Abstract:
An improved tremolo mechanism for a guitar. The tremolo mechanism for a guitar includes a rotary assembly. The rotary assembly includes a main rotor that includes an arcuate shaped surface defining holes through which a plurality of guitar strings exit the main rotor when the tremolo mechanism is installed on a guitar, resilient means coupled to said main rotor to bias said rotary assembly to a first position at which no tremolo effect is provided and away from a second position at which a tremolo effect is provided and fixing means on the main rotor for securing one end of each of the plurality of guitar strings to the rotary assembly. The tremolo mechanism also includes a plurality of tension rollers for providing rotational tension to said guitar strings. Said arcuate shaped surface directionally guides said strings transverse of said rotary assembly to the tension rollers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
   This application claims the priority of U.S. Provisional Application Ser. No. 60/761,020, filed Jan. 23, 2006, entitled “TORSION TREMOLO FOR GUITAR”, which is hereby incorporated by reference in its entirety. 

   BACKGROUND 
   1. Field of Invention 
   The present invention relates to improved tremolo assembly for an electric guitar which can replace a standard type tailpiece without modifying the structure of said guitar. 
   2. Description of Prior Art 
   Of most tremolo mechanisms for guitar, there are three types which can replace a standard tailpiece with little or no modification to the body of a guitar. 
   With reference to  FIG. 2 , the first is a stop-tail piece tremolo mechanism consisting of a standard stop-tailpiece with an attached tremolo arm which is assembled to a pivoting bar and a small spring (not shown) which is affixed between the base of the tremolo arm and the stop-tailpiece. The strings are attached to the pivoting bar. When the tremolo arm is pressed down, the distance between the fixing of the strings and the length of the guitar body shortens, producing a mild tremolo effect. A limitation of this type of tremolo mechanism is that the harmony will decrease by only one half-step at most. 
   With reference to  FIG. 3 , the second type of tremolo mechanism, which includes a combined bridge and tailpiece assembly, consists of a tailpiece block which is secured to the body portion of a guitar and an elongated tailpiece member rotatably connected at its ends with the tailpiece block for rotation in one direction about an axis eccentrically, horizontally and vertically offset from the longitudinal axis of the tailpiece member to provide cam action. Adjustable string attachment devices are connected with the tailpiece member for attachment to the ends of the guitar strings which, when tensioned, normally bias the tailpiece member in one direction of rotation. The tailpiece member is spring biased in the other direction of rotation to resist the rotating force exerted on the tailpiece member by the tensioned strings, and at least one lever is connected with the tailpiece member for rotating the same relative to the tailpiece block during sounding of the guitar to produce a tremolo effect. 
   A limitation becomes clear in this as the tailpiece member is pushed down with the attached tremolo arm, which provides a cam action relative to the tailpiece bock during rotation and the front edge (not shown) recedes below the tailpiece block which requires the routing of a space equal in length, width and thickness of said tailpiece member and attached springs (not shown) into the guitar body itself. Altering a guitar body to accommodate improvements in hardware may not be desirable if said guitar were valuable or a vintage collectable guitar. Making these necessary alterations may thus lessen the value of a guitar. 
   Another limitation is that many guitars with a standard style tailpiece vary in distance to the intonation bridge whose purpose is to set the height and most importantly the correct intonation of the strings, which thus makes this type of tremolo unsuitable for many guitars. 
   Yet another limitation of the above mentioned tremolo mechanisms are their use of springs to achieve a tremolo effect. These tremolo mechanisms depend on spring force to return a harmonized chord to its original position after the tremolo arm is pressed and released and are thus subject to variables such as quality, wear and changes in temperature. 
   With reference to  FIG. 4 , a third type of tremolo mechanism provides a tremolo effect for each string according to the variations in string diameter, the rate of elongation of the strings and their materials, and also according to the wishes of the player, to provide a tremolo mechanism that can give a harmonized chord, for instance by temporarily changing the tension in all strings stretched between the headstock and a body of a guitar. A member rotates around a shaft (not shown) when tremolo arm is pressed toward the guitar body. The shaft has its axis positioned transversely to the strings. The shaft is constructed so as to resiliently twist as member rotates. Member is provided with a portion against which the strings press. Portion is positioned between a bridge which supports each of the strings and a fixing part which attaches the end of each string to the front of the guitar body. Fixing part is connected to member and rotates along with it. Fixing part includes means, individual to each string, for changing the distance from the axis of the shaft to the point at which each string contacts portion. Consequently, as member is rotated, it is possible to change the tension in each of the strings. 
   A limitation of this tremolo mechanism is the required removal of both tailpiece, bridge and each respective stud. In addition, four separate holes have to be drilled into the guitar body to affix this tremolo mechanism to the guitar body with screws. Altering a guitar body to accommodate improvements in hardware may not be desirable if said guitar were valuable or a vintage collectable guitar. 
   Another limitation becomes apparent during installation, as the base of the assembly requires a flat surface, while many guitar tops have a contoured or oval surface. 
   SUMMARY 
   An advantage of the embodiments described herein is that they overcome the disadvantages of the prior art. Another advantage of certain embodiments is that they provide an improved tremolo mechanism which can replace a standard tailpiece on a guitar and is capable of providing a tremolo effect for all strings. Another advantage of certain embodiments is that they provide a tremolo mechanism in which the tension of the tremolo arm can be adjusted by a threaded pin. Still another advantage of certain embodiments is that they provide a basic tremolo mechanism that can be used without a spring (which is normally provided in a conventional tremolo mechanism). Yet another advantage of certain embodiments is that they provide a tremolo mechanism which can be adapted to any guitar with a standard tailpiece with out modifying the structure of the guitar. 
   These advantages and others may be achieved by a tremolo mechanism for a guitar that includes a rotary assembly. The rotary assembly includes a main rotor that includes an arcuate shaped surface defining holes through which a plurality of guitar strings exit the main rotor when the tremolo mechanism is installed on a guitar, resilient means coupled to said main rotor to bias said rotary assembly to a first position at which no tremolo effect is provided and away from a second position at which a tremolo effect is provided and fixing means on the main rotor for securing one end of each of the plurality of guitar strings to the rotary assembly. The tremolo mechanism also includes a plurality of tension rollers for providing rotational tension to said guitar strings. Said arcuate shaped surface directionally guides said strings transverse of said rotary assembly to the tension rollers. 
   These advantages and others may also be achieved by a tremolo mechanism for a string instrument that includes a rotary assembly. The rotary assembly includes a main rotor that defines holes through which a plurality of strings exit the main rotor when the tremolo mechanism is installed on a string instrument, a torsion bar coupled to said main rotor to bias said rotary assembly to a first position at which no tremolo effect is provided and away from a second position at which a tremolo effect is provided, and fixing holes defined by rear of the main rotor for securing one end of each of the plurality of strings to the rotary assembly. The tremolo mechanism also includes a plurality of tension rollers for providing rotational tension to said strings. Said main rotor directionally guides said strings transverse of said rotary assembly to the tension rollers. 
   These advantages and others may also be achieved by a guitar capable of producing a tremolo affect that includes a guitar body, a plurality of guitar strings, a plurality of tuning pegs, a guitar bridge, and an improved tremolo mechanism. The tremolo mechanism includes a rotary assembly that includes a main rotor that defines holes through which the plurality of guitar strings exit the main rotor, a torsion bar coupled to said main rotor to bias said rotary assembly to a first position at which no tremolo effect is provided and away from a second position at which a tremolo effect is provided, and fixing holes defined by rear of the main rotor for securing one end of each of the plurality of guitar strings to the rotary assembly. The tremolo mechanism also includes a plurality of tension rollers for providing rotational tension to said guitar strings. Said main rotor directionally guides said guitar strings transverse of said rotary assembly to the tension rollers and said guitar strings are stretched over the guitar bridge and continue along the length of the guitar body to the plurality of tuning pegs. 

   
     DESCRIPTION OF THE DRAWINGS 
     The detailed description will refer to the following drawings, wherein like numerals refer to like elements, and wherein: 
       FIG. 1  is a schematic view of the construction of the whole of an embodiment of an improved tremolo mechanism. 
       FIG. 2  is a side view schematic of a spring loaded stop-tailpiece tremolo mechanism. 
       FIG. 3  is a perspective view of another spring loaded tremolo mechanism. 
       FIG. 4  is a perspective view of a non-spring loaded tremolo mechanism. 
       FIG. 5  is a cross-sectional side elevation view of an embodiment of an improved tremolo mechanism. 
       FIG. 6  is a plan, partially cross-sectional view of an embodiment of an improved tremolo mechanism. 
       FIG. 7  is a perspective view of a rotary shaft of an embodiment of an improved tremolo mechanism. 
       FIG. 8  is a cross-sectional side elevation view of a secondary rotary shaft of an embodiment of an improved tremolo mechanism. 
       FIG. 9  is a schematic elevated front view of a secondary rotary shaft of an embodiment of an improved tremolo mechanism. 
       FIG. 10  is a plan view of a press plate of an embodiment of an improved tremolo mechanism. 
       FIG. 11  is a cross-sectional side elevation view of an embodiment of an improved tremolo mechanism. 
       FIGS. 12A-12C  are various views of an embodiment of a torsion bar of an embodiment of an improved tremolo mechanism. 
       FIG. 13  is a plan view of a guitar body that includes an embodiment of an improved tremolo mechanism. 
   

   DETAILED DESCRIPTION 
   Described herein are embodiments of an improved tremolo mechanism. Embodiments provide an improved tremolo mechanism which can replace a standard tailpiece on a guitar and is capable of providing a tremolo effect for all strings. The embodiments described herein provide, as shown in  FIG. 1 , a tremolo mechanism for a guitar which gives a tremolo effect by temporarily changing the tension in strings stretched between the string fixing and the length of a guitar. 
   With reference now to  FIG. 1 , shown is a perspective view of an embodiment of improved tremolo mechanism or device  100 . Tremolo mechanism  100  includes rotary assembly  10  and press plate/pressboard  20 . Rotary assembly  10  includes a tremolo arm  18  attached thereto. Rotary assembly  10  is placed above press plate  20 , which includes six tension rollers  9  disposed thereon. Tension rollers  9  are fastened to three brackets  8  attached to press plate  20  and below which guitar strings  3  are placed. Guitar strings  3  are inserted into fixing holes  4  (not shown in  FIG. 1 ) in rear of rotational mechanism, exiting through exit holes  4   a  in the front of rotary assembly  10 , following arcuate slope  12  of the front of rotary assembly  10 , and threaded underneath tension rollers  9 . Tremolo mechanism  100  further includes threaded pins  16 ,  17 , which are discussed below. 
   Tremolo mechanism  100  may be fastened to stud screws  1 ,  2  with frame brackets  6 ,  7 . Stud screws  1 ,  2  secure tremolo mechanism  100  to guitar body  5  (not shown in  FIG. 1 ). Existing tailpiece stud screws  1 ,  2  from guitar may be used. 
   With reference now to  FIG. 5 , shown is a cross-sectional view of an embodiment of improved tremolo mechanism  100 . Tremolo mechanism  100  is attached to a guitar body  5  via stud screw  2  and stud screw  1  (not shown in  FIG. 5 ). Guitar string  3  is inserted into a fixing hole  4  in rotary assembly  10 . Guitar string  3  exits out the front of rotary assembly  10  traversing arcuate slope  12  and is threaded under tension roller  9  which is attached to press plate  20  via bracket  8 . Rotary assembly  10  includes torsion bar (or rod)  14  affixed on first end to frame bracket  7  with threaded pin  16 , as shown in  FIG. 5 , and affixed on opposite, second end with threaded pin  17  to rotary assembly  10  (not shown in  FIG. 5 ). Consequently, when downward force is exerted on tremolo arm  18 , rotary assembly  10  rotates in the direction of the arrow. Tremolo arm  18  may be pivoted to a desired position by the guitar player. Tremolo arm  18  can be tightened with threaded pin  21  in order to restrict the pivoting motion so that tremolo arm  18  will remain the desired position. 
   With continuing reference to  FIG. 5 , shown is main rotor  11  of rotary assembly  10 . Rotary assembly  10  also includes main rotor  11 , arcuate slope  12  and cylindrical hollow portion  13  in which torsion bar (or rod)  14  is located. Main rotor  11  is the main body of rotary assembly  10 . Main rotor  11  has cylindrical hollow portion  13  extending transversely to strings  3 . Torsion bar  14  extends coaxially through hollow portion  13  of main rotor  11  between left frame bracket  6  (not shown in  FIG. 5 ) and right frame bracket  7 . As discussed below, one end of torsion bar  14  extends into right frame bracket  7 , to which torsion bar  14  is affixed by threaded pin  16 . Right frame bracket  7  may include a reciprocal cylindrical hollow portion, similar to cylindrical hollow portion  13 , into which torsion bar  14  extends. The other end of torsion bar  14  extends into left frame bracket  6 ; this end of torsion bar  14  is not affixed to left frame bracket  6 , instead being rotatably supported in left frame bracket  6 . Since torsion bar  14  is affixed to right frame bracket  7 , exerting a downward force on tremelo arm  18  rotates main rotor  11 , and remainder of rotary assembly  10 , around torsion bar  14  in direction shown by arrow in  FIG. 5 . 
   With reference now to  FIG. 6  shown is a plan, partial cross-sectional view of an embodiment of improved tremolo mechanism  100 . Shown in this view, tremolo mechanism  100  comprising two frame brackets  6 ,  7  containing rotary assembly  10  and attached to stud screws  1 ,  2  along with a press plate  20 . Guitar string  3  end is inserted into fixing hole  4 , which holds guitar string  3  in place as string  3  exits through exit holes  4   a  over arcuate slope  12  and under tension roller  9 , which is affixed to press plate  20  via bracket  8 . Main rotor  11  is fastened to torsion bar  14  with threaded pin  17 . As discussed above, torsion bar  14  is affixed to right frame bracket  7  with threaded pin  16  while being rotatably supported by left frame bracket  6 . Left frame bracket  6  may also include a cylindrical hollow portion and ball bearings, or other similar known mechanism, for supporting torsion bar  14  and allowing torsion bar  14  to rotate while maintaining its position in left frame bracket  6 . Since main rotor  11  is affixed to torsion bar  14  at one end, main rotor  11  rotates around torsion bar  14  due to torsion bar  14  being affixed to frame bracket  7  when tremelo arm  18  is pressed downward. A torsion effect is created in torsion bar  14  when main rotor  11  rotates as such, biasing main rotor  11  in direction rotational direction (i.e., towards rear of main rotor  11 —where fixing holes  4  located). Tremolo arm  18 , which is inserted into tremolo hole  19 , can be tightened with threaded pin  21  in order to restrict the sideway movement of tremolo arm  18 . 
   Right and left frame brackets  6 ,  7  may be formed as one unit with press plate  20 , and may be mounted onto guitar body  5  (not shown in  FIG. 6 ) with existing tailpiece stud screws  1 ,  2 . 
   With reference now to  FIG. 7 , shown is a perspective view of torsion bar  14  of an embodiment of tremolo mechanism  100 . Torsion bar  14  acts as a rotary shaft of tremolo mechanism  100 , specifically rotary assembly  10 . Torsion bar includes one or more spiral or helical groove  15  that extends from near one end of torsion bar  14  to near the other end. This enables torsion bar  14  to twist but provides opposing force thereto. A torsion effect is achieved when torsion bar  14  is twisted in either direction of its center axis while fixed in place at on end as described above. Main rotor  11  twists with one end of torsion bar  14 , rotating in direction shown in  FIG. 5 , when downward force applied to tremolo arm  18 . 
   With reference now to  FIG. 8 , shown is an elevated front view of a portion of press plate  20  showing two tension rollers  9  connected to bracket  8  via one or more shafts  22  in an embodiment of tremolo mechanism  100 . Tension rollers  9  rotate around shaft(s)  22 . Shaft(s)  22  affix tension rollers  9  to bracket  8  which is fastened to press plate  20  (e.g., via screw). Each tension roller  9  is a tension roller for a guitar string  3  that acts to tighten the tension in guitar string  3  when guitar string  3  is pressed, e.g., by a finger. 
   With reference now to  FIG. 9 , shown is a cross-section side view of a tension roller  9  and bracket  8  on press plate  20  of an embodiment of tremolo mechanism  100 . As noted above, tension roller  9  rotates around shaft  22  and is affixed to bracket  8  which is fastened to the press plate  20 . 
   With reference now to  FIG. 10 , shown is a plan view of press plate  20  of an embodiment of tremolo mechanism  100 . As shown, press plate  20  includes three brackets  8  to which two tension rollers  9  each are attached. 
   With reference now to  FIG. 11 , shown is another cross-sectional side view of an embodiment of improved tremolo mechanism  100 .  FIG. 11  shows tremolo mechanism  100  from the opposite side shown in  FIG. 5 . As described above, tremolo mechanism  100  is attached to a guitar body  5  via stud screw  1  and stud screw  2  (not shown in  FIG. 11 ). Guitar string  3  is inserted into a fixing hole  4  in rotary assembly  10 . Guitar string  3  exits out the front of rotary assembly  10  (via exit hole  4   a ) traversing arcuate slope  12  and is threaded under tension roller  9  which is attached to press plate  20  via bracket  8 . As discussed above, rotary assembly  10  includes torsion bar  14  that is affixed on first end to frame bracket  7  with threaded pin  16  (not shown in  FIG. 11 ) and affixed on opposite, second end with threaded pin  17  to main rotor  11 , as shown in  FIG. 11 . Consequently, when downward force is exerted on tremolo arm  18 , rotary assembly  10  rotates in the direction of the arrow. 
   With reference now to  FIGS. 12A-12C , shown is main rotor  11  of rotary assembly  10 . As discussed above, main rotor  11  has cylindrical hollow portion  13  extending transversely to strings  3 . Torsion bar  14  (not shown in  FIGS. 12A-12C ) extends coaxially through hollow portion  13  of main rotor  11  between left frame bracket  6  and right frame bracket  7  (not shown in  FIGS. 12A-12C ). One end of main rotor  11  is supported rotatably on torsion bar  14 , while the other end is affixed to torsion bar  14  by pin  17 . This allows main rotor  11  (and, hence, rotary assembly  10 ) to freely rotate around torsion bar  14 . 
   With reference now to  FIG. 13 , shown is a plan view of guitar body  5  with an embodiment of tremolo mechanism  100  attached thereto. As shown, tremolo mechanism  100  is installed in place of the standard style tailpiece (not shown). Tremolo mechanism is attached to stud screws  1 , 2  via frame brackets  6 ,  7 . Guitar strings  3  are affixed to tremolo mechanism  100  (e.g., fixing holes in rotary assembly  10 ), are stretched over a standard guitar bridge  30  and continue along the length of guitar body  5  to individual tuning pegs  31 , to which the guitar strings  3  are attached. 
   In operation, tremolo arm  18  can give a tremolo effect while playing the guitar by pressing it down (e.g., by hand). Its clockwise rotation can be tightened by a threaded pin  21  inserted between the lower butt of tremolo arm  18  and the back of main rotary shaft  11 . 
   When tremolo arm  18  is pressed down toward guitar body  5 , main rotor  11  rotates causing torsion bar  14  to twist. When force is removed from tremolo arm  18 , torsion bar  14  will act resiliently to restore tremolo arm  18  (and, hence, rotary assembly  10 ) to its original position. Since torsion bar  14  has grooves cut into its outer circumference, the stresses developed in torsion bar  14  when a rotational force is applied to it are parallel to the direction of the grooves. The stresses are therefore close to the tensile stresses in the same direction, which greatly increases the elastic limit of torsion bar  14 . Accordingly the spring used in a conventional tremolo mechanism is not needed, and the stroke of the tremolo arm is increased, so that when a large stroke is used, the tremolo will always arm return to its original position. 
   When tremolo arm  18  is pressed down, rotary assembly  10  releases the tension in strings  3  without friction due to the rolling action of tension rollers  9  which guide the strings  3  to a standard bridge  30  and along the length of the guitar body  5  to the tuning pegs  31  thereby decreasing the pitch of the strings  3 . When tremolo arm  18  is released, rotary assembly  10  returns the strings  3  to their original tension, thus producing a tremolo effect. 
   While it is intended that the tremolo mechanism be used with a guitar, embodiments may be installed on and used with other string instruments. Furthermore, the guitar may be any type of guitar whether presently conceived of or not. 
   The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention as defined in the following claims, and their equivalents, in which all terms are to be understood in their broadest possible sense unless otherwise indicated.