There is provided a tremolo device for use with a stringed musical instrument wherein the tension in the string is not directly balanced by a spring, but rather a lever riding on a cam surface having a varying curve such that any change in the pull tension on the strings has a minimal effect on the tuning of the instrument.

BACKGROUND OF THE INVENTION 
The present invention relates to a tremolo device for use with a stringed 
musical instrument and more particularly, relates to a new concept in a 
tremolo device. 
Tremolo devices for stringed instruments are widely known and used. They 
are frequently used on electric guitars and are employed to either reduce 
or increase tension on the strings of the musical instrument to produce 
certain desired musical effects. Examples of such tremolo devices may be 
found in, for example, U.S. Pat. No. 4,882,967 to Rose; U.S. Pat. No. 
2,972,923 to Fender; and U.S. Pat. No. 4,555,970 to Rose. 
As described in these patents, a typical tremolo is used with an electric 
guitar which has a body and a neck with a plurality of strings, each 
string being attached adjacent to one end of the neck and extending 
rearwardly to and over a portion of the body of the guitar to the tremolo 
to which it is attached. The strings are attached to a portion of the 
tremolo which is moveable such that the user of the guitar may either 
increase or decrease the tension on the springs to move the tone of the 
guitar in the sharp or flat direction respectively. Typically, prior art 
tremolos utilize a plate or bar to which the strings are attached and 
which plate or bar is pivotable to provide the necessary movement to 
increase/decrease the string tension. In the neutral position, the tremolo 
device usually uses a balancing of forces between string tension and 
springs which are attached to the bar or plate. Thus, when one wants to 
decrease the tension on the strings, one must pivot the plate or bar 
against the spring pressure. In order to increase the tension on the 
strings, one pivots the bar or plate in the other direction against the 
tension on the strings with the spring means being employed to return the 
bar or plate to the neutral position when use of the tremolo is finished. 
Various problems can arise with the use of tremolos and indeed these 
problems are well known in the art and have been addressed in the patent 
literature. Some of the problems include the fact that should one of the 
strings of the guitar break during a performance, the balance existing 
between the total tension of the unbroken strings and the bias of the 
springs is changed and thus the bar or base plate will pivot until the 
tension in the remaining unbroken strings counterbalances the spring bias. 
This naturally results in an instrument which is out of tune. 
Also, on conventional tremolos, the strings are held at approximately the 
same distance from the fulcrum which results in a discordant effect when 
the tremolo is operated with more than one string in play as different 
gauge strings do not descend in pitch directly proportional to the 
distance travelled. 
It is also known that the bias of the springs will change with changes in 
the ambient temperature and thus, a problem is encountered when the 
temperature changes during a performance. Any change in temperature may 
thus require a re-tuning of the instrument. 
Furthermore, when one balances the tension in the strings by spring means, 
there is a certain loss of "punch and edge" in tone compared to fixed 
bridge instruments. This is due to the fact that any change in the tension 
of the string while using the instrument is balanced by spring tension. 
Naturally, there is a certain "give" in the spring and the resultant 
change in the tone of the instrument. 
Still further, use of a technique such as string bending by the fingering 
hand can affect the fine balance between the string tension and the spring 
bias. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a tremolo of a fixed 
bridge type wherein the tension in the strings is not counterbalanced by 
spring bias. 
It is a further object of the present invention to provide a tremolo which 
will not be displaced from its neutral position by string tension changes. 
It is a further object of the present invention to provide a tremolo 
wherein, when the tremolo is utilized, a plurality of strings operate to 
maintain the chord as it ascends or descends in pitch. 
According to one aspect of the present invention, there is provided a 
tremolo device for use with a musical instrument having a plurality of 
strings, the device comprising a housing having a first pivotal member 
which is rotatably mounted. There are means on the first pivotal member 
for receiving and mounting an end of one string thereon such that a 
pivotable movement in a first direction will cause an increase in tension 
on the string and a pivotable movement in a second direction will allow 
for a decrease in tension on the string. The first pivotable member has a 
cam surface associated therewith, the cam surface having a center point 
and an upwardly extending cam surface portion having a decreasing radius 
on one side of the center point and a downwardly extending cam surface 
portion having an increasing radius on a second side of the center point. 
A second pivotable member is mounted on a shaft and is also pivotable with 
respect to the housing and has an arm extending outwardly therefrom which 
is adapted to contact the cam surface and to move therealong. Spring means 
are associated with the second pivotable member. 
In a further aspect of the present invention, there is provided a tremolo 
device for use with a musical instrument having a plurality of strings, 
the device having a housing and a first pivotable member with means 
thereon for mounting one end of the strings. The first pivotable member is 
pivotable in a first direction to increase tension on the strings and 
pivotable in a second direction to decrease tension on the strings. A 
bridge saddle is mounted proximate one end of the housing and the means 
for mounting the one end of the string are in a staggered relationship 
with respect to each other so as to provide a different throw with respect 
to each string when the pivotable member is moved in a pivotable manner. 
In greater detail, the tremolo device according to the present invention 
may be used with an appropriate stringed instrument. The present 
application will describe the use of the invention in conjunction with a 
guitar as this is a widely accepted use of the tremolo although it will be 
understood that other instruments may be utilized. 
The tremolo device, as is conventional, includes a housing or frame member 
which is designed to be attached to the guitar. A conventional means of 
attachment would be by means of screws. 
At one end of the housing there are provided bridge saddles having grooves 
thereon upon which the strings will ride. Means for adjusting the bridge 
saddle may be provided. 
The present invention provides fine tuners which are arranged to receive 
one end of the string. Various arrangements may be utilized including the 
use of an extending pin around which the wire is looped or alternatively, 
a slot to receive a ball at the end of the string could be employed. 
One feature of the present invention is the provision of fine tuners 
wherein the point of attachment thereto for each string is in a staggered 
relationship with respect to the focal point of the fine tuner housing. In 
other words, the distance between the point of attachment of the string 
and the pivot point of the fine tuner housing is varied to allow for 
different throws for each string. Means for adjusting the fine tuners are 
provided. 
The fine tuners are mounted on a first rotatable or pivotable member such 
that a rotatable or pivotable movement in a first direction will cause an 
increase in tension on the string and a pivotable movement in a second 
direction will cause a decrease in tension on the string. 
The first pivotable member has a cam surface associated therewith. This cam 
surface has a center point on one side of which the surface extends in a 
decreasing radius and on the other side of which the surface extends in an 
increasing radius. This cam surface may either be formed integrally as a 
portion of the first pivotable member or alternatively, a separate member 
secured thereto may be employed. 
A second pivotable or rotatable member is also provided and this second 
pivotable member has an arm extending therefrom which is adapted to 
contact the cam surface of the first pivotable member. The arm extends 
from the second pivotable member such that when it contacts the cam 
surface at the center point, it is substantially perpendicular thereto. 
When the second pivotable member is rotated such that the arm moves along 
the cam surface in the direction of the decreasing radius, it will exert a 
force thereon which will in turn translate into a rotatable or pivotable 
movement on the first pivotable member. Similarly, when it moves in a 
direction along the cam surface of an increasing radius, it will permit 
the first pivotable member to move in the opposite direction. 
The second pivotable member has springs means associated therewith to 
assist the return of the arm from the increasing radius to the cam center 
point surface in the direction of increasing radius. Naturally, various 
arrangements of spring members may be utilized. 
The tremolo device, as taught herein, may have several different 
variations. Thus, for example, one could use a plurality of such devices, 
each one being associated with one or more strings. A conventional 
arrangement provides for a single device although, as mentioned, each 
string could have its own individual tremolo. 
Having thus generally described the invention, reference will be made to 
the accompanying drawings illustrating an embodiment thereof, in which:

DETAILED DESCRIPTION OF THE INVENTION 
In greater detail, the tremolo will be described with reference to a guitar 
although other instruments may also incorporate such a tremolo. The 
tremolo includes a frame or housing 10 having a plurality of apertures 12 
by means of which the housing 10 may be attached to the guitar by means of 
suitable screws (not shown). At a front end of housing 10, there are 
provided a plurality of longitudinally extending slots 14 which are 
adapted to receive bridge saddles 16. The device illustrated herein is 
that of a typical guitar and thus, six such bridge saddles 16 are shown. 
Each bridge saddle 16, as may be seen in FIG. 6, comprises a body 18 with a 
groove 20 formed in the upper surface thereof. Groove 20 is of a certain 
size depending on the thickness of the string which it is to receive as is 
well known in the art. Bridge saddles 16 are mounted in slots 14 and are 
longitudinally moveable therein. To this end, there is provided a base 
member 22 for each bridge saddle 18; a pair of threaded members 24 pass 
through body 18 and are screw threadably engageable with a base member 22. 
Thus, tightening of the screws 24 will retain the bridge saddle 16 at the 
desired position within slot 14. 
Connected to housing 10 is a downwardly extending frame member 26. 
Pivotably attached to frame member 26 is a first pivotable member 28 which 
has a base portion 30, a front wall 32 and a back wall 34. As may be seen 
from FIG. 2, first pivotable member 28 is secured to and rotatable with 
respect to frame member 26 by means of a shaft 36. 
Front wall 32 is adapted to receive a plurality of fine tuners 38. Each 
fine tuner 38 comprises a body portion 40 which is pivotably mounted 
between upwardly extending portions of front wall 32 by means of a 
suitable shaft (not shown). Extending rearwardly from body portion 40 is 
an outwardly and rearwardly extending pin 42 as shown in FIG. 2 which is 
adapted to engage and hold one end of musical strings. Extending 
rearwardly from body portion 40 is an integrally formed tab portion 44 
which, as may best be seen from FIG. 5, fits within a slot in back wall 34 
and is moveable upwardly and downwardly. An adjustment screw 46 is screw 
threadably engageable in back wall 34 and extends downwardly into the slot 
to limit the pivotable movement of the fine tuner 38 to thereby provide 
the desired adjustment. 
It will be noted that the heights of each of the fine tuners 38 are 
different or in other words, they are in a staggered relationship. The 
staggered relationship provides the ability to allow for an even pitch 
descent or ascent on the majority of the strings. In other words, in 
conventional tremolos, strings are held at approximately the same distance 
from the fulcrum which does not provide an even chord pitch ascent or 
descent when using the tremolo since the strings, as previously discussed, 
require a different throw for an ascent or descent in pitch. 
At the end of base 30 remote from its pivot point, there is provided a cam 
member 48 having a the upper side thereof. Cam member 48 may either be an 
integral part of base 30 or be a separate member. The surface, has a 
center point 51 (to be discussed hereinbelow); on one side thereof, the 
cam surface 50 has an upwardly extending portion 52 and on the other side 
thereof, has a downwardly extending portion 54. 
A second pivotable member 56 is mounted on a shaft 58 which is journalled 
in housing 10. Second pivotable member 56 has a plate member 60 with an 
arm 62 extending from its center of rotation along shaft 58. Arm 62 has a 
roller 64 mounted on the free end thereof by means of a shaft 66. 
Mounted on shaft 58 are a pair of torsion springs 68 with first ends 70 
thereof being biased against arm 62 and the second end 72 thereof being 
biased against a plate 74 which is secured to the underside of plate 
member 60. Plate 74 contacts the underside of housing 10 to limit the 
movement thereof; on the upper surface of plate 74 there is provided a 
rubber pad 76 as a contact between plate members 60 and 74. 
Extending upwardly from plate member 60 is a lever 78 which is screw 
threadably engageable therewith and functions as the actuater of the 
tremolo. 
The system functions such that when the tremolo is not used and the 
instrument is tuned, arm 62 and roller 64 extend so as to contact cam 
surface 50 at its center point 51. At this point, the forces acting on the 
system are as follows. 
Each strings, attached to a pin 42, passes through groove 20 of bridge 
saddle 16 and thus, exerts an upward force on each fine tuner 38 to 
thereby cause a rotation such that tabs 44 would move upwardly. This 
upward movement is limited by adjustment screw 46 which, as previously 
mentioned, is mounted in back wall 34. Thus the string tension forces are 
transferred to first pivotable member 28 and cam member 48 acts to prevent 
arm 62 from moving to downwardly extending portion 54 of cam surface 50. 
In this respect, it must be understood that the springs 68 do not act 
directly on first pivotable member 28, but rather act to maintain arm 62 
at the center point 51 of cam surface 50. Thus, in normal operation, the 
guitar may be operated in a conventional fashion. 
When it is desired to operate the tremolo device to increase tension on the 
strings, handle 78 is moved such that second pivotable member 56 rotates 
whereby arm 62 will extend onto the upwardly extending portion 52 of cam 
surface 50. Since this is of a decreasing radius, cam member 48 is forced 
downwardly causing pivoting of member 28 about shaft 36 and the downward 
movement of pins 42. 
In order to decrease tension on the strings, handle 78 is moved such that 
arm 62 and roller 64 extends to the downwardly extending portion 54 of cam 
surface 50. This permits the string tension to act to move cam member 48 
upwardly and thereby decrease the tension on the strings. 
As will be seen from the above, there are considerable advantages in the 
arrangement shown. Thus, the strings are not held in a balance with 
springs directly, but rather by means of the action of arm 62 on cam 
surface 50. If one or more strings breaks, this results in a decrease in 
the total force acting on the first pivotable member 28 and would normally 
cause a corresponding movement and loss of tuning. However, since the 
second pivotable member 56 utilizes the springs only to maintain arm 62 in 
the desired position, there is no change or loss of tuning in the strings. 
Similarly, any increase in tension on the springs does not cause movement 
of arm 62 and thus, even during certain actions taken by the guitarist, 
the tuning remains. 
It will be understood that the above described embodiment is for purposes 
of illustration only and that changes and modifications may be made 
thereto without departing from the spirit and scope of the invention.