Patent Publication Number: US-2022223124-A1

Title: Detachable, pitch changing accessory for lap-based stringed instrument

Description:
TECHNICAL FIELD 
     The present disclosure is generally related to musical instruments, and more particularly to an accessory that is configured to be fitted to a stringed instrument to enable adjustment of the pitch of at least one string by altering string tension during play using force applied by the leg of the player. 
     BACKGROUND 
     Stringed musical instruments often include an elongated neck that is attached to a body. Strings are stretched along the neck and at least partly across the body. One end of each string is secured to a tailpiece or saddle mounted to the body and the other end is attached to a tuning machine that is mounted to a headstock at a distal end of the neck. The pitch produced by a string when plucked is determined by the length of the string, string mass per unit length, and tension on the string. The mass per unit length and tension are typically static values corresponding respectively to string selection and a fixed tuning that is set using the tuning machine before the instrument is played. The length of a string is determined by the distance between the bridge and the nut against which the string rests at locations adjacent to the tailpiece or saddle and the headstock, respectively. In order to produce different musical notes, the effective length of selected strings is changed by pressing those strings against the neck at selected locations. For example, a fretboard on the neck may include protruding frets at specific positions corresponding to specific notes. 
     Lap-based stringed instruments such as lap steel guitars, resonator guitars, autoharps, dulcimers, and the like are well known. Lap-based instruments are played while positioned flat across the lap of a sitting player. The strings are typically plucked horizontally by one hand while the other hand moves along the neck and presses strings against the neck to alter the pitch of one or more strings as described above. A pedal steel guitar includes a body mounted to a frame and integral knee levers and foot pedals that adjust the tension of individual strings via push, pull, or push/pull rod linkages. The strings and linkages may extend through the body, which is designed to accommodate the mechanical parts that adjust string tension. The player sits at the instrument with the player&#39;s legs positioned within the frame, under the body, in order to reach the foot pedals and knee levers. 
     SUMMARY 
     In accordance with some implementations, an apparatus comprises: a base configured to be attached to the body of a stringed instrument; and a first leg-actuated lever arm pivotably attached to the base, the first leg-actuated lever arm configured to allow a first string of the stringed instrument to be attached thereto such that pivoting of the leg-actuated lever arm changes tension of the first string. 
     In accordance with some implementations, a pitch adjustment apparatus configured to be attached to a stringed instrument, comprises: a base configured to be attached to the body of the stringed instrument; a first leg-actuated lever arm pivotably attached to the base, the first leg-actuated lever arm configured to allow a first string of the stringed instrument to be attached thereto such that pivoting of the leg-actuated lever arm changes tension of the first string; and a second leg-actuated lever arm pivotably attached to the base, the second leg-actuated lever arm configured to allow a second string of the stringed instrument to be attached thereto such that pivoting of the leg-actuated lever arm changes tension of the second string. 
     In accordance with some implementations, an apparatus comprises: a body; a neck attached to the body; a first string having first and second distal ends, the first distal end of the first string attached to a headstock at a distal end of the neck; and a first leg-actuated lever arm pivotably attached to the body and directly attached to the second distal end of the first string such that pivoting of the first leg-actuated lever arm causes changes of tension of the first string. 
     A variety of other implementations, examples, aspects, and features will be apparent in view of the detailed description and drawings. All examples, aspects, and features mentioned in this document can be combined in any technically possible way. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a front perspective view of an accessory that is configured to be fitted to a stringed instrument to enable adjustment of the pitch of at least one string during play by altering string tension using part of the player&#39;s leg. 
         FIG. 2  is a back perspective view of the accessory of  FIG. 1 . 
         FIG. 3  is a top plan view of the accessory of  FIG. 1 . 
         FIG. 4  is a bottom plan view of the accessory of  FIG. 1 . 
         FIG. 5  is a side view of the accessory of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 5  illustrate an implementation of an accessory that is configured to be fitted to a stringed instrument to enable adjustment of the pitch of at least one string during play by altering string tension using part of the player&#39;s leg. The illustrated accessory includes a base plate  10  and two lever arms  12 ,  14  that enable independent adjustments of the pitches of two strings  26 ,  64 . The first lever arm  12  is calf-actuated, and the second lever arm  14  is thigh actuated, although the parts of the player&#39;s body used to move the lever arms should not be viewed as a limitation. The base plate  10  is configured to be attached to the underside (back) of the body  16  of a wide variety of stringed instruments, e.g., as a retrofitted accessory that can be installed and removed as desired. The base plate may be secured to the back of a standard solid body guitar or other stringed instrument with fasteners  18  such as machine screws or wood screws that extend through mounting holes formed through the base plate and into corresponding mounting holes drilled into the body of the instrument. Threaded inserts may be inserted into the holes formed in the body of the instrument to enable use of machine mounting screws. The base plate  10  is secured to the body  16  in a position such that a portion of the base plate extends away from the body at a distal end of the instrument and is in lengthwise alignment with the neck and strings. As will be explained below, this enables the strings to be attached to the accessory without being routed through holes in the body of the instrument. 
     The calf-actuated lever arm  12  extends through an opening formed in the base plate  10  and is positioned such that a first distal end is located below the bottom of the (horizontally-positioned) body  16  of the instrument and a second distal end extends upward beyond the top of the body of the instrument. The calf-actuated lever arm pivots around a shoulder screw  20  that is inserted into a bearing  22  that is press-fitted into a hole in the lever arm  12 . The shoulder screw extends through the bearing between two lever pivot mounts  24 . The calf-actuated lever arm  12  is positioned laterally in alignment with a selected one of the strings  26  by selective positioning of the base plate  10  relative to the body  16  of the instrument and use of bearing spacers mounted to the shoulder screw between the calf-actuated lever arm and both the string guide and adjacent thigh-actuated lever arm. The string  26  to be tension-controlled is fed through a string guide hole  28  formed through a first distal end of the lever arm and secured to the calf-actuated lever arm. A lever extension  30  is attached to a second distal end of the calf-actuated lever arm. A fixed calf plate  32  is attached to the lever extension at a distal end opposite to the lever arm attachment bearing. The calf plate provides an ergonomic point of contact via which the player can comfortably move the calf-actuated lever arm in a controlled manner by application of force via the player&#39;s calf. 
     The lever extension  30  may be foldable. The lever extension pivots and can be temporarily fixed at a variety of rotational positions at the point of attachment with the lever arm by a cam latch  34 . Thus, the lever extension  30  can be secured at a desired rotational position relative to the calf-actuated lever arm  12  when the instrument is being played and secured in a stowed rotational position in order to enable the instrument to be more easily stored and transported. 
     The calf-actuated lever arm  12  is held in a default, maximum string tension position by a tension spring  38 . The tension spring is attached to the calf-actuated lever arm at a first end and to a spring tension block  40  at a second end. For example, the tension spring may be stretched between a first spring attachment screw  42  that is attached to the calf-actuated lever arm and a second spring attachment screw  44  that is attached to the spring tension block  40 . Maximum spring tension is adjusted by altering the distance between the spring tension block  40  and the calf-actuated lever arm  12  using a spring tensioning screw  78  that extends through a tension screw mount block  48  into a threaded hole in the spring tension block  40 . The tension screw mount block  48  is fixedly (statically) attached to the base plate  10 . Unthreaded openings in an extension  50  of spring tension screw guide  52  keeps the spring tensioning screw, and thus the spring tension block, in alignment with the calf-actuated lever arm. A fixed lever stop  90   a  sets a first limit of rotational travel of the calf-actuated lever arm  12  relative to the base plate  10 , i.e., the default, maximum string tension position at which the calf-actuated lever arm is positioned when not actuated. An adjustable tuning stop  54  sets a second limit of rotational travel of the calf-actuated lever arm relative to the base plate, thereby defining the tension change and pitch change of the string that is achieved when the calf-actuated lever arm is fully actuated by the player, e.g., to the minimum string tension. The adjustable tuning stop  54  may be set such that the difference between the maximum and minimum string tension corresponds to a half or whole step change in pitch, for example, and without limitation. The adjustable tuning stop may be formed at a first distal end of a threaded tuning key that traverses a corresponding threaded hole formed in a tuning block that is mounted to the base block. A knurled knob  56  or other feature may be formed at a second distal end of the tuning key to facilitate tool-less setting of the calf-actuated lever string tuning by setting the second limit of rotational travel. 
     The thigh-actuated lever arm  14  extends through the opening in the base plate  10  adjacent to the calf-actuated lever arm and is positioned such that a first distal end is below the (horizontally-positioned) body  16  of the instrument and a second distal end extends beyond the top of the body of the instrument. The thigh-actuated lever arm pivots relative to the base plate at a shoulder screw  60  that rotates within a bearing  62  that is press-fitted into a hole in the thigh-actuated lever arm. The shoulder screw extends through the bearing between the two lever pivot mounts. The thigh-actuated lever arm is positioned laterally in alignment with a selected one of the strings  64  by selective positioning of the base plate and use of bearing spacers mounted to the shoulder screw between the thigh-actuated lever arm and both the string guide and adjacent calf-actuated lever arm. The string  64  is fed through a string guide hole  66  formed through a first distal end of the thigh-actuated lever arm and secured to the thigh-actuated lever arm. 
     A linkage between a thigh plate  68  and the thigh-actuated lever arm  14  is formed by first and second elongated members  70 ,  72 . The first elongated member  70  is fixedly attached to the thigh plate  68  at a first distal end and pivotably attached to the base plate  10  at a second distal end, e.g., via a bearing formed by a hole and pivot screw. The second elongated member  72  is pivotably attached to the thigh-actuated lever arm  14  at a first distal end and pivotably attached to the first elongated member  70  at a second distal end. More specifically, the second elongated member is pivotably attached to the first elongated member at a location on the first elongated member between the first and second distal ends thereof. A pivot screw and pivot spacer may be used to pivotably attach the second elongated member to the thigh-actuated lever arm. Force applied against the thigh plate  68  by the player causes the first elongated member  70  to rotate relative to the base plate  10 , which in turn causes the second elongated member  72  to transfer force from the rotating first elongated member to the thigh-actuated lever arm  14 , thereby rotating the thigh-actuated lever arm and changing the pitch of the string by changing the tension thereof. 
     A tensioning spring  74  is attached to the thigh-actuated lever arm  14  at a first end and to a spring tension block  76  at a second end, e.g., stretched between a first spring attachment screw that is attached to the thigh-actuated lever arm and a second spring attachment screw that is attached to the spring tension block. The spring tension is adjusted by altering the distance between the spring tension block  76  and the thigh-actuated lever arm  14  using a spring tension adjustment screw  78  that extends through a tension screw mount block into a threaded hole in the spring tension block  48 . The tension screw mount block is fixedly attached to the base plate. Unthreaded openings in extension  50  of the unthreaded spring tension screw guide  52  keeps the spring tension screw, and thus the spring tension block, in alignment with the thigh-actuated lever arm. A fixed lever stop  90   b  sets a first limit of rotational travel of the thigh-actuated lever arm relative to the base plate at which the thigh-actuated lever arm is positioned when not actuated. An adjustable tuning stop  82  sets a second limit of rotational travel of the thigh-actuated lever arm relative to the base plate, thereby defining the tension change and pitch change of the string when the thigh-actuated lever is fully actuated. The adjustable tuning stop may be set such that the tension of the string decreases by an amount corresponding to a half or whole step change in pitch. The adjustable tuning stop may be formed at a first distal end of a threaded tuning key that traverses a corresponding threaded hole formed in a tuning block that is mounted to the base block. A knurled knob  84  or other feature may be formed at a second distal end of the tuning key to facilitate tool-less setting of the thigh-actuated lever string tuning. 
     While not considered to be a limitation of the invention, the illustrated accessory is suitable to be retrofitted to a variety of solid body guitars to provide a lap steel instrument with one or more leg-actuated string pitch adjustment features. The instrument can be set to a standard tuning, e.g., an open chord, using the tuning machines of the instrument. The selected strings, e.g., third and fourth strings, are attached to the respective lever arms and the adjustable tuning stops set to lower spring tension by an amount corresponding to a half or whole step when the respective lever is actuated. This can allow the player to produce, for example, the major chord, 7th, minor, and minor 7th by manipulating the calf and thigh plates while playing. The positive stops enable accurate, hands-free pitch changes. 
     Although each lever arm has been described as allowing attachment and tension adjustment of a single string, a single lever arm could be attached to multiple strings to provide coordinated tension adjustment. Furthermore, a mechanism to connect two lever arms together temporarily and reversibly could be used to provide coordinated tension adjustment of two or more strings. For example, if the player planned to perform a piece of music that required only the minor 7 th  leg-actuated adjustment then a linking pin or other feature could be used to secure the lever arms to each other such that both strings would be tension-adjusted by application of force via the player&#39;s thigh or calf. 
     Although an accessory configured to be attached to an instrument has been described, the concepts disclosed herein could be integrated into an instrument. For example, the lever arms could be routed through the body of the instrument and be directly, pivotably attached to the instrument. Moreover, the inventive concepts are not limited to an instrument that is played while positioned on the lap of the player. 
     A number of features, aspects, embodiments, and implementations have been described. Nevertheless, it will be understood that a wide variety of modifications and combinations may be made without departing from the scope of the inventive concepts described herein. Accordingly, those modifications and combinations are within the scope of the following claims.