Abstract:
This is an improved latch for a collapsible stringed musical instrument providing for a two step assembly or disassembly and combining all operations into a single lever, knob, or cam. A snap action catch holds the instrument in the intermediate position, resisting the stings tension, allowing for a second step to tighten or loosen the neck to the body of the instrument without de-tuning the instrument&#39;s strings.

Description:
FIELD OF INVENTION 
     This invention relates to collapsible stringed musical instruments 
     BACKGROUND 
     Prior Art 
     The following is a tabulation of some prior art that presently appears relevant: 
     
       
         
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 U.S. Patents 
               
             
          
           
               
                   
                 Pat. No. 
                 Kind Code 
                 Issue Date  
                 Patentee 
               
               
                   
                   
               
               
                   
                 5,353,672 
                   
                 Oct. 11, 1994 
                 Stewart 
               
               
                   
                 6,028,255 
                   
                 Feb. 22, 2000 
                 Myronyc 
               
               
                   
                 7,375,267  
                 B2 
                 May 20, 2008 
                 Poschelk 
               
               
                   
                   
               
             
          
         
       
     
     A conventional stringed musical instrument is normally an assembly of a neck and body in one piece. Many of the instruments are too large for convenient travel as hand luggage on airplanes, and must be checked with the airline and transported in the baggage hold of the airplane, subjecting the instruments to damage from rough handling and crushing. In order to allow carrying onboard as hand luggage, some of these instruments have a neck to body joint that allows folding and or separation of the two parts, thus reducing the length of the instrument to an acceptable size. 
     It is also helpful to be able to fold or separate the neck from the body without reducing the tension in the strings. This greatly reduces the time and effort required to re-tune the instrument after assembly, as well as reducing the time required for disassembly. 
     But, the instrument is relatively large and delicate, requiring care in handling while assembling and disassembling. Force is required to hold the neck to body joint in place against the tension force in the strings while simultaneously tightening or loosening the fixings. Also, moving the neck against the tension in the strings requires a different grip than tightening or loosening its connection to the body. 
     Therefore, it is advantageous to have a latch that holds the guitar assembly in an intermediate position in order to allow for the user to re-grip the instrument and complete the assembly or disassembly. 
     For assembly, it is easier if the latch has a snap action feature that automatically engages and holds the two parts of the instrument in an intermediate position. This feature allows the neck to be pushed into the intermediate position and held there by the latch until the tightening procedure can be accomplished. 
     For disassembly, it is easier if the latch releases is in 2 steps. The first step allows the neck to separate from the body to an intermediate position, releasing some spring tension, and the latch holding the neck in this position until the latch is completely released. 
     Finally, it is easier and more efficient if the latch is operated by manipulating only one element of the latch. 
     Several types of quick disconnect necks have been proposed. One has no means for intermediate position latching, requiring the user to hold the neck in place against the tension of the strings while simultaneously latching the neck in place. 
     U.S. Pat. No. 7,373,267 B2 to Poschelk (2008) proposes such a latch, using a cam lever system mounted to the bottom of the body of the instrument. 
     Two other proposals have the preferred intermediate position for latching, although neither one proposes a single lever for latch operation. 
     U.S. Pat. No. 535,672 to Stewart (1994) proposes various snap action latches with separate tightening screws. One embodiment ( FIG. 9 ) proposed a snap action latch combined with a tightening screw, but this embodiment offers no means of releasing the latch for disassembly. 
     U.S. Pat. No. 6,028,255 to Myronyk (2000) proposes two latch systems that uses a cam lever for final tightening. One proposal uses a separate knob is used to load the latch arm to engage or disengage. The second proposal uses a system similar to a ball point pin whereby alternating pushes of the cam lever will load the latch springs to engage or disengage. 
     ADVANTAGES 
     Accordingly several advantages of one or more aspects my invention are a latch assembly, operated by a single lever, cam, or screw that provides for:
         (a) assembly and disassembly of the body to neck joint without de-tuning or slacking string tension, and   (b) provides an intermediate snap action latching position against the tension force of the strings, and   (c) provides an integral one step release from this intermediate position, and   (d) provides an integral tightening mechanism to hold the joint in its assembled position, and   (e) does not adversely affect the musical tone and vibration characteristics of the instrument.   Other advantages of one or more aspects will be apparent from a consideration of the drawings and ensuing description.       

     DRAWINGS 
     Reference Numerals—all Embodiments Shown 
     
         
         
           
               1  Neck 
               2  Latch Arm 
               3  Latch Arm Pivot 
               4  Thrust Washer 
               5  Thumb Screw 
               6  Body 
               7  Neck Extension 
               8  Strings 
               9  Cam Lever 
               10  Catch Pin 
               11  Latch Housing 
               12  Spring  1   
               13  Snap Ring 
               14  Spring Shoe 
               15  Cam Screw 
               16  Spring  2   
           
         
       
    
    
    
     
       DRAWINGS 
       Figures 1 St  Embodiment 
         FIG. 1  is a top view of a guitar, 
         FIG. 1A  is a partial section view of the neck to body joint in the assembled position, 
         FIG. 1B  is a partial section view of the neck to body joint in the intermediate position, 
         FIG. 1C  is a partial section view of the neck to body joint in the initial released position, 
         FIG. 1D  is a partial section view of the neck to body joint in the assembled position (spring  16  not shown), 
         FIG. 1E  is a partial section view of the neck to body joint in the intermediate position (spring  16  not shown), 
         FIG. 1F  is a partial section view of the neck to body joint in the initial released position, 
         FIG. 2  is an exploded view of the latch components only, 
         FIG. 3  is a view of the latch components only and their relative movements, 
         FIG. 4  shows a neck to body joint in the assembled and hinged positions 
     
    
    
     DETAILED DESCRIPTION 
     1 St  Embodiment 
     One embodiment of the latch is illustrated in  FIG. 1  (top view),  FIG. 1A  (partial section assembled position),  FIG. 1B  (partial section assembled position), and  FIG. 1C  (partial section released position).  FIG. 3  shows the latch components isolated from the body and neck. A latch housing  11  is glued or fixed to a neck  1  and provides a guide channel for the latch arm  2  and a latch pivot pin  9  to translate and pivot as shown. A catch pin  10  is fixed to a body  6  and a spring  12  provides a restoring force to engage the latch arm  2  with the catch pin  10 . A thrust washer  4  is fixed to the neck  1  and provides a surface for a thumb screw  5  to bear on and pull the neck  1  tightly to the body  6  via its threaded connection to the latch arm  2  and also a surface for a snap ring  13  to bear on. The snap ring  13  is mounted on a groove in the thumb screw  5 . The thrust washer  4  has a slotted hole to allow the thumb screw  5  to move up and down, thus moving the latch arm  2  relative to the catch pin  10 .  FIG. 4  shows the neck  1  hinging around its abutment to a neck extension  7  and thus completely releasing all the strings  8  tension. 
     OPERATION 
     Starting with the assembled instrument, loosen the thumb screw  5  until the snap ring  13  bears on the thrust washer  4  allowing the neck  1  to hinge about its abutment with the neck extension  7  thus slightly releasing the strings  8  tension. The latch will hold the instrument in this partially disassembled position. The entire instrument can be re-positioned to push down on the neck to slightly relieve the force on the latch arm  2  to the catch pin  10  connection. Push up on the thumb screw  5  to rotate and release the latch arm  2  from the catch pin  10 , then release the downward pressure on the neck  1  to complete disassembly of the joint. Assembly requires pushing down on the neck  1  to engage the latch arm  2  with the catch pin  10 . The latch will hold the instrument in this partially assembled position, allowing the user to re-position the entire instrument and tighten the thumb screw  5  to bring the neck  1  to body  6  joint to the assembled position. 
     ALTERNATIVE EMBODIMENT 
     DETAILED DESCRIPTION—ALTERNATIVE EMBODIMENT 
     Another embodiment of the latch is illustrated in  FIG. 1  (top view),  FIG. 1D  (partial section assembled position),  FIG. 1E  (partial section intermediate position),  FIG. 1F  (partial section initial released position), and  FIG. 2  an exploded view showing the latch components isolated from the body and neck. The latch housing  11  is glued or fixed to the neck  1  and provides a guide channel for the latch arm  2  and latch pivot pin  3  to translate and pivot. The catch pin  10  is fixed to the body and the spring  12  provides the restoring force to engage the latch arm  2  with the catch pin  10 . The thrust washer  4  is fixed to the neck  1  and provides a surface for the cam lever  3  to bear on and also a surface for a spring  13  to bear on. Spring  13  provides the restoring force to keep the latch arm  2  extended toward the catch pin  10 . A cam lever  9  pulls the neck tightly to the body  6  via its pinned connection to a cam screw  15  and the cam screw  15  threaded connection to the latch arm  2 . The cam screw  15  threaded connection to the cam lever  9  provides a method for tension adjustment. The thrust washer  4  has a slotted hole to allow the cam lever  9  and cam screw  15  to move up and down, thus moving the latch arm  2  relative to the catch pin  10 , releasing the neck  1  and allowing the neck  1  to hinge around its abutment to the neck extension  7  and thus completely releasing all the strings  8  tension. 
     OPERATION OF ALTERNATIVE EMBODIMENT 
     Starting with the assembled instrument, rotate the cam lever  9  until the cam lever shoulder bears on the cam screw  15  allowing the neck  1  to hinge about its abutment with the neck extension  7  thus slightly releasing the strings  8  tension. The latch will hold the instrument in this partially disassembled position. The entire instrument can be re-positioned to push down on the neck  1  to slightly relieve the force on the latch arm  2  to catch pin  10  connection. Push up on the cam lever  9  to rotate and release the latch arm  2  from the catch pin  10 , then release the downward pressure on the neck  1  to complete disassembly of the joint. Assembly requires pushing down on the neck  1  to engage the latch arm  2  with the catch pin  10 . The latch will hold the instrument in this partially assembled position, allowing the user to re-position the entire instrument and rotate the cam lever  9  to bring the neck  1  to body  6  joint to the assembled position. 
     ADVANTAGES 
     From the description above, a number of advantages of some embodiments of my invention become evident:
         (a) The latch provides a 2 step process for assembly or disassembly of the instrument thus making it easier for the user to control the forces coming from the string tension.   (b) The latch consists of a cam, lever, or screw that tightens or loosens the connection between the separate parts of the instrument, thus moving the parts between the assembled position and the intermediate position   (c) On assembly, the separate parts of the instrument are pushed together causing the latch to snap and hold the parts in partially assembled position, allowing the user to re-grip the instrument for final assembly.   (d) On disassembly, the latch is released allowing the separate parts of the instrument to move away from each other, slightly releasing string tension, and allowing the user to re-grip the instrument for final disassembly.   (e) The latch is a compact assembly requiring the user to manipulate only one latch element for all operations.   (f) The instrument can be assembled and disassembled without slacking or de-tuning the strings reducing the time and effort required to perform those operations   (g) Any stringed instrument with a neck can be reduced in size so as to make it more convenient for travel.   (h) The latch does not require large modifications to the normal construction and characteristics of an industry standard stringed instrument.       

     CONCLUSIONS, RAMIFICATIONS, AND SCOPE 
     Accordingly, the reader will see that at least one embodiment of my latch provides an easier to use collapsible stringed musical instrument. Also, my latch will not alter the basic industry standard shape for stringed musical instruments. My latch can be used on, but not limited to, solid body guitars, hollow body guitars, banjos, mandolins, violins, and ukuleles. My latch makes travel with a collapsible stringed musical instrument a more practical alternative than travel with non-collapsible stringed musical instruments. 
     While my latch has been described and defined by reference to the embodiments shown, such reference does not imply a limitation on the scope of the embodiments, and no such limitation is to be inferred. My latch is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled and knowledgeable in the pertinent arts. The depicted and described embodiments of my latch are exemplary only, and is not exhaustive of the scope my invention. Consequently, the scope is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.