GB2562791A

GB2562791A - Vibrato assembly for a stringed instrument

Info

Publication number: GB2562791A
Application number: GB1708463.3A
Authority: GB
Inventors: Lewis Jeremy
Original assignee: Jeremy J Lewis Guitars Ltd
Current assignee: Jeremy J Lewis Guitars Ltd
Priority date: 2017-05-26
Filing date: 2017-05-26
Publication date: 2018-11-28
Anticipated expiration: 2037-05-26
Also published as: GB201708463D0; GB2562791B

Abstract

A vibrato, tremolo or whammy bar assembly 100 for a stringed instrument such as a guitar, comprises a chassis 102 for rigid attachment to a body of the instrument, a moveable bridge support 104 to which one or more strings of the instrument are anchorable, and first and second spring plate elements 106, 108 for holding the bridge support substantially parallel to the chassis. There is at least one balancing spring for coupling the bridge support to the chassis to bias the bridge support against the tension of the strings in use, and an actuator lever 168 coupled to the chassis and the bridge support and operable to displace the bridge support with respect to the chassis in a substantially linear motion from a neutral position (figure 8(b)) to change the pitch of the strings (see figures 8(a) and 8(b)). In embodiments the chassis, bridge plate and spring plates form a box with a substantially parallelogram shaped cross-section to maximise acoustic transfer from the strings to the body of the instrument and reduce movement of strings away from the instrument body.

Description

(54) Title of the Invention: Vibrato assembly for a stringed instrument

Abstract Title: Vibrato assembly enabling substantially linear movement of the bridge support (57) A vibrato, tremolo or whammy bar assembly 100 for a stringed instrument such as a guitar, comprises a chassis 102 for rigid attachment to a body of the instrument, a moveable bridge support 104 to which one or more strings of the instrument are anchorable, and first and second spring plate elements 106, 108 for holding the bridge support substantially parallel to the chassis. There is at least one balancing spring for coupling the bridge support to the chassis to bias the bridge support against the tension of the strings in use, and an actuator lever 168 coupled to the chassis and the bridge support and operable to displace the bridge support with respect to the chassis in a substantially linear motion from a neutral position (figure 8(b)) to change the pitch of the strings (see figures 8(a) and 8(b)). In embodiments the chassis, bridge plate and spring plates form a box with a substantially parallelogram shaped cross-section to maximise acoustic transfer from the strings to the body of the instrument and reduce movement of strings away from the instrument body.

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-1 VIBRATO ASSEMBLY FOR A STRINGED INSTRUMENT

FIELD OF THE INVENTION

The present invention relates to vibrato assemblies for stringed musical instruments. In particular, but not exclusively, the invention relates to vibrato assemblies for producing pitch-change effects in a guitar.

BACKGROUND TO THE INVENTION

Many stringed instruments, and in particular electric guitars, include a mechanical arrangement for varying the tension of the strings by means of a control arm or bar that can be operated by the player’s picking or strumming hand. In the field of electric guitars, the control arm is commonly known as a “tremolo arm” or “whammy bar”, although the musical effects created by such a device can be more properly described as vibrato (a rapid fluctuation in pitch) and portamento (pitch rises or dives).

The most common versions of such arrangements use a rocking fulcrum principle, as shown in Figures 1 and 2. Each string 10 is anchored to a moveable or floating bridge plate 12 by a tail piece 14 that is mounted on the bridge plate 12. The bridge plate 12 is mounted to the instrument body 16 at a pivot 18 disposed at the front or head side of the bridge plate 12, closest to the neck of the guitar. The tension of the strings 10 is counterbalanced by springs mounted in the body of the guitar (not shown in Figures 1 and 2), so that the bridge plate 12 rests in a neutral position when the strings 10 are in normal tune.

A control arm 20 is affixed to the bridge plate 12. Movement of the control arm 20 towards or away from the body 16 of the guitar causes the bridge plate 12 to turn about the pivot 18, resulting in a decrease or increase in string tension respectively and a corresponding decrease or increase in pitch when the strings 10 are played.

-2The pivot 18 may comprise a roller or ball bearing arrangement 22, as illustrated in Figure 1, a knife-edge hinge arrangement 24 as shown in Figure 2, or one of various alternative designs. Examples of such rocking fulcrum vibrato arrangements are described in US Patent Nos. 2,741,146, 4,171,661 and 5,986,191.

One well-known characteristic of rocking fulcrum arrangements is that the rotation of the bridge plate causes the strings to move away from or move closer to the neck of the guitar as the pitch is raised or lowered, respectively.

Alternative arrangements that seek to avoid this characteristic have been developed. In these arrangements, the bridge plate is arranged for linear movement, parallel to the body, so that the tension of the strings is adjusted without a change in the height or action of the strings. This can be desirable from a player’s perspective. Figure 3 is a schematic illustration of such an arrangement, in which the bridge plate 12 is supported on a plurality of roller bearings 26. A gear arrangement (not shown) is provided to convert turning movement ofthe control arm 20 towards or away from the body 16 of the guitar to linear movement of the bridge plate 12. One example of a linear vibrato arrangement is described in US Patent No. 5,392,680.

One disadvantage of all of the above-described vibrato arrangements is that the acoustic coupling between the strings and the body of the instrument is relatively poor. This is a consequence ofthe relatively small mechanical contact area provided by the bearing or hinge arrangements between the bridge plate and the body. As a result, the tone of an instrument fitted with one of the known vibrato arrangements is often considered inferior to an equivalent instrument fitted with a fixed-bridge, nonvibrato arrangement, where the acoustic coupling between the strings and the body is substantially improved.

It would therefore be desirable to provide a vibrato assembly that reduces or mitigates at least some of the disadvantages of the prior art systems described above. In particular, it would be desirable to provide a vibrato assembly that does

-3not substantially change the height of the strings when in use, and that offers improved acoustic coupling compared to prior art systems. It is against this background that the present invention has been devised.

SUMMARY OF THE INVENTION

From a first aspect of the invention, a vibrato assembly for a stringed instrument comprising one or more strings under tension is provided. The vibrato assembly comprises a chassis for rigid attachment to a body of the instrument, a moveable bridge support to which one or more strings of the instrument are anchorable, and first and second spring plate elements for holding the bridge support substantially parallel to the chassis, the first spring plate element coupling a head part of the bridge support to a head part of the chassis and the second spring plate element coupling a tail part of the bridge support to a tail part of the chassis. The assembly further comprises at least one balancing spring for coupling the bridge support to the chassis to bias the bridge support against the tension of the strings in use, and an actuator lever coupled to the chassis and the bridge support and operable to displace the bridge support with respect to the chassis from a neutral position to change the pitch of the or each string.

With this configuration, the bridge support, spring plate elements and chassis together form a box-like structure in which movement of the bridge support with respect to the chassis is substantially linear, so that the height of the strings does not appreciably change when the assembly is operated and so that twisting or other undesirable movement of the bridge support is prevented. Furthermore, the box-like structure provides a solid and stable coupling between the strings and the body of the instrument without intervening hinges, bearings or other moving joints, thereby maximising acoustic transfer from the strings to the body.

In use, the actuator lever may be operated in a first direction to increase the string tension, by moving the bridge support in a tailward direction (i.e. away from the head and neck of the instrument). The actuator lever may be operated in a second

-4direction to decrease the string tension, by moving the bridge support in a headward direction (i.e. towards the head and neck of the instrument). Upon release of the actuator lever, the bridge support returns to a neutral position in which the forces acting on the bridge support due to the string tension, the or each balancing spring and the spring plate elements are balanced.

The first and second spring plate elements are preferably substantially parallel to one another when the bridge support is in the neutral position. The first and second spring plate elements preferably remain in a substantially parallel relationship during operation of the assembly, to hold the bridge support in a parallel position with respect to the chassis. Preferably, the first and second spring plate elements are substantially perpendicular to the bridge support and the chassis when the bridge support in the neutral position.

The first and second spring plate elements may extend across substantially the whole width of the chassis and the bridge support. In this way, the stability and acoustic transfer of the vibrato assembly can be maximised.

The chassis may comprise a chassis frame having a head chassis rail and a tail chassis rail disposed substantially parallel to the head chassis rail. The first and second spring plate elements may be attached to the head chassis rail and the tail chassis rail, respectively. Similarly, the bridge support may comprise a support frame having a head support rail and a tail support rail disposed substantially parallel to the head support rail, and the first and second spring plate elements may be attached to the head support rail and the tail support rail, respectively.

Preferably, the vibrato assembly comprises a spring carriage for coupling the or each balancing spring to the bridge support or the chassis and spring adjustment means for adjusting the position of the spring carriage to vary the load applied to the bridge support by the or each balancing spring. In this way, the vibrato assembly can be readily adjusted for optimum performance. For example, the position of the spring carriage can be adjusted so that the spring plate elements are substantially

-5parallel to one another and perpendicular to the chassis and the bridge support when the bridge support is in the neutral position.

The spring adjustment means may comprise a screw having a threaded part for engagement with a threaded bore of the spring carriage and a head part cooperable with the bridge support or the chassis. Guide means may be provided for guiding the spring carriage for linear movement with respect to the bridge support or the chassis. Preferably, the or each balancing spring is anchored to the chassis and coupled to the bridge support by the spring carriage.

The bridge support may comprise an actuator pin, and the actuator lever may be pivotably mounted on the actuator pin to couple the actuator lever to the bridge support. In one arrangement, a linkage is provided for coupling the actuator lever to the chassis. Preferably, a first end of the linkage is pivotably mounted to the actuator lever at a linkage pivot spaced from the actuator pin and a second end of the linkage is pivotably mounted to the chassis. The chassis may comprise an upstanding actuator mounting bracket, and the second end of the linkage may be pivotably mounted to the actuator mounting bracket. A detachable control arm may be provided for operating the actuator lever.

The vibrato assembly may include actuator adjustment means for adjusting the position of the linkage pivot with respect to the actuator pin, thereby to adjust the displacement of the bridge support with respect to the chassis for a given displacement of the actuator lever. Advantageously, with this arrangement, the “feel” of the vibrato assembly (i.e. the amount of resistance to operation) can be adjusted independently of the gauge of the strings used with the assembly.

It may be desirable to limit or selectively limit the range of movement of the bridge support in the headward and/or the tailward direction. To this end, the vibrato assembly may comprise a first tail stop surface associated with the bridge support and a second tail stop surface associated with the chassis, and the first and second tail stop surfaces may be cooperable to limit displacement of the bridge support in

-6a tailward direction with respect to the chassis. A switch arrangement may be provided for positioning the first and second tail stop surfaces to selectively allow or limit tailward displacement of the bridge support with respect to the chassis. For example, the switch arrangement may comprise a switch body mounted on the bridge support. Preferably, the switch body comprises the first tail stop surface and is moveable from a first position in which the first and second tail stop surfaces do not cooperate to a second position in which the first and second tail stop surfaces cooperate to limit displacement of the bridge support in the tailward direction. With this arrangement, the vibrato arrangement can be switched from an unlocked mode, in which both headward and tailward movement of the bridge support is possible, to a part-locked mode in which tailward movement of the bridge support is prevented or limited. This can be useful in preventing a change in tension in one string (for example due to string breakage or detuning) from affecting the tuning of the other strings.

The vibrato assembly may comprise a first head stop surface associated with the bridge support and a second head stop surface associated with the chassis. Preferably, the first and second head stop surfaces are cooperable to limit displacement of the bridge support in a headward direction with respect to the chassis. Where a switch arrangement as described above is provided, the switch body may further comprise the first head stop surface. In this case, when the switch body is in the first position or the second position, the first and second head stop surfaces preferably do not cooperate, and the switch body is preferably moveable to a third position in which the first and second tail stop surfaces and the first and second head stop surfaces respectively cooperate to limit displacement of the bridge support away from the neutral position. Thus, with this arrangement, the vibrato arrangement can be switched between unlocked, part-locked and fullylocked modes. In the fully-locked mode, the vibrato arrangement behaves as a fixed bridge of the instrument. A detent mechanism may be provided for releasably retaining the switch body in one or more of the operating positions.

The vibrato assembly can be used to support any suitable bridge arrangement for the instrument. For example, the vibrato assembly may further comprise a bridge plate for attachment to the bridge support, and the bridge plate may comprise anchor means for the or each string.

The present invention also extends, in a second aspect, to a musical instrument comprising a vibrato assembly according to the first aspect of the invention. The instrument may comprise a guitar, preferably an electric guitar.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1, 2 and 3, which have already been referred to above, are schematic drawings showing prior art vibrato assemblies.

Embodiments of the present invention will now be described, by way of example only, with reference to the remaining drawings, in which like reference signs are used for like features, and in which:

Figure 4 is a perspective view of a vibrato assembly according to an embodiment of the present invention;

Figure 5 is a side view of the vibrato assembly of Figure 1, fitted with a bridge plate;

Figure 6 is a perspective view showing a chassis, a bridge support and spring plate elements of the vibrato assembly of Figure 1;

Figure 7 is a perspective view of the vibrato assembly of Figure 1 when in use to decrease the string pitch;

Figure 8(a), (b) and (c) are side views of the vibrato assembly of Figure 1 when in use to decrease the string pitch, when in a neutral position, and when in use to increase the string pitch, respectively;

-8Figure 9 is a schematic side view of components of the vibrato assembly of Figure 1 when in use to decrease the string pitch;

Figure 10 is a cross-sectional view of a variant of the vibrato assembly of Figurel when in an unlocked configuration; and

Figures 11 (a) and 11 (b) are cross-sectional views of the vibrato assembly of Figure 10 when in part-locked and fully-locked configurations, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout this description, the terms “vertical”, “top”, “bottom” and similar terms are used to refer to the orientation of the assembly as shown in the accompanying drawings, although it will be appreciated that the assembly could be positioned in substantially any orientation in use. The terms “head”, “headward” and similar terms are used to refer to the side of the assembly that is closest to the head and neck of the instrument in use (i.e. towards the right hand side of Figure 5). The terms “tail”, “tailward” and similar terms are used to refer to the opposite side of the assembly that is furthest from the head and neck of the instrument in use (i.e. towards the left hand side of Figure 5).

Referring first to Figures 4, 5 and 6, a vibrato assembly 100 according to the invention comprises a chassis 102 that is mountable to the body of a guitar or other stringed instrument, a bridge support 104 that is positioned above and parallel to the chassis 102, and first and second flexure plates or spring plate elements 106, 108 that each extend substantially vertically between the chassis 102 and the bridge support 104.

The bridge support 104 comprises a generally rectangular frame structure having a front or head rail 112 and a parallel rear or tail rail 114. A pair of side rails 116, 118, shown most clearly in Figure 6, connect the head and tail rails 112, 114 of the bridge

-9support. Similarly, the chassis 102 also has a generally rectangular frame structure, with a head rail 122, tail rail 124 and side rails 126, 128, and an additional central rail 130 that bridges between the midpoints of the head and tail rails 122, 124. The side rails 126, 128 and central rail 130 are elevated with respect to the head and tail rails 122, 124 of the chassis 102, and the side rails 126, 128 are extended outwardly to provide mounting flanges 132 by which the chassis 102 can be screwed or otherwise attached to the body of the instrument.

The first spring plate element 106 is attached along a bottom edge portion to the head side of the chassis head rail 122, and along a top edge portion to the head side of the bridge support head rail 112. The second spring plate element 108, which can be seen most clearly in Figure 6, is similarly attached along bottom and top edge portions to the rear or tail sides of the chassis tail rail 124 and the bridge support tail rail 114. The spring plate elements 106, 108 are held in place using suitable machine screws 134. In this way, the spring plate elements 106, 108, the chassis 102 and the bridge support 104 together form a box-like structure.

Referring to Figure 5, a bridge plate 136 is mounted to the bridge support 104, by way of screws (not shown) that engage with threaded mounted holes 138 in the bridge support 104 (see Figures 5 and 6). The bridge plate 136 may be of any suitable type. As will be familiar to those skilled in the art, the bridge plate 136 preferably includes one or more tail pieces 138 to which each string (not shown) of the instrument can be anchored and one or more saddles 140, disposed on the head side of the or each tail piece 138, upon which the strings are supported. The saddles 140 are preferably adjustable so that the intonation and action of the strings can be modified as appropriate. In the illustrated example, the tail pieces 138 are fitted with fine-tuners 142 to provide for adjustment of the string tension. For clarity, the bridge plate 136 is shown only in Figure 5 and is omitted from Figures 4 and 6 to 11.

When strings are fitted to the bridge plate 136, the tension of the strings tends to pull the bridge plate 136, and therefore the bridge support 104, in the headward direction (i.e. towards the head and neck of the instrument, and towards the right in

-10Figures 4 to 9). To counterbalance this force, a plurality of balancing springs 144, shown only in Figure 4, are provided.

Referring to Figure 4, the balancing springs 144 are in the form of compression springs with looped end terminations, and extend generally diagonally from the tail rail 124 of the chassis 102 towards the head side of the bridge support 104. The lower end of each spring 144 is retained by a hook formation 146 disposed on the tail rail 124 of the chassis 102. The upper end of each spring 144 is retained by a spring carriage 148 in the form of a bar that extends laterally between the side rails 116, 118 of the bridge support 104. The spring carnage 148 includes upwardlyextending posts 150 to which the end terminations of the springs 144 can be hooked. In the illustrated example, two balancing springs 144 are fitted, but hook formations 146 and posts 150 are provided to enable a further two balancing springs to be fitted if required. More generally, any suitable number of balancing springs could be used.

An adjustment mechanism is provide to allow the distance between the spring carriage 148 and the head rail 122 of the bridge support 104 to be adjusted. To this end, the spring carriage 148 includes a threaded bore that accepts a correspondingly threaded part of an adjustment screw 152. The adjustment screw 152 extends between the head and tail rails 112, 114 of the bridge support 104. A plain end part of the adjustment screw 152 is mounted in a plain bore 154 formed in the tail rail 114, and a thrust washer 156 of the adjustment screw 152 bears on the head side of the tail rail 114. The spring carnage 148 is guided for linear movement within the frame structure of the bridge support 104 by tracks 158 disposed on the inside surfaces of the side rails 116, 118.

The plain end (not visible) of the adjustment screw 152 is accessible from the tail side of the assembly 100 and is configured to engage with a hex key or other suitable tool. Rotation of the adjustment screw 152 causes the spring carriage 148 to move towards or away from the head rail 112 of the bridge support 104. In this way, the counterbalancing force applied to the bridge support 104 by the balancing springs 144 can be adjusted to compensate for the tension of the strings, for

-11 example when changing the gauge of the strings.

With suitable selection and adjustment of the balancing springs 144, the assembly 100 can be arranged so that the spring plate elements 106, 108 are substantially relaxed and parallel to one another when the assembly 100 is in a neutral position, as shown in Figures 4 to 6. For clarity, the balancing springs 144, spring carriage 148 and adjustment screw 152 are shown only in Figure 4, and are omitted from Figures 5 to 11.

Referring again to Figure 4, the vibrato assembly includes an actuator mechanism 160 for causing displacement of the bridge support 104 in the headward and tailward directions with respect to the chassis 102. The actuator mechanism 160 comprises an actuator block or lever 162 that is pivotably mounted to the bridge support 104 by an actuator pin 164. The actuator pin 164 is mounted to and extends laterally outward from an upstanding tab 166 on one of the side rails 118 of the bridge support 104, so that the actuator lever 162 can pivot about the actuator pin 164. A detachable control arm 168 is releasably attached to the actuator lever 162 by way of a threaded coupling 170.

A linkage arm 172 is provided to couple the actuator lever 162 to the chassis 102. A first end of the linkage arm 172 is pivotably mounted to the actuator lever 162 at a linkage pivot 174 that is spaced from the actuator pin 164. A second end of the linkage arm 172 is pivotably mounted to a linkage pin 176 that is retained by an upstanding actuator bracket 178. The actuator bracket 178, in turn, is attached to one of the side rails 128 of the chassis 102 so that the actuator bracket 178 effectively forms part of the chassis 102.

The linkage pivot 174 takes the form of an adjustable knuckle joint having a pivot block 180 that is mounted in a recess 182 of the actuator lever 162. The pivot block 180 is in threaded engagement with a vertical adjustment screw 184 that extends across the recess 182 and is retained by engagement with bores in the actuator lever 162 on the top and bottom sides of the recess 182. The first end of the linkage

-12arm is forked to receive the pivot block 180 therebetween, and each fork includes a circular hole to accept a respective pin 186 of the pivot block 180.

With this arrangement, movement of the control arm 168 causes the actuator lever 162 to turn about the actuator pin 164. As can be seen in Figures 7 and 8(a), pressing the control arm 168 towards the body of the instrument causes clockwise movement of the actuator lever 162 (in the illustrated orientation). Because the actuator lever 162 is coupled to the chassis 102 by the linkage arm 172, the actuator lever 162 pulls the actuator pin 164, and hence the bridge support 104, in a headward direction with respect to the chassis 102. This moves the bridge plate 136 (shown only in Figure 5) towards the head end of the instrument, reducing the tension in the strings to lower their pitch.

As can be best seen in Figure 9, which shows the bridge support 104, the chassis 102 and the attached spring plate elements 106, 108 only (with the other components omitted for clarity), the spring plate elements 106, 108 bend to accommodate the headward movement of the bridge support 104, whilst ensuring that the bridge support 104 remains parallel to the chassis 102. As can also be seen in Figure 9, the head and tail rails 122, 124 of the chassis 102 and the head and tail rails 112, 114 of the bridge support 104 are suitably chamfered so that the rails 112, 114, 122, 124 do not foul the bending movement of the spring plate elements 106, 108.

Referring back to Figure 8, releasing the control arm 168 allows the assembly 100 to return to the neutral position, as shown in Figure 8(b), to restore the string tension and pitch to the normal tuning. The bridge support 104 is biased to return to the neutral position by the combination of the string tension and the balancing springs 144 (not shown in Figure 8), as well as the resilience of the spring plate 106, 108 elements to return to their vertical, unbent configurations.

Pulling the control arm 168 away from the body of the instrument, as shown in Figure

8(c), causes anticlockwise movement of the actuator lever 162, which moves the

-13bridge support 104 and the bridge plate in a tailward direction to increase the tension in the strings to raise their pitch. Again, releasing the control arm 168 causes the assembly 100 to return to the neutral position of Figure 8(b), restoring the normal tuning of the instrument.

Because the spring plate elements 106, 108 are constrained along their top and bottom edges, where they are mounted to the bridge support 104 and the chassis 102 respectively, the available bending modes ofthe spring plate elements 106,108 are restricted. In turn, this limits the freedom of movement ofthe bridge support 104 with respect to the chassis 102. In particular, the spring plate elements 106, 108 can bend to allow substantially linear displacement of the bridge support 104 in a headward and tailward direction with respect to the chassis 102, resulting in a decrease or an increase in the string tension, respectively. However, sideways linear movement and twisting movement of the bridge support 104 with respect to the chassis 102 is substantially prevented. Thus the box-like structure of the assembly 100 provides an inherently strong and stable mounting for the bridge plate that is able to flex freely in the desired directions only. Furthermore, the spring plate elements 106, 108 are solidly connected to both the bridge support 104 and the chassis 102, allowing substantially improved acoustic transfer from the strings to the body of the instrument compared with prior art arrangements in which bearings, hinges, pivots or other moveable joints are used to allow the desired movement.

It will be appreciated that movement of the bridge support 104 in the headward and tailward directions will be accompanied by a small component of movement in the vertical direction, with the bridge support 104 moving slightly towards the chassis 102. The amount of vertical movement is however very small in comparison to the vertical deflection of the strings of the rocking fulcrum arrangements of the prior art and is unlikely to be noticed by the player. Thus the movement ofthe bridge support 104 in the assembly 100 of the present invention can be described as substantially linear.

The spring plate elements 106, 108 are formed from a suitable spring material, such

-14as spring steel, so that each spring plate element 106, 108 can bend to accommodate the full extent of movement of the bridge support 104 and return to the neutral position under fully elastic deformation. The spring plate elements 106, 108 are matched, with substantially identical thicknesses, dimensions, and material properties, so that the bridge support 104 remains substantially parallel to the chassis 102 at all times in use.

In the illustrated embodiment, the amount of force that must be applied to the control arm 168 to achieve a given displacement of the bridge support 104 can be adjusted to alter the level of resistance or “feel” of the vibrato assembly 100, without the need to change the gauge of the strings or alter the balancing springs 144.

Referring again to Figures 4 and 7, the top of the adjustment screw 184 is accessible from the top side of the assembly 100 and is arranged to receive a suitable tool, such as a hex key, so that the adjustment screw 184 can be turned. Rotation of the adjustment screw 184 causes the pivot block 180 of the linkage pivot 174 to move upwards or downwards in the recess 182 of the actuator lever 162, thus changing the mechanical advantage of the actuator mechanism 160. Moving the linkage pivot 174 upwards decreases the distance between the actuator pin 164 and the linkage pivot 174, so that less force need be applied to the control arm 168 to move the actuator lever 162 through a given angle (with a corresponding reduction in the displacement of the bridge support 104). Moving the linkage pivot 174 downwards in the recess 182 increases the distance between the actuator pin 164 and the linkage pivot 174, increasing the force required to move the control arm 168 and the actuator lever 162 through a given angle (with a corresponding increase in the displacement of the bridge support 104). This gives the player the choice of optimising the assembly 100 for, for example, rapid vibrato with relatively small pitch deviation using light force on the control arm 168, or for large pitch dives or increases using heavy force on the control arm 168.

Figures 10 and 11 show a variant of the vibrato assembly 100a that includes a multiposition selector switch arrangement 200 that provides further control over the

-15available modes of movement of the bridge support 104 with respect to the chassis 102. In particular, in this example, the switch arrangement 200 allows the player to select between permitting both headward and tailward movement of the bridge support 104, allowing only headward movement of the bridge support 104, or preventing both headward and tailward movement of the bridge support 104 to lock the bridge support 104 in a fixed position with respect to the chassis 102.

Referring first to Figure 10, the switch arrangement 200 comprises a switch body 202 that is pivotably mounted on the actuator pin 164. The switch body 202 is disposed between two extended arms 204, 206 of the actuator bracket 178. An upper surface 208 of the switch body 202 is shaped as a rocker switch that is accessible from the top of the vibrato assembly 100a. The switch body 202 is provided with two part-cylindrical stop surfaces 210, 212 that are selectively positionable to engage with or abut corresponding stop surfaces 214, 216 on the arms 204, 206 of the actuator bracket 178.

In particular, the switch body 202 includes a first tail stop surface 210 that is disposed towards the tail side of the assembly 100a, and the actuator bracket arm 204 on the tail side of the switch body 202 provides a second tail stop surface 214. The switch body 202 also includes a head stop surface 212 disposed towards the head side, and the actuator bracket arm 206 on the head side of the switch body 202 provides a second head stop surface 216.

A detent mechanism 218 is provided to locate the switch body 202 in one of three angular orientations around the actuator pin 164, corresponding to three locking modes of the vibrato assembly 100a. The detent mechanism 218 comprises a spring-loaded plunger 220 that is mounted vertically in a threaded bore formed in one of the side rails 118 of the bridge support 204. The plunger 220 is arranged to engage with one of three angularly-spaced grooves 222 formed in a part-cylindrical guide surface of the switch body 202. In this way, the switch body 202 is held in one of the three positions by the detent mechanism 218, and movement of the switch body 202 to one of the other positions requires sufficient pressure to be applied to

-16overcome the holding force ofthe detent mechanism 218. This prevents accidental switching ofthe switch mechanism 200 and provides positive tactile feedback to the user when switching between locking modes.

With the switch body 202 in a first orientation, as shown in Figure 10, the first tail stop surface 210 is angularly positioned so that it does not come into contact with the second tail stop surface 214. Thus movement of the bridge support 104 in the tailward direction (to the right in Figure 10) remains possible. Similarly, the first head stop surface 212 is angularly positioned so that it does not come into contact with the second head stop surface 216, and movement ofthe bridge support 104 in the headward direction (to the left in Figure 10) also remains possible. Accordingly, with the switch body 202 in the first position, the vibrato assembly 100a is unlocked for free movement in either direction.

If the switch body 202 is moved to a second orientation, as shown in Figure 11(a), the first tail stop surface 210 comes into abutment with the second tail stop surface 214, but the first head stop surface 212 is still positioned clear of the second head stop surface 216. Thus, with the switch body 202 in this second position, the vibrato assembly 100a is in a part-locked configuration. Movement of the bridge support 104 in the tailward direction is blocked by the cooperation between the first and second tail stop surfaces 210, 214, but movement of the bridge support 104 in the headward direction is still possible. The vibrato assembly 100a may be switched to the part-locked mode in order to avoid loss of tuning due to a string breaking or when strings are de-tuned for playing in alternate tunings, whilst maintaining the ability to use the vibrato assembly 100a for downward pitch adjustments.

In a third orientation of the switch body 202, shown in Figure 11 (b), the first tail stop surface 208 is positioned to abut the second tail stop surface 214 and the first head stop surface 212 is positioned to abut the second head stop surface 216. Now, movement of the bridge support 104 in either direction is blocked, so that the vibrato assembly 100a is in a fully-locked mode, in which it acts like a fixed bridge with no vibrato function. This mode can be useful when vibrato is not required, or when

-17movement of the bridge is otherwise undesirable (such as when performing unison bends).

It will be appreciated that, instead of a three-way switch arrangement, a two-way switch arrangement could be provided, for example to provide only the unlocked and fully-locked modes. It is also possible that the vibrato assembly could be permanently configured in the part-locked mode, in which case the switch body could be omitted and the first tail stop surface could be part of or rigidly attached to the bridge support. By suitable positioning of the stop surfaces, a further or alternative mode is also possible, in which tailward movement of the bridge support is possible but headward movement of the bridge support is prevented. In this case, a four-way switch could be provided, or this mode could take the place of one of the other modes.

Further modifications and variations of the vibrato assembly are also possible.

For example, an actuator adjustment mechanism need not be provided, and instead the actuator lever could be connected to the linkage arm at a fixed distance from the actuator pivot. More generally, any suitable actuator means for controlling the displacement of the bridge support with respect to the chassis could be provided.

In the illustrated examples, the spring plate elements are planar when in their relaxed configurations. However, the spring plate elements could have an alternative form when relaxed, such as a shallow “S” or “Z” shape. Similarly, the spring plate elements need not extend vertically when the vibrato assembly is in the neutral position, but instead the spring plate elements could be inclined so that the cross sectional shape formed by the bridge support, chassis and spring plate elements is rhomboidal.

The balancing springs need not be mounted on an adjustable carriage, but could instead be stretched between fixed mounting points provided on the chassis and the bridge support. In another arrangement, the balancing springs are mounted to fixed

-18points on the bridge support, and are coupled to the chassis by way of an adjustable carriage.

It will be understood that, although most likely to be used in an electric guitar, the vibrato assembly of the present invention is not limited to use in any particular stringed instrument. For example, the assembly could conceivably be used in an acoustic guitar, bass guitar, lap steel guitar or any other stringed instrument. The assembly could be provided as a kit for retrospective fitting to an existing instrument having a fixed bridge or vibrato assembly, or for use in the manufacture of a new instrument. The assembly could also be more substantially integrated into an instrument. For example, the chassis of the assembly could be attached to or formed integrally with a chassis of the instrument.

The adjustment mechanisms described above that allow adjustment of the force applied by the balancing springs and the mechanical advantage of the actuator mechanism could, with suitable modification, be applied alone or in combination to substantially any vibrato assembly, including those types of vibrato assembly known from the prior art. Similarly, the switch arrangement for selectively locking operation of the vibrato assembly in one or both directions could also be applied to other types of vibrato assembly.

Further modifications and variations not explicitly described above are also possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. A vibrato assembly for a stringed instrument comprising one or more strings under tension, the vibrato assembly comprising:

a chassis for rigid attachment to a body of the instrument;

a moveable bridge support to which one or more strings of the instrument are anchorable;

first and second spring plate elements for holding the bridge support substantially parallel to the chassis, the first spring plate element coupling a head part of the bridge support to a head part of the chassis and the second spring plate element coupling a tail part of the bridge support to a tail part of the chassis;

at least one balancing spring for coupling the bridge support to the chassis to bias the bridge support against the tension of the strings in use; and an actuator lever coupled to the chassis and the bridge support and operable to displace the bridge support with respect to the chassis from a neutral position to change the pitch of the or each string.

2. A vibrato assembly according to Claim 1, wherein the first and second spring plate elements are substantially parallel to one another when the bridge support is in the neutral position.

3. A vibrato assembly according to Claim 1 or Claim 2, wherein the first and second spring plate elements extend across substantially the whole width of the chassis and the bridge support.

4. A vibrato assembly according to any preceding claim, wherein the chassis comprises a chassis frame having a head chassis rail and a tail chassis rail disposed substantially parallel to the head chassis rail, and wherein the first and second spring plate elements are attached to the head chassis rail and the tail chassis rail, respectively.

5. A vibrato assembly according to any preceding claim, wherein the bridge support comprises a support frame having a head support rail and a tail support rail disposed substantially parallel to the head support rail, and wherein the first and second spring plate elements are attached to the head support rail and the tail support rail, respectively.

6. A vibrato assembly according to any preceding claim, comprising a spring carriage for coupling the or each balancing spring to the bridge support or the chassis and spring adjustment means for adjusting the position of the spring carriage to vary the load applied to the bridge support by the or each balancing spring.

7. A vibrato assembly according to Claim 6, wherein the spring adjustment means comprises a screw having a threaded part for engagement with a threaded bore of the spring carriage and a head part cooperable with the bridge support or the chassis.

8. A vibrato assembly according to Claim 6 or Claim 7, comprising guide means for guiding the spring carriage for linear movement with respect to the bridge support or the chassis.

9. A vibrato assembly according to any preceding claim, wherein the bridge support comprises an actuator pin, and wherein the actuator lever is pivotably mounted on the actuator pin to couple the actuator lever to the bridge support.

10. A vibrato assembly according to Claim 9, comprising a linkage for coupling the actuator lever to the chassis, wherein a first end of the linkage is pivobtably mounted to the actuator lever at a linkage pivot spaced from the actuator pin and a second end of the linkage is pivotably mounted to the chassis.

11. A vibrato assembly according to Claim 10, comprising actuator adjustment means for adjusting the position of the linkage pivot with respect to the actuator pin thereby to adjust the displacement of the bridge support with respect to the chassis for a given displacement of the actuator lever.

12. A vibrato assembly according to any preceding claim, comprising a first tail stop surface associated with the bridge support and a second tail stop surface associated with the chassis, wherein the first and second tail stop surfaces are cooperable to limit displacement of the bridge support in a tailward direction with respect to the chassis.

13. A vibrato assembly according to Claim 12, comprising a switch arrangement for positioning the first and second tail stop surfaces to selectively allow or limit tailward displacement of the bridge support with respect to the chassis.

14. A vibrato assembly according to Claim 13, wherein the switch arrangement comprises a switch body mounted on the bridge support, wherein the switch body comprises the first tail stop surface and is moveable from a first position in which the first and second tail stop surfaces do not cooperate to a second position in which the first and second tail stop surfaces cooperate to limit displacement of the bridge support in the tailward direction.

15. A vibrato assembly according to any preceding claim, comprising a first head stop surface associated with the bridge support and a second head stop surface associated with the chassis, wherein the first and second head stop surfaces are cooperable to limit displacement of the bridge support in a headward direction with respect to the chassis.

16. A vibrato assembly according to Claim 15 when dependent on Claim 14, wherein the switch body further comprises the first head stop surface, wherein, when the switch body is in the first position or the second position,

-22 the first and second head stop surfaces do not cooperate, and wherein the switch body is moveable to a third position in which the first and second tail stop surfaces and the first and second head stop surfaces respectively cooperate to limit displacement of the bridge support away from the neutral 5 position.

17. A vibrato assembly according to any preceding claim, further comprising a bridge plate for attachment to the bridge support, wherein the bridge plate comprises anchor means for the or each string.

18. A musical instrument comprising a vibrato assembly according to any preceding claim.

Intellectual

Property

Office

Application No: GB1708463.3