adjusting the pitch of multiple strings of a stringed musical instrument from the open pitch (normal unadjusted pitch) while playing using a single lever, wherein the length of different strings (and thus tension and pitch) can be adjusted by different and adjustable amounts for each adjustable string. Accordingly, the device allows a musician to adjust the pitch of two or more strings, wherein the amount of pitch adjustment of each string can be adjustably preset independent of the other strings. In other words, a first string can be preset to adjust the pitch of the first string from the open position to an adjusted pitch which is a whole tone different from its open tone, while a second string is preset to adjust the pitch of the second string from the open position to an adjusted pitch which is a half tone different from its open tone, with both strings being adjusted by a single actuation of a single lever. The device provides for very stable and consistent pitch in the adjusted and open pitch of each string, while also providing relatively simple tuning adjustment for each pitch position. In other words, it is a straightforward and simple task to tune each string to provide the desired open pitch, and the adjusted pitch in the actuated position.
In one embodiment, the pitch adjustment device comprises a support frame configured to be mounted onto a stringed musical instrument. For instance, in the case of a use on a steel guitar, the support frame is configured to be mounted to the top of the body or frame of the steel guitar. The support frame may be configured to function as the bridge located at the tail end of a steel guitar, for example. The pitch adjustment device further comprises a string puller rotatably coupled to the support frame and rotatable about an axis of rotation (e.g., a first axis). Typically, the axis of rotation of the string puller is configured to be substantially transverse to the longitudinal axis of the strings of the musical instrument, when the device is mounted on the stringed instrument.
At least two pitch adjusters are attached to the string puller at spaced apart locations such that each pitch adjuster rotates with the rotation of the string puller. One pitch adjuster is provided for each string which will have its pitch adjusted by the device (referred to as an “adjustable string”). Thus, two pitch adjusters are provided to adjust two strings, three pitch adjusters are provided to adjust three strings, and so on. Typically, each pitch adjuster is located on the string puller in alignment with the respective string which it will adjust. The strings which do not have their pitch adjusted by the device, if any, are fixed in place, such as attached to a fixed bridge portion of the frame.
Each pitch adjusters has a string support for securing a respective adjustable string of the stringed instrument at a respective string position for each pitch adjuster. Each pitch adjuster is adjustable to adjust the respective string support to a plurality of different radial positions from the first axis. Said another way, each pitch adjuster can vary the radial distance of the string support, and therefore the tail end of the string, from the first axis. Accordingly, the distance traveled by the string support for a given rotation of the string puller is proportional to the radial distance of the string support from the first axis. Hence, for a given rotation of the string puller, a first pitch adjuster having its string support at a first radius will modify the length of its respective string by a greater amount than a different pitch adjuster having its string support at a second radius smaller than the first radius.
A lever is coupled to the string puller such that pivoting the lever rotates the string puller relative to the frame about the first axis. The lever is typically attached to one end of the string puller and is located near the palm of the musician and oriented longitudinally substantially parallel to the strings when the device is mounted on the instrument. The lever has a normal position in which the lever is not being actuated (i.e., the adjustable strings are in the open pitch) and an actuated position in which the lever is pivoted in a first direction from the normal position (i.e., the adjustable strings are in an adjusted pitch).
The operation and use of the pitch adjustment device is fairly straightforward. The pitch adjustment device is mounted to a stringed instrument, such as at the tail end of a steel guitar. The tail end of the adjustable strings are secured to the string supports of their respective string adjusters. With the lever in the normal position (typically, the lever is biased to the normal position by the string tension and/or counterbalancing springs), the instrument is tuned to the open tuning with each string tuned to its open pitch. Then, the lever is actuated by pivoting the lever in the first direction (usually downward) to the actuated position. The adjustable strings are then tuned to the desired adjusted pitch by adjusting the string adjusters thereby adjusting the radial distance of the string supports. As explained above, the amount of pitch adjustment applied by each pitch adjuster to its respective string can vary from one adjustable string to another.
The pitch adjustment device can then be utilized by a player while playing the instrument. To play the instrument with the adjustable strings in their open pitch, the player simply leaves the lever in the normal position. When the player desires to modify the pitch of the adjustable strings, such as to change the tuning of the instrument from one key to a different key, the player actuates the lever to the actuated position by pivoting the lever in the first direction which rotates the string puller, the pitch adjusters, the string supports and the tail end of the adjustable strings, thereby modifying the length, and thus the tension and pitch, of the adjustable strings. When the player desires to return to the open tuning of the instrument, the player releases the lever, and the biasing force pivots the lever back to the normal position which in turn rotates the string puller, the pitch adjusters, the string supports and the tail end of the adjustable strings to their unadjusted position for the open tuning of the instrument.
In another aspect, the pitch adjustment device may further comprise an adjustable open stop for setting the position of the lever in the normal position, and/or an adjustable actuation stop for setting the actuated position of the lever at which the pivoting motion of the lever is limited (i.e. stopped).
In still another aspect, the string puller may comprise an elongated shaft having a pair of circular bearing surface, one on each end of the shaft. Each circular bearing surface is received in a respective circular hole in the support frame. The string puller may then rotate about the first axis by the circular bearing surface rotating relative to the respective circular holes in the support frame.
In an alternative aspect, the string puller may comprise a substantially flat, elongated plate. The plate has a plurality of pivot members, such as one on each end of the plate which bear against a respective pivot surface on the support frame such that the first axis is defined by the interface of the pivot members and the respective pivot surfaces. For instance, the pivot members may be sharp or knife edges which bear against their respective pivot surfaces such as an arcuate wall of the frame member.
In still another aspect, the pitch adjusters may each comprise a screw threadingly attached to a respective threaded hole in the string puller. In such case, the radial position of the string support can be adjusted by turning the screw.
In another feature of the present invention, the pitch adjusting device may further comprise one or more counterbalancing springs coupled to one of the string puller or the lever and configured to bias the rotation of the string puller against the tension of the strings when secured to the string supports.
In yet another aspect, a releasable locking device may be provided to releasably lock the lever in the actuated position. For example, the releasable locking device may be any suitable latch, magnets, fastener, detent, cam follower, pen click type mechanism, etc., for releasably locking the lever in the actuated position. If the adjustable open stop and/or an adjustable actuation stop for setting stops are installed on the bottom of the instrument, which is the case on certain designs, the lever can be independently adjusted, height-wise. Screws will adjust the height of the lever up or down, without effecting the position of the shaft. In others words, the player will not have to retune if the player adjusts the height of the lever.
In yet another feature, the device of the present invention may comprise two of the pitch adjusting devices as described above. Each pitch adjusting device includes each of the features described above, and are configured such that the axis of rotation of one of the string puller or one of the pitch adjusters is spaced apart from the axis of rotation of the string puller of the other pitch adjuster. In addition, the lever of one of the devices may be on the opposite side of the lever of the other pitch adjuster, so that one lever is located on one side of the strings of the stringed instrument and the other lever is located on the opposite side of the strings. Then, certain string(s) are secured to string support(s) on one of the device and different string(s) are secured to string support(s) on the other device. Then, after tuning both devices as described above, any combination of none, one or both devices can be actuated while playing to obtain a desired tuning of the instrument.
Additional aspects and features of the pitch adjustment device and related mechanisms of the present invention will become apparent from the drawings and detailed description provided below.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numbers refer to similar elements, and in which:
FIG. 1 is a side perspective view of an exemplary steel guitar having a pitch adjustment device, according to one embodiment of the present invention.
FIG. 2 is an enlarged partial side perspective view of the steel guitar and pitch adjustment device of FIG. 1;
FIG. 3 is an enlarged side view of the steel guitar and pitch adjustment device of FIG. 1;
FIG. 4 is a side perspective view of an exemplary steel guitar having a pitch adjustment device, according to another embodiment of the present invention;
FIG. 5 is an enlarged partial side perspective view of the steel guitar and pitch adjustment device of FIG. 4;
FIG. 6 is an enlarged side view of the steel guitar and pitch adjustment device of FIG. 4;
FIG. 7A-7C are an enlarged side view. an enlarged front view and an enlarged top view of an alternative plate design for a pitch adjustment device, according to still another embodiment of the present invention;
FIG. 8A is an enlarged top view of a string extender which can be used with the pitch adjustment devices, according to yet another embodiment of the present invention;
FIG. 8B is an enlarged side view of the string extender of FIG. 8A;
FIG. 8C is an enlarged side view of a pitch adjuster screw for use with the string extender of FIGS. 8A and 8B;
FIG. 9 is an enlarged side perspective view of a steel guitar having two pitch adjustment devices, according to another embodiment of the present invention.



DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, the pitch adjustment device 12 of the present invention will be described in connection with an exemplary instrument, in this case a steel guitar 10. It should be understood that the pitch adjustment device 12 and other related features are not limited to a steel guitar 10 as shown and described, but can be applied to any stringed instrument. Therefore, the present invention is not limited to the embodiment on a steel guitar. Moreover, although the steel guitar 10 is shown with a single neck, it is common for steel guitars to have two necks, a front neck and a rear neck, as shown in U.S. Pat. No. 3,688,631. It should be understood that the present invention can easily be applied to both necks of a dual neck steel guitar.
The steel guitar 10 comprises a body 14 having a head end 15 and a tail end 18, and a plurality of strings 20 (in this example, the steel guitar 10 has 6 strings) generally indicated at 20. The head end of each string 20 is operatively coupled to a respective tuning key 16. The tuning keys 16 are operably attached to a key frame 14, such that each tuning key 16 can rotate relative to the key frame 14 to adjust the tension, and thus pitch, of its string 20. The strings 20 extend rearward from the tuning keys 16 and pass over and are supported by the bridge 17. The tail end of each string 20 is operatively coupled to the pitch adjustment device 12 which is attached to the tail end 18 of the body 14. The pitch adjustment device 12 may be attached to the tail end 18 of the body 14 by any suitable fastening mechanism, such as screws, bolts, press fit, adhesive, bonding, etc. In addition, the individual components of the pitch adjustment device 12 may be individually attached to the body 14, or they may be attached to one or more structural elements which are attached to the body 14.
Turning to FIGS. 2 and 3 showing an enlarged view of the pitch adjustment device 12 and just the tail end 18 of body 14, the pitch adjustment device 12 comprises a support frame 22. The support frame 22 includes a pair of puller mounts 24, one located on the bottom side of the strings 20 and one located on the top side of the strings 20 (the top side of the instrument is the side furthest from the musician while playing the instrument in its normal orientation and the bottom side is the side closest to the musician). The puller mounts 24 extend upward away from the body 14 and are configured to rotatably support a string puller 26. The puller mounts 24 may be attached to a base plate 28 as shown in the embodiment of FIGS. 1-3, or they may be attached directly to the body 14 of the steel guitar 10.
The string puller 26 is rotatably coupled to the puller mounts 24 with one pillar mount 24 disposed on each end of the string puller 26. The string puller 26 has a longitudinal first axis 27 about which the string puller 26 rotates and which is substantially transverse to the longitudinal axis of the strings 20.
In the embodiment of FIGS. 1-3, the string puller 26 comprises an elongated, substantially circular shaft 30. The shaft 30 may have a plurality of notches 28 in the bottom surface of the shaft with each notch 28 located in alignment with a respective string 20. The shaft 30 may have any suitable alternative cross-sectional shapes, such as square, rectangular, etc. The string puller 26 has a circular bearing surface 33 on each end of the shaft 30 which is received in a respective circular bearing hole 35 (e.g. bearing race) in the puller mounts 24.
A plurality of adjustable pitch adjusters 32 are attached to the string puller 26 and located in alignment with a respective string 20. The pitch adjusters 32 are threaded screws which are threaded into a mating threaded hole in the shaft 30 of the string puller 26. Each pitch adjuster 32 has a string support 34 configured to secure the tail end of its respective string 20 for which the respective pitch adjuster 32 will adjust the tension and pitch. In the embodiment of FIGS. 1-3, the string support 34 is a pin sized and configured to receive and secure a ball end of the guitar strings 20. For convenience, most guitar strings are provided with a ball having a hole attached to the tail end of the string which can be quickly and easily secured to a pin or slot at the tail end of a guitar.
Each pitch adjuster 32 is attached to the string puller 26 in a substantially vertical orientation, in other words, substantially perpendicular (transverse) to the longitudinal axis of the both the string and first axis. In this position, the pitch adjusters 32 can adjust the length of their respective strings 20 a maximum amount for a given rotation of the string puller in either a clockwise or counterclockwise direction (the direction of rotation referenced facing the bottom end (closest to the musician) of the string puller 26). The pitch adjusters 32 may be attached to the string puller 26 in other suitable orientations, as required by the particular configuration and desired amount of pitch adjustment.
As shown in the example embodiment of FIGS. 1-3, three strings 20 are secured to respective pitch adjusters 32 (the “adjustable strings”), and three strings 20 are not secured to a pitch adjuster 32 (the ‘non-adjustable strings”). In typical use, a musician will not desire to adjust all strings 20 of an instrument while playing, such as steel guitar 10, but will only want to adjust a few strings, such as two strings, three strings, four strings, or sometimes more for instruments having more than six strings, such as a ten string steel guitar, etc. For the non-adjustable strings 20 (i.e. strings not attached to a pitch adjuster 20), the pitch adjustment device 12 may also include one or more string holders for securing the tail end of the non-adjustable strings 20. For example, in the embodiment of FIGS. 1-3, the pitch adjustment device 12 has a string holder 34 having a plurality of slots 36 for securing the tail end of the strings 20 (e.g. the ball end is simply inserted under the slot 36 with the string 20 extending up through the slot 36).
The pitch adjusters 32 are configured to adjust the amount of pitch adjustment for a given rotation of the string puller 26 by adjusting the radius of the respective string support 34 from the first axis 27. The radius of a string support 34 is easily adjusted by simply turning the screw in the direction to move the string support 34 in the desired direction, either increasing its radius or decreasing its radius. The change in length of a given string 20 (and thus the tension and pitch) caused by the rotation of the pitch adjuster 32 and string support 34 as a result of the rotation of the string puller 26 is determined by distanced the string support 34 move which is related to the radius of the string support 34 from the first axis 27. Accordingly, the amount of length adjustment for an adjustable string 20 can be adjusted by modifying the radial distance of the string support 34 from the first axis 27. Increasing radial distance increases the amount of adjustment afforded by a pitch adjuster 32 and decreasing the radial distance decreases the amount of adjustment afforded by a pitch adjuster 32, for a given rotation of the string puller 26. Therefore, the pitch adjuster 32a having its string support 34 at a first radius will modify the length of its respective string 20 by a greater amount than pitch adjuster 32b having its string support at a second smaller radius, and vice versa. Thus, the pitch adjustment device 12 allows different strings to be adjusted by different and adjustable amounts by the rotation of a single string puller 26 which is actuated by a single lever as described below. It is to be understood that the pitch adjusters 26 may have alternative configurations to the screw for supporting and adjustably moving the string support 34, such as a rod and detents, a rod and a ratcheting catch, etc.
Each pitch adjuster 32 may also be configured to either increase the length of its respective adjustable string 20 (i.e. increase the tension and pitch) or decrease the length of its respective adjustable string 20, for a given actuation rotation of the string puller 26 (e.g. the embodiment of FIGS. 1-3 is configured for a counterclockwise actuation rotation). In order to increase the actuated length, the string support 34 is positioned below the string puller 26 and to decrease the actuated length, the string support 34 is positioned above the string puller 26. For a clockwise actuation rotation, the opposite is the case.
A lever 38 is coupled to the string puller 26 for actuating the string puller 26 by pivoting the lever which rotates the string puller 26 about the first axis relative to support frame 22. The lever 38 is attached to the bottom end of the string puller 26, such as by an extension of the bearing surface 33 being received in a circular hole 40 in the lever 38. The lever 38 is positioned near the location where the palm of a musician would be while playing the instrument with an extension part extending from the connection to the string puller 26 substantially parallel to the strings 20. The lever 38 is shown in it normal position (un-actuated) and is actuated by pushing down on the extension part of the lever 38 causing the lever 38 to pivot in a counterclockwise direction to its actuated position, thereby causing the string puller 26, pitch adjusters 32 and string supports 34 to rotate counterclockwise, which adjusts the tension and pitch of the adjustable strings 20.
The pitch adjustment device 12 also comprises an adjustable actuation stop 42 for adjustably setting the actuated position by limiting the amount of pivoting of the lever 38 in the counterclockwise direction when actuated. The adjustable actuation stop 42 comprises a screw threaded into the lever 38 on the left side of the connection to the string puller 26 and extending out of the bottom of the lever 38 such that the bottom end of the hits a strike plate (e.g. base plate 28 or other plate) on the body 14 and stops the pivoting of the lever 38 in the actuated position. The actuated position of the lever 38 is adjusted by screwing the screw into or out of the lever 38 to set the desired actuated position for the lever 38.
An adjustable open tuning stop 44 is also provided to set the position of the lever in the normal position by limiting the pivoting movement of the lever in the clockwise direction. The adjustable open tuning stop 44 comprises a screw threaded into the lever 38 on the right side of the connection to the string puller 26 and extending out of the bottom of the lever 38 such that the bottom end of the hits a strike plate (e.g. base plate 28 or other plate) on the body 14 and stops the pivoting of the lever 38 in the normal position. The normal position of the lever 38 is adjusted by screwing the screw into or out of the lever 38 to set the desired normal position for the lever 38.
One or more counterbalancing springs 46 are provided to counteract the forces (including torque) on the pitch adjusters 32, string puller 26 and lever 38 caused by the tension of the adjustable strings 20 being attached to the pitch adjusters. In the embodiment of FIGS. 1-3, the counterbalancing springs 46 are tension springs (i.e. the spring is in tension and the ends pull toward the center of the spring) with a first end coupled to a respective pitch adjusters 32 and a second end coupled to a spring support 48 which is mounted to the body 14 of the steel guitar 10. The first end of each of the counterbalancing springs may be coupled to its respective pitch adjusters 32 by a loop on the first end being received on the pitch adjuster 32. The second end of each of the counterbalancing springs may be attached to the spring support 48 using a screw or other attachment device. The amount of counterbalancing force may be adjusted by adjusting the screw to increase or decrease the length and force of the counterbalancing springs 46.
Alternative to the springs 46 comprising one or more tension springs, or in addition, the device 12 may utilize a lever counterbalance 50 comprising a compression spring 49 coupled to the lever 38 to counteract the tension of the adjustable strings 20. The compression spring 49 positioned on the right side of the connection of the lever 38 to the string puller 26. The compression spring 48 is inset into the body 14 and an adjustment screw 51 is threaded into the lever 48 and extends out of the bottom of the lever 38 and bears on the compression spring 49. The amount of counterbalancing force may be adjusted by adjusting the adjustment screw 51.
The counterbalancing springs 46 and/or lever counterbalance 50 are adjusted so that there is a net force from the string tension biasing the lever 38 and spring puller 26 to the normal position, such that upon release of the lever 38 when in the actuated position, the lever 38 and spring puller 26 return to the normal position by the net force.
The lever 38 may also have a releasable locking device 52 for releasably locking the lever 38 in the actuated position. The releasable locking device 52 may be any suitable latch, magnet, fastener, detents, cam follower, pen click mechanism, or the lock for releasably locking the lever 38 in the actuated position. For example, a pen click mechanism can be pushed once to lock the lever 38 in the actuated position, and upon pushing the lever a second time, the pen lock mechanism releases the lever 38 so it returns to the normal position. The locking device 52 may alternatively be a detent or latch in which the lever 38 may pivotable (e.g. may be swiveled) about an axis perpendicular to the first axis 27, such as a vertical axis in the orientation of the lever in FIGS. 1-3. In other words, the lever 38 can be swiveled toward and away from the player about the vertical axis. In one way, the lever 38 may be attached to the string puller 26 by a ball and socket joint with a vertical pin retaining the ball in the socket and the vertical pin defining the vertical axis about which the lever 38 can swivel. The lever 38 is provided with a latch or detent and the body 14 of the guitar 10 is provided with a mating catch. In operation, the lever 38 is pivoted to the actuated position with the lever 38 in an unswiveled orientation about the vertical axis. With the lever 38 in the actuated position, the lever 38 is swiveled about the vertical axis (either toward or away from the player, depending on the configuration of the latch and catch) to mate the latch or detent on the lever 38 with the mating catch on the body 14. This locks the lever 38 in the actuated position. Then, to release the lever 38, the lever 38 is simply swiveled in the opposite direction to release the latch from the catch, and the lever 38 returns to the normal position by the biasing force as described herein.
The operation of the pitch adjustment device 12 will now be described. The steel guitar 10 and pitch adjustment device 12 must first be tuned to the proper open tuning and adjusted tuning (tuning with the device 12 actuated). First, each of the strings 20, including the adjustable strings 20, are tuned to their desired open pitch with the lever in the normal position. The string 20 which requires the least amount of length adjustment in order to adjust the string's pitch from the open pitch to the adjusted pitch is tuned for the adjusted pitch first (referred to as the first adjustable string). The tuning is facilitated by having the pitch adjuster 32 for such string 20 set with its string support 34 at its minimum radial distance from the first axis 27 (in other words, the string support 34 is positioned closest to the spring puller 26). Then, with the lever 38 pivoted to the fully actuated position set by the adjustable actuation stop 42, and the adjustable actuation stop 42 is adjusted to tune the first adjustable string 20 to its desired adjusted pitch (i.e. adjusting the adjustable actuation stop adjusts the amount of rotation of the pitch adjuster 32 for the first adjustable string thereby adjusting the pitch). Next, the second adjustable string 20 which requires more length adjustment to go from its open pitch to its adjusted pitch is tuned to its desired adjusted pitch with the lever 38 in the actuated position as just set while tuning the first adjustable string. The second adjustable string 20 is tuned by adjusting the radial distance of its respective string support 34 to tune the second adjustable string 20 to its desired adjusted pitch. Any additional adjustable string 20 are tuned in the same manner as the second adjustable string 20.
Now, the steel guitar 20 is ready to be played utilizing the pitch adjustment device 12. To play the steel guitar 10 with the adjustable strings 20 in their open pitch, the player simply leaves the lever 38 in the normal position. When the player desires to modify the pitch of the adjustable strings 20, such as to change the tuning of the steel guitar from one key to a different key, the player pushes the lever 30 to the actuated position by pivoting the lever downward which rotates the string puller 26, the pitch adjusters 32, the string supports 34 which moves the tail end of the adjustable strings 20, thereby modifying the length, and thus the tension and pitch, of the adjustable strings 20. When the player desires to return to the open tuning of the steel guitar 10, the player releases the lever 38, and the net biasing force pivots the lever 38 back to the normal position which in turn rotates the string puller 26, the pitch adjusters 32, the string supports 34 and the tail end of the adjustable strings 20 to their unadjusted position for the open tuning of the steel guitar.
Turning now to FIGS. 4-6, a steel guitar 10 having another embodiment of a pitch adjusting device 60 is illustrated. The steel guitar 10 and the pitch adjusting device 60 of the embodiment of FIGS. 4-6 is very similar to the embodiment of FIGS. 1-3 described above, and like reference numerals refer to like elements. Furthermore, the description above for the like elements, features, and operation of the embodiment of FIGS. 1-3 described above shall apply equally to the embodiment of FIGS. 4-6. Thus, only the different elements, features and operations of the embodiment of FIGS. 4-6 will now be described.
The main difference between the pitch adjusting device 60 and the pitch adjusting device 12 is the use of a plate 62 for the string puller 26 instead of the shaft 30. Thus, the pitch adjusting device 60 comprises a string puller 26 which in turn comprises an elongated, substantially flat plate 62. The plate 62 has a pair of pivot members 64, one on each end of the plate 64. The pivot members 64 are tapered surfaces on the forward edge of the plate 62, such as a sharp edge or knife edge to reduce friction and provide a pivot about which the plate 62 can rotate. The pivot members 64 are received in a respective pivot surface 66 in each of the puller mounts 24. Each pivot surface 66 is an arcuate wall surface formed in the respective puller mount 24. The interface of the pivot members 64 and the pivot surfaces 66 define the first axis 27 about which the plate 64 rotates.
The pitch adjusters 32 are attached to the plate 62 by threaded screws which are threaded into a mating threaded hole in the plate 30 of the string puller 26. The centerline of the pitch adjusters 32 is located on first axis 27.
Otherwise, the operation, elements, and features of the embodiment of FIGS. 4-6 is the same as described above for the pitch adjusting device 12 of the embodiment of FIGS. 1-3.
Turning now to FIGS. 7A, 7B and 7C, an alternative embodiment for the plate 64 of the pitch adjustment device 60 and pitch adjusters is shown. The plate 70 includes a main plate 72 which is substantially the same as plate 64 described above. The main plate 72 includes a plurality of string support slots 76 configured to receive and secure the ball end 63 of the adjustable strings 20. A front plate 74 is attached to the front edge of the main plate 72. The front plate 74 forms a gap in which string rollers 76, one for each adjustable string, are located. The front plate also has a string guide slot 78 for each adjustable string 20 in alignment with the respective string 20. The pitch adjusters 80 also have a different design for this embodiment of the plate 70. Instead of a string support 34, each pitch adjuster 80 has a string roller 77 attached to the end of the screw. Adjustment of the pitch adjuster 80 adjusts the radial distance of the string roller 77 from the first axis, thereby adjusting the length, tension and pitch of the adjustable string 20. Otherwise, the plate 70 operates substantially the same as the plate 64, and a pitch adjustment device 60 having the plate 70 operates substantially the with the plate 64.
Referring now to FIGS. 8A and 8B, a string extender 82 is shown which can be used as an accessory for the pitch adjustment devices of FIGS. 1-3 and FIGS. 4-6. For example, in the case that a pitch adjuster 32 is configured to lower the pitch of an adjustable string 20 in the actuated position, the head of the screw is below the string puller 26 and the string support is above the string puller 26. Accordingly, it may be difficult to adjust the pitch adjuster 26 because there is insufficient room to access the head of the screw. The string extender 80 allows provides a device to secure the adjustable string 20 and allow adjustment of the radial distance of the string 20 from the first axis 27 without reversing the orientation of the screw (i.e. the head of the screw is above the string puller 26). The string extender 80 comprises an elongated plate 84 having a ball retainer opening 86 on one end and a hole 88 on the other end. The ball retainer opening 86 has a larger ball hole through which the ball 63 can be inserted and a connecting slot which is narrower such that it does not allow the ball 63 to pass through. The hole 88 is configured to be received on a groove 90 on the screw 92 adjacent the head 94 of the screw 92. The pitch adjuster 32 then comprises the screw 92 and the string extender 80. The pitch adjuster 32 is attached to the string puller 26 by first placing the hole 88 of the string extender 80 onto the groove 90 of the screw 92. The screw 92 is then threaded into the string puller 26 with the head 94 and the string extender 80 above the string puller 26. The ball 63 of an adjustable string 20 is simply inserted the ball retainer opening 86. The string extender 80 can be used on either of the embodiments of pitch adjustment devices 12 and 60.
Turning now to FIG. 9, a steel guitar 10 having another embodiment of a pitch adjusting system 90 is illustrated. The pitch adjusting system 90 comprises two pitch adjustment devices 92 and 94, each of which can be any of the pitch adjusting devices 12 or 60, and can include any of the elements and features, as described above. The first pitch adjusting device 92 and second pitch adjusting device 94 are substantially the same except that the first axis 27 of the first pitch adjusting device 92 is offset from the first axis 27 of the second pitch. Also, the lever 38 of the second pitch adjusting device 94 is located on the top side of the string puller 26 of the second pitch adjusting device 94. The puller mounts 24 of each pitch adjusting device 92 and 94 may be integrally formed as shown in the exemplary embodiment of FIG. 9, or they may each have separate puller mounts 24. Each of the adjustable strings 20 is attached to a pitch adjuster 32 of only one of the pitch adjustment devices 92 or 94. The first pitch adjustment device 92 which is forward of the second pitch adjustment device 94 may have a string guide 96 for guiding an adjustable string 20 past the string puller 26 on the first pitch adjustment device 92 to the string puller 26 on the second pitch adjustment device 94.
The pitch adjusting system 90 is operated in the same manner for each of the pitch adjusting devices 92 and 94, as described above, except that when in use while playing the steel guitar 10, none, either one, or both pitch adjusting devices 92 and 94 can be actuated to achieve a desired tuning of the steel guitar 10.
While embodiments of the present invention have been shown and described, various modifications may be made without departing from the scope of the present invention. The invention, therefore, should not be limited, except to the following claims, and their equivalents.

## Claims

1. An apparatus for selectively adjusting the pitch of the strings of a stringed musical instrument comprising:
a support frame configured to be mounted onto the stringed musical instrument;
a string puller rotatably coupled to the support frame and rotatable about a first axis;
at least two pitch adjusters attached to the string puller at a spaced apart location such that each string pitch adjuster rotates with the rotation of the string puller, each pitch adjuster having a string support for securing a respective adjustable string of the stringed instrument at a respective string position for each pitch adjuster, wherein each pitch adjuster is adjustable to adjust the respective string support to a plurality of different radial positions from the first axis;
a lever coupled to the string puller such that pivoting the lever rotates the string puller relative to the frame about the first axis, the lever having a normal position in which the lever is not being actuated and an actuated position in which the lever is pivoted in a first direction from the normal position.

2. The apparatus of claim 1, further comprising an adjustable actuation stop which limits the pivoting of the lever in the first direction and being adjustable to adjust the actuated position at which the pivoting motion of the lever is limited.

3. The apparatus of claim 1, wherein the adjustable actuation stop comprises a screw threadingly engaged in the lever such that adjusting the screw adjusts the position at which the adjustable actuation stop limits the pivoting of the lever in the first direction.

4. The apparatus of claim 1, further comprising an adjustable open stop which limits the pivoting of the lever in a second direction opposite the first direction and being adjustable to adjust the position of the lever in the normal position.

5. The apparatus of claim 4, wherein the adjustable open stop comprises a screw threadingly engaged in the lever such that adjusting the screw adjusts the position at which the adjustable open stop limits the pivoting of the lever in the second direction.

6. The apparatus of claim 1, wherein the string puller comprises a circular shaft having a circular bearing surface on each end of the shaft which are each received in a respective circular hole in the support frame.

7. The apparatus of claim 6, wherein the at least two pitch adjusters each comprise a screw threadingly attached to a threaded hole in the circular shaft, such that turning the screw adjusts the radial position of the string support.

8. The apparatus of claim 7, wherein each the string support comprises a pin disposed at one end of the screw and configured to secure a ball end of the string.

9. The apparatus of claim 6, further comprising a counterbalancing spring coupled to one of the string puller or the lever and configured to bias the rotation of the string puller against a tension of the strings when secured to the string supports.

10. The apparatus of claim 9, wherein the counterbalancing spring is a tension spring having a first end coupled to the string puller and a second end coupled to the support frame.

11. The apparatus of claim 9, wherein the counterbalancing spring is a compression spring having a first end coupled to the lever and a second end configured to bear against a bearing surface installed on the stringed instrument.

12. The apparatus of claim 1, wherein the string puller comprises a plate having pivot members on each end of the plate which bear against a respective pivot surface on the support frame such that the first axis is defined by the interfaces between the pivot members and the respective pivot surfaces.

13. The apparatus of claim 12, wherein the at least two pitch adjusters each comprise a screw threadingly attached to threaded hole in the circular shaft, such that turning the screw adjusts the radial position of the string support.

14. The apparatus of claim 13, wherein each the string support comprises a pin disposed at one end of the screw and configured to secure a ball end of the string.

15. The apparatus of claim 12, further comprising a counterbalancing spring coupled to one of the string puller or the lever and configured to bias the rotation of the string puller against a tension of the strings when secured to the string supports.

16. The apparatus of claim 15, wherein the counterbalancing spring is a tension spring having a first end coupled to the string puller and a second end coupled to the support frame.

17. The apparatus of claim 15, wherein the counterbalancing spring is a compression spring having a first end coupled to the lever and a second end configured to bear against a bearing surface installed on the stringed instrument.

18. The apparatus of claim 1, further comprising:
a second support frame configured to be mounted onto the stringed musical instrument;
a second string puller rotatably coupled to the second support frame and rotatable about a second axis parallel and spaced apart from the first axis;
at least two pitch adjusters attached to the second string puller at a spaced apart location such that each string pitch adjuster rotates with the rotation of the second string puller, each pitch adjuster having a string support for securing a respective adjustable string of the stringed instrument at a respective string position for each pitch adjuster, wherein each pitch adjuster is adjustable to adjust the respective string support to a plurality of different radial positions from the second axis;
a second lever coupled to the second string puller such that pivoting the second lever rotates the second string puller relative to the second frame about the second axis, the second lever having a normal position in which the second lever is not being actuated and an actuated position in which the second lever is pivoted in a first direction from the normal position.

19. The apparatus of claim 18, wherein:
the string puller comprises a circular shaft having a circular bearing surface on each end of the shaft which are each received in respective circular hole in the support frame; and
the second string puller comprises a circular shaft having a circular bearing surface on each end of the shaft which are each received in a respective circular hole in the second support frame.

20. The apparatus of claim 18, wherein:
the string puller comprises a plate having pivot members on each end of the plate which bear against a respective pivot surface on the support frame such that the first axis is defined by the interfaces between the pivot members and the respective pivot surfaces;
the second string puller comprises a plate having pivot members on each end of the plate which bear against a respective pivot surface on the second support frame such that the second axis is defined by the interfaces between the pivot members and the respective pivot surfaces.

21. The apparatus of claim 18, wherein the support frame and the second support frame are attached to each other or integrally formed with each other.