US3500711A

US3500711A - Vibrato device and stringed instrument incorporating the same

Info

Publication number: US3500711A
Application number: US600615A
Authority: US
Inventors: Clarence L Fender
Original assignee: Columbia Broadcasting System Inc
Current assignee: CBS Broadcasting Inc; Fender Musical Instruments Corp
Priority date: 1966-12-09
Filing date: 1966-12-09
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17

Description

March 17, 1970 c. L. FENDER 3,500,711

VIBRATO DEVICE AND STRINGED IIIS'IRUMIEINT INCORPORATING THE SAME Filed Dec. 9, 1966 3 Sheets-Sheet 1 INVENTOR. cZAPWCE z. Fat/05? March 17, 1970 c. L. FENDER 3,

VIBRATO DEVICE AND STRINGED INSTRUMENT INCORPORATING THE SAME Filed Dec. 9, 1966 3 Sheets-Sheet 2 INVENTOR. CZARENCE L. F'A/DEE March 17, 1970 c. L. FENDER VIBRATO DEVICE AND STRINGED INSTRUMENT INCORPORATING THE SAME Filed Dec. 9, 1966 Sheets-Sheet 5 United States Patent 3,500,711 VIBRATO DEVICE AND STRINGED INSTRUMENT INCORPORATIN G THE SAME Clarence L. Fender, Fullerton, Calif., assignor to Columbia Broadcasting System, Inc., New York, N.Y., a

corporation of New York Filed Dec. 9, 1966, Ser. No. 600,615 Int. Cl. Gd 3/12 US. Cl. 84313 12 Claims ABSTRACT OF THE DISCLOSURE A vibrato device mounted entirely above the face of the guitar includes a tail plate which also acts as the mounting means for the vibrato. A string-engaging element is pivotally mounted on the tail plate by a knifeedge bearing. A leaf spring is used to counteract the pull of the strings on the string-engaging element, and has its forward end secured to the string-engaging element, While its rearward end is engaged by an adjustable stop means capable of varying the neutral position of the string-engaging element.

This invention relates to a vibrator device for stringed instruments, such as hollow-body and solid-body Spanish guitars. The invention also relates to a guitar incorporating such vibrato device.

It is of primary importance, relative to vibrato devices for guitars and similar musical instruments, that the device always return to a precise, predetermined, neutral or zero position upon completion of vibrato action. It is to be understood that the instrument is tuned when the device is at such zero or neutral positions, and that any deviation of the device from the zero position (after the guitarist releases his hand from the device) will cause the instrument to be out of tune. Improper zeroing results from various factors, including friction, and variations in bearing and spring characteristics. It is the belief of applicant that the best zeroing is achieved by providing a knife-edge bearing, the members at the knife edge being hardened, since this produces an absolute minimum of friction and an absolute minimum of deviation of bearing characteristics.

It is, therefore, an object of the present invention to provide a vibrato device, and guitar incorporating the same, which may be constructed to have a knife-edge bearing, with consequent substantially perfect zeroing.

A second important factor relative to vibrato devices is that they should be readily adjustable to vary the zero or neutral position. Such adjustment may be achieved by changing the length of a lever arm, changing the bias of a spring, etc., but in any case adjustability should be readily and simply achieved in order that the zero position and other factors may be varied. One such other factor is the length of the vibrato excursion, on either side of the zero position, which results from a predetermined movement of the vibrato actuating or control arm.

In view of the above, it is a further object of the present invention to provide a vibrato device, and guitar incorporating the same, which is readily adjustable to vary either the spring bias or the length of the lever incorporated in the vibrato, whereby the zero position and/or the excursion from zero resulting from a predeterminated control arm movement may be readily varied.

A further factor which is important in vibrato devices is that the effective inertia thereof be high, whereas the weight of the over-all vibrato should be kept relatively low. When the effective inertia is high, the com- 3,500,711 Patented Mar. 17, 1970 ponents of the vibrato do not tend to vibrate substantially in response to vibration of the string, which vibration of the vibrato tends to damp the string action and thus shorten the dwell time. Stated otherwise, it is desired that nothing in the vibrato device move except in response to an intentional shifting of the device by the hand of the musician.

It is therefore an additional object of the present invention to provide a vibrato device, and guitar incorporating the same, which may be constructed to produce a high inertia] effect, with minimum over-all weight of the device, so that desirable factors including the dwell times of the strings are maximized.

Base and smoothness of operation, and substantial linearity of action, are additional important factors relative to high-quality vibrato devices. It is essential that a device be readily movable by the hand of the guitarist, without exertion of excessive pressure and without substantial undesired pressure variations as the device moves to the various positions normally utilized by a guitarist.

Thus, an additional object of the present invention is to provide a vibrato device, and guitar incorporating the same, which is readily operated and which is relatively linear in its operation throughout a normal operating range.

It should also be emphasized that a high quality commercial vibrato device should be long lasting, simple, compact, relatively economical to manufacture, and desirable in appearance. The various vibrato components must not fatigue or wear to any substantial degree despite many thousands of vibrato movements, and despite the strong tension exerted by the strings.

Many of the above objects have previously been achieved by vibrato devices described in one or more prior patents, namely, Patents Nos. 3,241,418 and 2,972,923. However, at least one very important factor Was not achieved by the constructions shown and described in such patents (as distinguished from constructions comprehended within the claims thereof). Such factor relates to the ability to mount the device on a guitar, and remove the device therefrom, in a very simple manner and without the necessity of providing any portion of the device beneath the face of the guitar. This factor is particularly important relative to hollow-body guitars such as acoustic guitars and acoustic-electric guitars. The ability to mount a vibrato on a guitar in a minimum of time, Without drilling holes in the face of the guitar and without mounting any portion of the vibrato beneath such face, is of extreme importance in hollow-body guitars. It is also required that the vibrato device not be bulky or unsightly.

It is therefore a further important object of the present invention to provide a vibrato device which is mounted above the face of the guitar, such device incorporating a spring means which is low in profile and is characterized by a relatively small excursion so that the device does not appear bulky or unattractive.

Another object not achieved by the constructions shown in the above-cited patents (as distinguished from constructions comprehended Within the claims thereof) is the variation of the pitches of all of the strings by the same proportionate amount, in order that a chord being sounded by the instrument will remain in tune during vibrato operation.

It is therefore an additional object to provide a vibrato device, and guitar, wherein chords being sounded by the strings will (for a given set of strings) remain in tune at all times, including during the vibrato excursions.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a plan view of a guitar incorporating the present invention, most of the neck and some of the head being unshown in order to permit illustration of the body in larger scale;

FIGURE 2 is an enlarged vertical sectional view on line 22 of FIGURE 1;

FIGURE 3 is a further enlarged horizontal sectional view taken generally on line 33 of FIGURE 2;

FIGURE 4 is a transverse sectional view on line 44 of FIGURE 3;

FIGURE 5 is a fragmentary sectional view taken along the broken line 5-5 of FIGURE 3 and showing the vibrato device in a neutral or zero position;

FIGURE 6 is a view corresponding to FIGURE 5 but illustrating the device after downward pressing on the control arm or handle in order to lower the pitches of the strings;

FIGURE 7 is a view corresponding to FIGURES 5 and 6 but illustrating the positions of the parts following elevation of the handle in order to raise the pitches of the strings;

FIGURE 8 is a fragmentary plan view corresponding generally to the left portion of FIGURE 3 but illustrating a second embodiment of the invention wherein roller-type adjustment means are provided in order to vary the zero or neutral position;

FIGURE 9 is a sectional view on line 9--9 of FIGURE 8; and

FIGURE 10 is an enlarged fragmentary vertical sectional view on line 1010 of FIGURE 1.

Referring first to FIGURES 1 and 2 in particular, the invention is illustrated as incorporated in a guitar which has a body 10, neck 11 and head 12, over which are stretched a plurality (illustrated as six) of guitar strings 13. The illustrated guitar is of the acoustic-electric type, having a hollow body and also having an electromagnetic pickup 14 which is suitably associated with an amplifier and loudspeaker, not shown.

Strings 13 are connected at one end to tuning screws 16 on head 12, and at the other end to the vibrato device 17 which forms the present invention. There is interposed between the vibrato device and the tuning screws 16 a bridge 18, which should be of the pivotal or rocking variety as will be described hereinafter. The upper or string-engaging portion of the illustrated bridge 18 may be of the general type illustrated in FIGURES et seq. of US. patent application Ser. No. 439,506, filed Feb. 24, 1965, now Patent No. 3,290,980, for Bridge Constructions for Guitars. The leg portions of the bridge will be described in detail below.

The various elements cooperate to maintain the operative or sound-generating portions of strings 13 in generally a single plane which is parallel to and spaced above the face of the guitar. It is to be understood, however, that the strings may also lie along the surface of an imaginary large-diameter cylinder the axis of which is disposed far below the body and is parallel to the neck. The strings are generally parallel to each other, although they may converge somewhat.

The hollow body 10 is illustrated in FIGURE 2 as having a face 19, back 20 and tail block 21, the latter being associated with the rim, not shown. Formed in face 19 are suitable sound holes, illustrated as F-holes 22. It is emphasized that such F-holes 22 are insufiiciently large to facilitate mounting and demounting the vibrato components in the interior of the body 10. Furthermore, even if the conventional circular sound hole of a classic guitar were present, the mounting of components within the body 10 is distinctly undesirable in a hollow-body guitar for various reasons including undesired variations in the generated sound, difficulty and expense of assembly, inability to remove the vibrato device, and the necessity of providing special internal brace and other elements.

Proceeding next to a detailed description of the vibrato device 17, this comprises a tail plate 24 having two legs 25 which rest upon face 19 in a region relatively adjacent the bridge 18. The tail plate end remote from bridge 18 is hingedly (pivotally) secured to a hooklike mounting bracket 26, the latter being secured to tail block 21 as by the illustrated screw 27 (and/ or other screws) which may also serve as a mounting button for a guitar strap. Thus, the entire vibrato device is readily mounted on the body 10 by one or more screws 27.

As best shown in FIGURE 3, the illustrated tail plate 24 is provided with an opening 28, the edge regions which define such opening preferably converging in a direction toward the mounting hook 26. The outer edges of the tail plate 24 also preferably converge toward the mounting hook.

Means are provided to form a fixed bearing whereby the vibrato-connected ends of strings 13 may be pivotally moved toward and away from head 12, thus varying the string tension and creating the desired vibrato effect. Very desirably, such bearing means is of the above-mentioned knife-edge variety, having exceedingly low friction and being substantially unaffected by long periods of esisting the tensioned strings.

As best shown in FIGURES 37, the knife-edge bearing means illustrated in the drawings comprises crank or lever posts 30 which extend downwardly through oversize openings 31 in tail plate 24. The bottom regions of the posts 30 are annularly grooved at 32 to provide 0pposed frustoconical groove walls. The regions of tail plate 24 surrounding openings 31 are provided with opposed bevels to form frustoconical surfaces which meet at an annular knife edge, a region of such knife edge belng engaged by the apex defined between the groove walls (FIGURES 3-7). Thus, and because the angle between the groove walls is made larger than that between the beveled frustoconical regions defining openings 31, substantially zero-friction pivotal movement is permitted between the position shown in FIGURE 6 and that shown in FIGURE 7.

It is a feature of the illustrated, high-quality vibrato device that the connections between posts 30 and the endS of strings 13 are made through an inertial element 33, the latter being illustrated to comprise a solid metal bar which extends transverse to the strings 13 and generally parallel to the face of the guitar. Thus, the upper ends of posts 30 are shown in FIGURES 4-7 as being threadedly received within interiorly-threaded regions of the inertial bar 33. The upper ends of the threaded bores are open at 34 to permit insertion of a wrench into wrench sockets 35 provided in the upper post ends. Turning of the posts by means of such a wrench varies the distance between inertial bar 33 and the knife-edge bearing, thus changing the lever ratios as described in the above-cited Patent No. 3,241,418.

The string ends are connected to the inertial element 33 in the manner shown in FIGURE 4 of said Patent 3,241,418, and extend beneath such element and over a portion of the bridge 18. It is pointed out that the lower edge regions of the inertial bar 33, which is preferably generally cylindrical in shape as illustrated in the drawings, is sufficiently low that string portions are held down against the upper surfaces of the string-engaging bridge elements.

A vibrato-actuating handle or arm 36 is connected to inertial bar 33 (preferably in the manner shown in FIG- URE 3 of said Patent 3,241,418) in order to effect pivotal movement of the bar 33 about the knife-edge hearing.

There will next be described the very important spring means for opposing the string tension and maintaining the above-indicated elements in a precisely predetermined neutral or zero position at all times except when the indicated control handle 36 is intentionally engaged and operated by the guitarist. Such spring means is illustrated to comprise a leaf spring 38 which extends parallel to, and preferably beneath, the tail plate 24 in a direction away from the head 12 of the instrument. As best shown in FIGURE 3, the leaf spring 38 is generally triangular in shape, in order to achieve a substantial degree of linearity of operation. The opening 28 is shown as being somewhat wider than the spring, to permit upward flexing of the spring into the opening when the device is in oneof its pivoted positions as shown in FIGURE 6.

Means are provided to fixedly connect the wide end of spring 38 to the means which associate the string ends with the bearing. Thus, for example, the wide end of the spring could be connected to the lower ends of posts 30. However, in the illustrated embodiment the wide end of the spring is connected to first and second crank arms 39 (FIGURES 3 and 4) which extend downwardly into opening 28 at locations between the posts 30. The crank arms are illustrated to be formed of screws 40 which extend upwardly through spring 38 into the inertial element 33, a spacer sleeve 41 being provided around each screw and seated between the spring and the under side of the inertial element.

The construction of the leaf spring 38 is important to various factors including ease and linearity of operation, absence of fatigue, and limited vertical excursion in response to pivotal movement of the device between the positionse of FIGURES 6 and 7. It will be understood that it is important to the appearance of the device, and other factors, that the spring neither engage the face 19 of the gutar body, nor exend upwardly an excessive distance, despite the pivoted position to which the vibrato is actuated.

The free position of the spring 38 is shown in FIGURE 7. Referring to such figure, and to the plan view of FIG- URE 3, the spring 38 will be seen to comprise a wide end portion 42 which extends generally perpendicular to the crank arms 39 for a substantial distance toward the tail of the instrument. This wide end of the spring is relatively stiff, the stiffness thereof being further increased by the provision of an additional spring element 43 therebeneath. The second spring 43 is also connected to the crank arms and is generally triangular in shape as shown in FIGURE 3.

The wide, stiff base portion of the spring 38 merges through a slight angle with a long, more flexible truncated triangle 44 (forming the intermediate portion of the spring), Such triangle having edges which converge toward the tail of the instrument. The connection between the wide spring end 42 and the truncated triangle 44 is through a slight angle, as shown in FIGURE 7, it being understood that substantial downward bending of that region of portion 44 which is adjacent portion 42 is prevented by the stiffness of the latter and also by the lower or additional spring 43. The apex of the lower spring 43 lies beneath the central region of portion 44, and is bent slightly upward.

The remaining part of the leaf spring 38 comprises a relatively narrow tongue 46 which is integrally connected with the narrow end of the truncated triangle 44 and eX- tends upwardly therefrom at a substantial angle as shown in FIGURE 7. The tongue 46 preferably forms, as shown in FIGURE 3, an extension of the truncated triangle 44 to thus form a substantially complete triangle thebase of which is associated integrally with spring end 42. The obtuse angle between the tongue 46 and the truncated intermediate portion 44 of the spring, when the spring is in its free position of FIGURE 7, is illustrated as being on the order of about 160 degrees.

Adjustable stop or biasing means are provided above a region of spring 38 remote from the bearing, and preferably above the tongue portion 46 of the spring, to react against the tongue and thus determine (either alone or in conjunction with the adjustable posts 30) the neutral or zero position of the vibrato. In FIGURES 2, 3 and -7 there is illustrated an adjustable stop or biasing means which moves toward and away from the face 19 in order to effect the adjustment. In another embodiment, FIG- URES 8 and 9, the adjustable means moves toward and away from the bearing in order to effect the adjustment.

Regardless of the type of stop or biasing means for the spring region remote from the bearing, clockwise pivotal movement of the inertial element 33 about the knife-edge bearing effects upward flexing of intermediate spring portion 44 (FIGURE 6), the spring then flexing upwardly into the opening 28 in the tail plate. Conversely, counterclockwise pivoting of the inertial element (FIGURE 7) causes the tongue 46 to bear only lightly against, and possibly disengage, the stop therefor. When the device is in the neutral or zero position of FIGURE 5, the intermediate spring portion 44 is slightly flexed as illustrated.

From the above it will thus be understood that the total spring movement or excursion toward and away from face 19 is small, so that the device may have a low profile.

Proceeding next to a detailed description of the adjustable stop or biasing means, first embodiment, this is illustrated to comprise an angle member 47 through which an adjustment screw 48 extends and is threaded downwardly into an interiorly threaded opening in tail plate 24. A second screw 49 in the tail plate has the head thereof seated within a notch 51 (FIGURE 3) between bifurcated ends of the angle member, thus preventing pivotal movement of such member about the first-mentioned screw 48. The ends of element 47 remote from the bearing means engage the plate 24 and provide therewith a fulcrum action.

A depending end portion 52 of the angle member 47 extends downwardly into engagement with the upper surface of a friction-reduction member 53, the latter engaging the upper surface of tongue 46. Member 53 preferably comprises a strip of Teflon (polytetrafluoroethylene). The Teflon strip may be mounted by inserting the screw 48 through a hole therein. Such strip provides a very simple and effective friction-reduction means, and one having characteristics which do not change substantially with time. It is to be understood, however, that it is also within the scope of the invention to provide a roller, for example, at the lower end of member 52, or to coat member 52 with Teflon or the like.

With the described construction, the portion of leaf spring 38 remote from the bearing may be elevated or depressed through an infinite number of positions by merely turning the adjustment screw 48. For this purpose, the head of the screw may be provided with a groove, wrench socket, etc., or may be adapted to be turned manually in the absence of any tool.

Referring next to the embodiment of FIGURES 8 and 9, a roller 54 (or other suitable spring-engaging member) is mounted for shifting longitudinally of the instrument toward and away from the bearing. Roller 54 is shown as mounted on a slide plate 56 having an elongated slot 57 therein through which is extended a screw 58. The screw 58 may be turned, relative to the tail plate 24 into which it is threaded, in order to clamp or release the slide element.

To perform an adjustment operation, it is merely necessary to loosen the screw 58 and slide the plate 56 until roller 54 engages a different longitudinal position along the tongue 46 (or other portion of the leaf spring). Particularly because the tongue 46 is inclined relative to plate 24, such longitudinal shifting of roller 54 changes the zero or neutral position of the vibrato device.

Because of the lever relationships present between roller 54 and inertial bar 33 (or other string-connecting member), the pressure exerted on roller 54 is only a small fraction of the pressure exerted on (for example) the roller bearings for shafts (in prior-art devices) to which strings directly connect.

In summary, therefore, the illustrated vibrato device is in the nature of a bell crank lever having a short arm and a long arm. The short arm extends from the bearing (which is preferably knife-edge) to the string connection element (which is preferably inertial). The long arm is resilient and preferably has associated therewith (remote from the bearing) an adjustable stop. The vibrato control arm is associated with the short arm.

It is pointed out that the posts 30 and crank arms 39 may be replaced by a single element extending from the string connection element to the bearing.

Referring to FIGURE 4, string-receiving grooves 59 are shown as provided in the underside of inertial bar 33 (adjacent the face element 19). Each of such grooves has a bottom wall which is generally a portion of a surface of revolution about an axis coincident with (or adjacent) the axis of the inertial bar. The grooves 59 have different depths, which are correlated to the characteristics of the particular strings 13 for which the vibrato is designed.

Because of the different depths of the grooves 59, the string portions therein are located at different distances from the axis of pivotal movement. Thus, a predetermined increment of pivotal movement will stretch (or relax) the strings by different amounts, which amounts are correlated empirically to maintain the desired tonal relationships between the strings. Therefore, for a given set of strings, the relative pitches remain constant during the vibrato action.

Proceeding next to a description of the rocking bridge 18, this has an upper section 60 which is preferably constructed in the general manner indicated above. Referring to FIGURE 10, legs 61 are threaded upwardly into a casting forming the base of upper section 60, for adjustment by means of a wrench inserted through access holes 62. Thus, the spacing of the upper section 60 above the face 19 may be readily regulated.

The lower ends of legs 61 extend downwardly into oversize sockets 63 formed in foot elements 64 which rest upon face 19. The lower end of each leg is preferably conical, and seats against the apex region of a conical bottom wall of the socket.

To maintain the elements 64 assembled with the legs during initial assembly of the guitar, and to effect centering of the legs during mounting and adjustment of the strings, an O-ring 66 is provided in an annular g oove 67 adjacent the lower end of each leg. The O-ring bears against a cylindrical region of the wall of socket 63.

The described bridge construction permits rocking or pivotal movement of the upper section 60 about an axis parallel to the axis of pivotal movement of inertial element 33, so that there is no substantial friction created by operation of the vibrato device. Furthermore, the described bridge is fully adjustable and is easily assembled.

OPERATION As indicated above, the entire vibrato device is readily mounted on the guitar body 10 by merely inserting one or more screws 27 through the mounting bracket 26 (FIGURE 2), the tail plate 24 then being hingedly connected to such bracket 26 and floating on the face 19 by means of the legs 25. The bridge 18 may be maintained in place by string pressure only, or the feet 44 may be adhesively or otherwise secured to the face 19 if desired.

The illustrated vibrato may be adjusted in either or both of several ways. Thus, for example, the length of the vibrato excursion resulting from actuation of control handle or arm 36 through a predetermined distance may be varied by inserting a wrench through openings 34 (FIGURE and turning the posts 30 to thus change the distance between the inertial element 33 and the bearing. This also changes the pivoted position of the posts 30 because the length of the lever arm is changed, it being pointed out that changing of this lever arm is one way of changing the neutral or zero position (as described in detail in Patent No. 3,241,418, cited above).

The zero or neutral position is also readily changed, as described in detail above, by turning the adjustment screw 48 (FIGURES 5-7) to thus change the elevated position of the lower end of angle portion 52. Also, as described, adjustment of the spring position may be effected by the roller 54 (or equivalent element) in response to longitudinal shifting of the slide plate 56 after screw 58 is loosened, as described relative to FIGURES 8 and 9.

It is emphasized that the neutral or zero position of the vibrato (FIGURE 5) remains fixed at all times unless and until the screw 48 is intentionally adjusted, or the posts 30 intentionally turned. The knife-edge contacts between the posts and the tail plate 24 at openings 31 create almost no friction so that substantially the only friction in the device is that present between the depending end 52 and the spring tongue 46. The latter friction is, however, reduced to a negligible amount by the Teflon element 53. Furthermore, such friction is inherently small because the length of element 44 provides a mechanical advantage which lowers the bearing pressure at portion 52.

The return to a precise zero position (after each release of control handle 36) is to be contrasted with various prior-art devices wherein the bearing friction is high or wherein no true bearings are employed. It is pointed out that even the use of needle bearings, for example, does not eliminate the friction problem because the needles tend to spread (in response to long periods of string tension) and result in a false zero or neutral position.

The linearity of operation of spring 38 is surprisingly great. Such linearity cooperates advantageously with what may be termed the quadrant effect which is present between the string ends and the generally cylindrical undersurfaces of inertial element 33. Referring to FIGURE 5, let it be assumed that it is desired to pivot the element 33 from the illustrated position to that shown in FIGURE 7 (counterclockwise). During the initial portion of such movement, the degree of stretching of the strings 13 (resulting from a predetermined amount of pivoting) will be relatively high. However, as the FIGURE 7 position is approached, a substantially greater amount of pivoting is required to effect a predetermined increment of stretching of the strings 13, this being because the inertial element 33 is then moving largely toward the plate 24 as distinguished from directly away from the head 12 of the instrument. Stated otherwise, the more the control lever or arm 36 is pivoted counterclockwise, as the FIGURE 7 position is approached, the less stretching of the strings 13 is achieved (for a given amount of pivoting). This creates a mechanical advantage which causes the reaction felt by the hand of the guitarist to remain relatively uniform despite considerable stretching of the stroings.

As in the case of the inertial vibrato device described in the above-cited Patent 3,241,418, the inertial effect of element 33 is relatively great (in comparison with the true mass thereof) because the center of mass of element 33 is farther from the knife-edge bearing than are the points of engagement of the strings 13 with the underside of element 33. In other words, the inertial effect is multiplied by the lever relationship. This inertial eifect is important to the highest-quality vibrato action since it minimizes the vibration of the vibrato and thus maximizes the dwell of the strings. It is pointed out, however, that the inertial element 33 may be omitted while still retaining certain important aspects of the present invention.

Guitarists conventionally desire to effect flatting of the strings in response to depression of the handle 36 when the handle is in the position shown in FIGURE 1. This is effected automatically by the lever relationship described herein, and renders unnecessary the provision of extra rollers (with resulting additional friction) such as are required on some vibratos. The additional rollers provided on some prior-art vibrato devices are also undesirable in that additional friction is created due to differential (or varying) stretching of the strings during the vibrato act1on.

As stated heretofore, with particular reference to FIG URE 4, the grooves 59 in element 33 operate to maintain the tuning (of a given class of strings) during vibrato action. Such grooves may, however, be omitted if desired.

The described construction of the leaf spring 38 not only produces relatively linear action, but also minimizes fatigue in that very little bending occurs in a region adjacent the bearing. Thus, the leaf spring is very long lasting and dependable.

The use of the term leaf spring in the present specification and in the appended claims does not necessarily denote that more than one spring is employed (although two or more may be used). Such term is primarily intended to distinguish from torsion springs, helical springs, etc.

The present vibrato device is capable of relatively wide vibrato excusions, yet the leaf spring is so constructed that even such wide excursions do not create excessive fatigue of the spring, or excessive non-linearity of operation.

It is a feature of the present vibrato that the inertial element 33 can be located relatively near the bridge 18. This creates maximum variation in tone in response to a given degree of pivoting. It will be understood that if the vibrato were far from the bridge, much of the string stretching would occur in the inoperative string portions (between the bridge and bar 33).

I claim:

1. A vibrato device for a guitar or similar musical instrument, which comprises:

a mounting element adapted to be mounted over the face of a guitar body,

a string-connecting element adapted to be connected to a plurality of guitar strings,

a bearing to pivotally associate said mounting element and string-connecting element with each other for pivotal movement of said string-connecting element about an axis transverse to said strings,

said bearing being a knife-edge bearing between said string-connecting element and said mounting element,

leaf spring means operatively associated with said string-connecting element to counterbalance the tension of said strings and maintain said string-connecting element in a predetermined desired neutral position, and

means to pivot said string-connecting element about said axis to thus alternately tension and relax said strings and probide a vibrato effect.

2. A vibrato device adapted to be mounted entirely above the fact of a guitar or similar musical instrument, which comprises:

a tail plate adapted to be mounted over the face of a guitar body adjacent the tail thereof,

a string-connecting element mounted on the opposite side of said tail plate from said face,

said string-connecting element being a high-inertia bar extending parallel to said tail plate and spaced thereabove,

a bearing pivotally associating said tail plate with said bar to thereby permit pivotal movement of said bar about an axis parallel to said face and transverse to the strings of the guitar,

said guitar strings extending beneath said bar,

the underside of said bar being rounded about an axis generally parallel to said axis of pivotal movement,

said underside of said bar being spaced a substantial distance farther from said face than is said axis of pivotal movement,

a leaf spring operably associated with said bar and extending generally parallel to said tail plate,

said leaf spring being also operably associated with said tail plate and having such characteristics that said bar is maintained by said leaf spring in a neutral position at all times except when 10 said bar is intentionally pivoted about said axis, and

means to effect pivoting of said bar about said axis to thereby alternately tension and relax said guitar strings and provide a vibrato effect.

3. A vibrato device adapted to be mounted entirely above the face of a guitar or similar musical instrument, 'which comprises:

a bearing pivotally associating said tail plate with said string-connecting element to thereby permit pivotal movement of said string-connecting element about an axis parallel to said face and transverse to the Strings of the guitar,

posts extended downwardly from said string-connecting element to said tail plate,

said posts having annular grooves therein whereby the grooved regions of said posts may engage said tail plate at edges thereof defining openings therein to form said bearing,

said edges having sharp knife-edge regions to thus minimize friction when said posts pivot thereagainst,

a leaf spring operably associated with said string-connecting element and extending generally parallel to said tail plate,

said leaf spring being also operably associated with said tail plate and having such characteristics that said string-connecting element is maintained by said leaf spring in a neutral position at all times except when said string-connecting element is intentionally pivoted about said axis, and

means to effect pivoting of said string-connecting element about said axis to thereby tension and relax the guitar strings and provide a vibrato effect.

4. The invention as claimed in claim 3, in which said posts are threaded into said string-connecting element, and in which means are provided to rotate said posts to thereby vary the distance between said string-connecting element and said knife-edge regions.

5. A vibrato device adapted to be mounted entirely above the face of a guitar or similar musical instrument, which comprises:

said leaf spring being also operably associated with said tail plate and having such characteristics that said string-connecting element is maintained by said leaf spring in a neutral position at all times except when said string-connecting element is intentionally pivoted about said axis, adjustment means provided on said tail plate to bear against a region of said leaf spring remote from said bearing,

said adjustment means being adjustable to determine the neutral position of said spring and of said string-connecting element, and

6. The invention as claimed in claim 5, in which said adjustment means comprises means to effect adjustment of said spring region in directions toward and away from said face.

7. The invention as claimed in claim 5, in which said adjustment means moves in directions toward and away from said bearing, and in which said leaf spring is inclined whereby said adjustment toward and away from said bearing effects adjustment of the initial position of said spring.

8. The invention as claimed in claim 5, in which friction-minimizing material is interposed between said adjustment means and said region of said spring.

9. A vibrato device adapted to be mounted entirely above the face of a guitar or similar musical instrument, which comprises:

a bearing pivotally associating said tail plate with said string-connecting element to thereby permit pivotal movement of said string-connecting element about an axis parallel tosaid face and transverse to the strings of the guitar,

said leaf spring being also operably associated with said tail plate and having such characteristics that said string-connecting element is maintained by said leaf spring in a neutral position at all times except when said string-connecting element is intentionally pivoted about said axis,

said leaf spring being connected to said stringconnecting element by crank means which extends to said string-connecting element independently of said bearing, and

10. A vibrato device, which comprises:

a lever having a short arm,

said lever also having a long arm at least a portion of which is resilient whereby said long arm may be flexed,

means to mount said lever on a guitar body,

said means including a bearing element adapted to permit pivotal movement of said lever about a predetermined axis, said means mounting said lever in such position that said long arm is generally parallel to the face of said guitar body and is above said face, means to connect said short arm to the strings of said guitar and in such manner that the tension of said strings tends to pivot said lever in a predetermined direction about said axis,

stop means associated with said long arm, at a region thereof remote from said axis, to oppose pivotal movement of said long arm in said predetermined direction and responsive to said string tension,

said stop means being unconnected to said long arm, and

manually-operated means to pivot said lever about said axis to thus tension and relax said strings and provide a vibrato effect,

said long arm flexing during said vibrato action and serving upon termination thereof to return said connecting means to a predetermined neutral position.

11. A vibrato device adapted to be mounted entirely above the face of a guitar or similar musical instrument, which comprises:

an elongated tail plate,

means to mount said tail plate generally parallel to and above the face of a guitar body relatively adjacent the tail thereof,

said bearing being interposed between said stringconnecting element and said tail plate whereby the tension of said strings is borne by said bearing,

an elongated flexible spring operably associated with said string-connecting element and extending generally parallel to and beneath said tail plate,

said spring being also operably associated with said tail plate and having such characteristics that said string-connecting element is maintained by said spring in a neutral position at all times except when said string-connecting element is intentionally pivoted about said axis, and

12. A vibrato device adapted to be mounted entirely above the face of a guitar or similar musical instrument, which comprises:

said string-connecting element having a high mass,

said bearing being a knife-edge bearing,

References Cited UNITED STATES PATENTS 1,775,089 9/1930 De Costa 84313 X 3,056,329 10/1962 Butts 84-313 3,124,991 3/1964 Costen 84313 X 3,142,221 7/1964 Boyd 843 13 3,174,381 3/1965 Matthew et al 84313 3,241,418 3/1966 Fender 84-313 3,290,980 12/1966 Fender 843 13 RICHARD B. WILKINSON, Primary Examiner J. F. GONZALES, Assistant Examiner